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Aphelocoma coerulescens once included scrub jays in California and Mexico as well, with the different populations identified as subspecies. Recently, this species has been revised so that A. coerulescens only includes Florida scrub jay populations. Other scrub jays are now A. californica, western scrub jays, and A. ultramarina, Mexican jays or gray-breasted jays. Island scrub jays, A. insularis, occur on Santa Cruz Island, off the coast of California. Taxonomic revisions were based on genetic and behavioral evidence. An example of behavioral evidence is that only Florida scrub jays use a cooperative breeding strategy.
Florida scrub jays communicate using visual cues such as head bobbing; a movement used during territorial encounters. The complexity of their cooperation in defense, breeding, and hunting also suggests that intra-nest communication is important. They use vocalizations to exchange information and warn predators, such as the hiccup sound produced by female birds. Another example of this is the warning calls that these birds use to alert each other to the presence of predators.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Overall numbers of A. coerulescens are declining mainly due to habitat loss, even though most of its remaining habitat is public land. In an effort to stop this habitat destruction, land is being set aside to be left in a natural state where fires clear the area and create a scrub habitat. Some land is being allocated to be burned at regular intervals, and only portions will be burned at a time. Also, to avoid satellite systems, where groups of birds are geographically isolated from the larger group, corridor connections are being made in Florida Scrub-Jay habitat.
US Migratory Bird Act: protected
US Federal List: threatened
IUCN Red List of Threatened Species: vulnerable
There are no known adverse effects of A. coerulescens on humans
These birds are well-loved by bird watchers. They have beautiful bright blue colors and are active and vocal. They are important subjects for research on the evolution of cooperation.
Positive Impacts: ecotourism ; research and education
Florida scrub jays play a role in maintaining population levels of insects and small vertebrates on which they feed. They also act as seed dispersers of scrub oaks (Quercus species) by caching acorns. This species is also known to eat ticks from the backs of large mammals such as white-tailed deer (Odocoileus virginianus).
Ecosystem Impact: disperses seeds
Mutualist Species:
These birds generally forage near the ground. They search for food by hopping along the ground. Acorns are the most important part of the diet, which they bury and cache for later use. Other nuts and fruits are also eaten. Florida scrub jays also eat insects, such as grasshoppers (Orthoptera) and butterflies and moths (Lepidoptera), bird eggs, and small vertebrates such as frogs, snakes, lizards, and mice. Some of these are Hyla cinerea, H. squirella, Anolis carolinenis, A. sagrei, Cnemidophorus sexlineatus, Coluber constrictor, Tantilla relicta relicta, Opheodrys aestivus, Mus musculus, Peromyscus gossypinus, P. polionotus, and Podomys floridanus. Foods offered by humans are also eaten as a supplement.
Animal Foods: mammals; amphibians; reptiles; eggs; insects; terrestrial non-insect arthropods
Plant Foods: seeds, grains, and nuts; fruit
Foraging Behavior: stores or caches food
Primary Diet: omnivore
Florida scrub jays, Aphelocoma coerulescens, occur from the Florida panhandle through central Florida. Florida scrub jays previously occupied most of the counties of peninsular Florida, they are currently found from Flagler, Marion, and Citrus counties in the north to Collier, Glades, and Palm Beach counties in the south.
Biogeographic Regions: nearctic (Native )
Aphelocoma coerulescens is a habitat specialist, living mainly in scrub woodlands of peninsular Florida. These birds prefer thickets of sand pine and scrub oak, recently burned sites, and shore-dune thickets, all habitats found on the sandy soils of this area. Aphelocoma coerulescens is found in scrub habitats along coasts, rivers, and on some high inland ridges. They will not generally nest in heavily forested areas. Dominant tree species in Florida scrub jay habitat are sand live oak (Quercus virginiana), Chapman oak (Quercus chapmanii), myrtle oak (Quercus myrtifolia), and scrub oak (Quercus inopina). Florida scrub jays may also be found in suburban areas.
Range elevation: 0 to 200 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: scrub forest
Other Habitat Features: suburban ; riparian
Average lifespan is 4.5 years, but Florida scrub jays are known to live for up to 11 years in the wild.
Range lifespan
Status: wild: 15.8 (high) years.
Average lifespan
Status: wild: 4.5 years.
Average lifespan
Status: wild: 179 months.
Aphelocoma coerulescens is usually between 25 and 30 cm long and weighs about 77 grams. The plumage of adult males and females looks alike, but males are slightly larger than females. The head, nape, wings, and tail are pale blue. The back and belly are pale gray. The throat and chest are white and bordered by a blue gray bib. Juveniles differ in appearance from adults in that they have dull or dark brown upperparts. Florida scrub jays look similar to other jays (Cyanocitta), but do not have a crest, white-tipped wings or tail feathers, or black barring. Molting occurs between June and November, and is at its highest between July and September. During late summer and early fall juveniles cannot be distinguished from adults.
Average mass: 77 g.
Range length: 25 to 30 cm.
Average wingspan: 43 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Average mass: 78.7 g.
Florida scrub jays defend themselves against predators by using lookouts to give warnings to other birds. They are social, alert, and aggressive and will actively mob predators. Scrub jays may be preyed on by predatory birds, such as hawks and falcons, or by domestic cats and bobcats.
Known Predators:
Florida scrub jays mate for life. This species uses a technique called cooperative breeding, where extended families live together but have only one breeding pair. Courtship of a breeding pair is drawn out, with males using vocalizations and posturing to attract females. Average nesting groups consist of three birds, but can range from two to eight. Helper birds are usually the young of the original breeding pair. Copulation is discreet and not visible to other jays. Helper jays help the breeding pair by defending the territory and providing food for young. Helper birds are reproductively capable, and evidence suggests that they delay breeding because they are unlikely to be successful in reproducing. When helpers do go on to become breeders in a new nest, males generally inherit their natal territory when the breeding male dies. Females emigrate from their natal area. If the mate of a breeding adult dies, that adult may take on helper roles and relinquish their role as a breeder.
Mating System: monogamous ; cooperative breeder
Nesting occurs from early March to late June. Florida scrub jays breed for the first time between the ages of 1 and 7 years, with most individuals breeding for the first time between 2 and 4 years of age. The eggs of are pea green to pale glaucous green and spotted with irregularly shaped markings. Helper male birds have lower testosterone levels than breeding males.
Breeding interval: Florida scrub jays produce one clutch per season.
Breeding season: Breeding occurs from early March through late June.
Range eggs per season: 1 to 5.
Average eggs per season: 3-4.
Average time to hatching: 17-18 days.
Range fledging age: 16 to 21 days.
Average time to independence: 10 weeks.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; oviparous
Average time to hatching: 17 days.
Average eggs per season: 4.
Average age at sexual or reproductive maturity (male)
Sex: male: 365 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 365 days.
Fledglings depend on adults for food for about 10 weeks. Only the breeding pair builds the nest; which is about 18 to 20 cm in outer diameter, and 9 to 10 cm inner diameter. Nests are usually 1 to 2 meters from the ground. Only the breeding female incubates the eggs. Feeding of fledglings is done by both the breeding pair and helper birds. Helper birds do not incubate eggs or brood nestlings. Florida scrub jays use a lookout technique to watch for predators where one bird is chosen as the lookout and watches for oncoming attacks from a high position. Breeders and helpers will help chase away egg predators, which can be other species or other Florida scrub jays.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Protecting: Male, Female); post-independence association with parents; inherits maternal/paternal territory
Florida scrub-jays occur in scrub communities of peninsular Florida with low tree cover and high cover of low-growing evergreen oak shrubs such as sand live oak (Quercus geminata), Chapman oak (Q. chapmanii), and myrtle oak (Q. myrtifolia). Scrub communities include oak scrub [5,32,146] and scrubby flatwoods [5,143,146]. Flatwoods have shrub and ground layers similar to those of oak scrub, but also include an overstory of slash (Pinus elliottii) or longleaf pine (P. palustris) [14]. The term scrubby flatwoods may also be used for areas that are mixtures of flatwoods and oak scrub [22]. Florida scrub-jays also use coastal strand in areas where it borders oak scrub. Coastal strand is a shrubby community comprised of species such as twinberry (Myrcianthes fragrans), Hercules-club (Zanthoxylum clava-herculis), and redbay (Persea borbonia) [16]. Florida scrub-jays also use slash pine-turkey oak (Quercus laevis) at Archbold Biological Station [143], oak-saw-palmetto (Quercus spp.-Serenoa repens) and saw-palmetto-oak at Kennedy Space Center [32], and sand pine (P. clausa) scrub on the Ocala National Forest [46]. Florida scrub-jays are occasionally observed in adjacent communities such as swale marshes [20].
Oaks are a critical feature of high-quality Florida scrub-jay habitat. Florida scrub-jays at Archbold Biological Station and nearby areas use oaks for nesting more than would be expected based on their availability [134,143]. Saw palmetto was used less than expected based on availability at Archbold Biological Station [143]. At Placid Lakes and Archbold Biological Station, over 80% of nests occurred in oaks [13]. At Archbold Biological Station, 48% of nests were in sand live oak, 19% in sandhill oak (Q. inopina), 16% in myrtle oak, and 5% in Chapman oak [146]. At Kennedy Space Center, Florida scrub-jays nested in open oak scrub communities more than expected based on availability, but they also selected oak-saw-palmetto communities [27]. Nest success in this area was highest in territories with at least 50% oak cover [37]. Regenerating pasture adjacent to oak scrub at Archbold Biological Station had nest success and yearling production similar to that of the oak-dominated community [49].
Florida scrub-jays forage [146] and roost [80] primarily in oak scrub, but they also forage in palmetto patches [146], grassy road margins [96,146], and regenerating pasture [49,96]. At Archbold Biological Station, an index of nutritional status of young was significantly (P<0.02) greater in territories that had greater proportion of oak cover [70]. Throughout the year, Florida scrub-jays at Archbold Biological Station roost in communities dominated by sandhill oak, sand live oak, and a mixture of oaks more frequently than in saw-palmetto, staggerbush (Lyonia spp), and saw-palmetto-staggerbush communities [80].
Territories with less than about 1 acre (0.4 ha) of open oak scrub often do not provide high-quality habitat [27,32,35]. At the Kennedy Space Center, recruitment typically exceeded mortality in patches of open oak scrub greater than 66 feet wide (20 m) and comprised of scrub more than 3 feet (1 m) tall. In areas of scrub less than 66 feet (20 m) wide, recruitment was less than mortality [27]. At the Tel-4 site, oak scrub ridges less than 1 acre that occurred more than 525 feet (160 m) from larger oak scrub ridges were generally population sinks [32]. In 3 Florida scrub-jay metapopulations along the coast in Brevard County, areas with less than 1 acre of oak scrub had lower reproductive success than those with more oak scrub or areas intersecting well-drained scrub [35].
Oak-dominated communities seem to provide higher quality habitat for Florida scrub-jays than those codominated by saw palmetto [27,32]. For instance, at Kennedy Space Center, nest success was lower in oak-saw-palmetto communities than open oak scrub [27]. Several demographic measures were significantly (P<0.035) greater in oak-dominated territories that overlapped well-drained, oak ridges compared to territories on poorly-drained soils dominated by saw-palmetto and overlapping less than 1 acre (0.4 ha) of oak scrub (saw-palmetto-oak) (Table 1). Mortality exceeded recruitment in saw-palmetto-oak territories [32]. For details of reproductive success in oak scrub see Reproductive output.
Table 1. Average Florida scrub-jay demographic performance in oak and saw-palmetto oak communities [32] Demographic variable Oak ridges Saw-palmetto-oak Average number of Florida scrub-jays per family group (P=0.034) 3.11 2.44 Breeder survival (P=0.012) 83% 68% First-year nonbreeder survival (P=0.001) 90% 31% Demographic performance* (P=0.013) 0.22 -0.38 *(yearlings produced−breeder deaths) ÷ territories in a given plant community type;See the Fire Regime Table for a list of plant communities in which Florida scrub-jay may occur and information on the FIRE REGIMES associated with those communities.
Because density is not a reliable indicator of Florida scrub-jay habitat quality [14] or demographic success [26], this review includes few publications that use Florida scrub-jay density as an indicator of population health, demographic success, or similar variables. For instance, Florida scrub-jays may occur at high densities in tall, dense scrub [18] despite Florida scrub-jay mortality rates exceeding reproduction in these communities [26] (see Scrub height). At Kennedy Space Center, habitat suitability models were more strongly correlated with indicators of demographic success, including breeder survival and fledgling production, than they were to Florida scrub-jay density [26,54].
Most of the information on life history and diet presented below was obtained from reviews, including a comprehensive review from Birds of North American written in 1996 [146].
Breeding: Florida scrub-jays form monogamous pairs [24,146] typically when 2 or 3 years old, although this ranges from 1 to 7 years old [146]. Divorce rates were less than 1% at Kennedy Space Center [24] and 6% at Archbold Biological Station [146]. Following the death of a mate, 87% of Florida scrub-jays at Happy Creek remained breeders on their territory, and 8% bred on a neighboring territory. A small proportion of Florida scrub-jays do not breed the year following loss of a mate [24,146]. Based on over 20 years of data from Archbold Biological Station, breeding Florida scrub-jays average 4.2 breeding seasons [146].
Florida scrub-jays typically raise 1 brood a year [143,146]. They will lay replacement clutches after unsuccessful nesting attempts. At Archbold Biological Station, clutches of 3 or 4 eggs were most common, with a range of 1 to 6 eggs [146]. True second broods are rare [143,146].
Novice breeders at Archbold Biological Station bred later and had smaller clutches than experienced breeders [143]. However, a later analysis found pair bond duration had a stronger influence on Florida scrub-jay clutch initiation date (and in turn clutch size [104,119,120]) than breeder age or breeder experience [10].
Available discussions of breeding behaviors include information on pair formation [138], mating displays, nest construction, nestling care, sentinel and mobbing behavior, time budgets [144,146], helper behaviors, and territorial interactions [138,144,146].
Cooperative breeding: Florida scrub-jays are cooperative breeders with up to 6 nonbreeding helpers assisting the breeding pair with territory defense, predator mobbing, and sentinel activity. In many instances, they also help feed nestlings and fledglings. Several studies have shown helpers increase reproductive success of breeders [20,28,66,67,98]. At Archbold Biological Station, helpers were also associated with greater breeder survival [144]. Data from Kennedy Space Center suggest that the benefit helpers provide may be negated in poor quality habitat, such as dense vegetation and forest edges (See Preferred Habitat). In these areas effectiveness of visual detection and mobbing of predators may be reduced and some predators that avoid detection, such as nocturnal snakes, may be more common (see Tree cover) [37]. Because Florida scrub-jay sentinel behavior is more effective when there are Florida scrub-jays in adjacent areas [24,27], small populations supported by low-quality habitat may be less effective at detecting predators [24].
Helpers range in age from 1 to 7 years old, but are frequently yearlings that help in their natal territory [146]. At Happy Creek, most Florida scrub-jays delayed breeding for 1 to 2 years. The male to female sex ratio of nonbreeders was 3:1, with 1-year-old females breeding more frequently (P=0.025) than 1-year-old males [24]. Models based on data collected from 1997 to 2005 in 20 Florida scrub-jay populations along central Florida's Atlantic coast showed that yearlings and males delayed breeding more frequently than older nonbreeders and females. The probability of remaining a helper decreased by nearly half when age changed from juvenile to adult and other variables were unchanged. Delayed breeding was lowest at intermediate Florida scrub-jay densities. The authors suggest that ability to find a mate likely limits breeding opportunities at low densities, and competition for territories likely limits breeding opportunities at high densities [34]. During the period of delayed breeding, helpers foray into neighboring territories to detect and fill breeding vacancies [126].
Florida scrub-jay survival is higher, breeder turnover lower, and delayed breeding more common in high-quality habitat [29]. Mortality of breeders leads to breeding vacancies which allow Florida scrub-jays to breed earlier than would otherwise be the case [21,28,34]. At Happy Creek, an area of low-quality habitat and declining populations, breeding yearling females were 10 times more common than at Archbold Biological Station, an area of high-quality habitat [24] and relatively stable populations. At the Tel-4 site, territories in comparatively poor palmetto-oak habitat had lower survival and a greater proportion of yearling breeders than territories in higher quality habitat [32].
More detailed descriptions of Florida scrub-jay social interactions, including mobbing behavior [65], dominance hierarchies, territory defense, time budgets, and communication, including use of certain vocalizations in specific contexts [144,146], are available.
Florida scrub-jays primarily eat arthropods and acorns [50,146]. Arthropods taken from leaves or leaf litter [61] are most common in the summer diet [50]. Young in wildland areas are only fed arthropods, particularly Lepidoptera and Orthoptera. Florida scrub-jays have been observed foraging on the backs of ungulates, presumably eating ticks [146]. A foraging study at Archbold Biological Station performed from January 1974 to May 1975 found that fresh acorns are eaten from August to December and cached primarily from September to November. Cached acorns are eaten throughout the year, most commonly from September through February. Each Florida scrub-jay cached from 6,500 to 8,000 acorns [50]. Florida scrub-jays cache acorns on sand or vegetation, such as moss and palmetto fronds [146]. Florida scrub-jays at Archbold Biological Station were more likely to recache acorns stored in bare sand or sites with low soil moisture compared to those in more mesic microenvironments. Florida scrub-jays often cache out of view of conspecifics [83]. Fitzpatrick [61] suggests that Florida scrub-jay habitat selection is driven by the birds' reliance on acorns and sandy areas for caching them. Small vertebrates such as frogs, lizards, and small snakes comprise the majority of vertebrate prey. Other small vertebrates, berries, seeds, carrion, and snails are rarely eaten [146].
Low-quality food available to suburban Florida scrub-jays may contribute to poor condition and low survival of young in these areas, although other factors may be involved (See Reproduction in suburban areas). Individuals from Archbold Biological Station and Placid Lakes that obtained food the fastest bred the earliest, suggesting that food availability, and not necessarily food quality, provides a cue to begin breeding [62]. There is limited evidence that the predictability of food availability in the suburbs may also influence initiation of breeding [119]. Despite greater foraging rates, adult Florida scrub-jays at Placid Lakes had lower net energy gain compared to individuals at Archbold Biological Station [62]. The lower abundance of high-quality invertebrate food in the suburbs, the relative ease of obtaining human-provided food, the lack of a difference between food delivery rates in suburban and wildland areas [107,122], and greater brood reduction in areas and years with low food abundance [122] suggest that Florida scrub-jays in suburbs provide nestlings a detrimental amount of low-quality food.
Experimental supplementation with high-quality food at Archbold Biological Station may improve fledging success and survival to independence, particularly in difficult years [103,120]. Earlier laying in supplemented territories led to larger clutch sizes [104,119,120]. Based on these findings Schoech and others [120] suggest that supplemental feeding could be a useful management option to quickly increase effective carrying capacity or assist in translocation efforts, although they caution that it could also lead to predator entrainment and increased disease transmission.
Little information is available on the direct impacts of fire on Florida scrub-jays. Florida scrub-jays are unlikely to suffer direct mortality from fire. It is generally accepted that large, fast-moving fires may result in mortality, but adult birds typically have the mobility to avoid fire [39,51,90]. Despite negative short-term impacts, only the smallest Florida scrub-jay populations are at risk of extirpation from severe wildland fires [17].
Limited evidence suggests that in most years, fire has little impact on nest success. From 1969 to 1978, 3 Florida scrub jay eggs and 1 nestling were killed by fire at Archbold Biological Station. For both eggs and nestlings, fire mortality represented less than 1% of losses. Descriptions of the study area suggest that portions were periodically burned under prescription while other areas were not burned during this period [144]. Because wildfires in Florida are most common in the summer (see FIRE REGIMES), it is likely that most Florida scrub-jays will fledge before the fire season starts. Fledgling Florida scrub-jays may still be weak fliers in early June and may therefore be more vulnerable to early summer fires (see Timing of breeding, nesting, and early development). Literature reviews [90,105] have used fire characteristics and life history of species to speculate on possible effects of fire on nest success and bird populations. Based on these generalizations, Florida scrub-jays' selection of shrubby vegetation for nest sites suggest that fires during the breeding season could result in considerable egg, nestling, and/or fledgling mortality. Renesting following failed nesting attempts (see Breeding) may mitigate the direct effects of early spring fire on Florida scrub-jay recruitment. However, because Florida scrub-jays typically rear only 1 brood per year, fires in the mid- to late-breeding season (April to June) may impact recruitment [90,105].
Typically, Florida scrub-jays only abandon territories following large and uniformly severe fires [95,138,146]. Without patches of unburned scrub, extensively burned territories do not provide the acorns, nesting cover, or escape cover required by Florida scrub-jays [17,95]. Territories with as little as 10% to 25% of unburned scrub may still be used by Florida scrub-jays (Faulhaber 2012 personal communication [57]). Florida scrub-jays at Happy Creek remained on territories following restoration treatments of overgrown, fire-resistant areas on the site; restoration treatments included mechanical treatment from August 1992 to January 1993 and prescribed burning in Feburary 1993. All breeders made at least one nesting attempt within a few months of the prescribed fire [114]. In contrast, after prescribed burning from 1988 to 2000 at Happy Creek, Florida scrub-jays shifted their territories from severely burned areas to areas where tall scrub remained. Prescribed fires burned 40% to 60% of the study area every 3 to 5 years and did not burn entire territories in any year [24]. Recolonization by Florida scrub-jays following habitat restoration is most likely in cases where Florida scrub-jays occur in adjacent areas and the population is increasing and/or the habitat quality of the adjacent area is declining (see Population management).
The Florida scrub-jay is endemic to Florida [127,139]. It occurs in a few large and several small populations, many of which are isolated to varying degrees [126]. Florida scrub-jay historically occurred in 39 of 40 counties of peninsular Florida [146]. By 1983, it was extirpated from several counties, including Broward, Dade, Duval, Pinellas, and St. Johns counties [46]. As of 1993, the Florida scrub-jay was extirpated from Alachua and Clay counties, and 6 counties had less than 10 breeding pairs each [146]. See Population trends for a discussion of Florida scrub-jay population decline.
Florida scrub-jays have been studied for long periods at Archbold Biological Station in central Florida and the Kennedy Space Center/Merritt Island National Wildlife Refuge on the east-central Florida coast. The Archbold Biological Station occupies 5,190 acres (2,100 ha) that overlap a portion of the Lake Wales Ridge metapopulation of Florida scrub-jays, in which about 565 territories where documented in 1992-1993 [126]. The initial study of Florida scrub-jays at Archbold Biological Station began in 1969 [49,146] on a site about 860 to 990 acres (350-400 ha) in size [144]. Starting in the late 1990s, several studies compared individuals at Archbold Biological Station with individuals in suburban areas located about 6 miles (10 km) north, in Placid Lakes, Florida (hereafter, Placid Lakes) [12,13,107,134]. Studies of Florida scrub-jays at the Kennedy Space Center/ Merritt Island National Wildlife Refuge (hereafter Kennedy Space Center) began in the 1980s [24,28]. There are 2 sites within Kennedy Space Center where much of this research occurred. Near the southern boundary of the Kennedy Space Center is a 590-acre (240 ha) [32] scrubby flatwoods site designated Tel-4 or T4 (Tel-4 is used in this review) [28,32]. The Happy Creek site is an 990-acre (400 ha) [24] scrub community about 8 miles (12 km) north of Tel-4 from which fire was excluded for about 20 years before prescribed burning began in 1979 [24]. Because of its overgrown character it provided relatively poor habitat for Florida scrub-jays into the early 2000s [16,24]. A 1992-1993 survey documented 536 Florida scrub-jay territories at Kennedy Space Center [126]. Schmalzer and others [113] provide a detailed characterization of scrub communities at the Kennedy Space Center and other areas within Brevard County.
The effects of fire on Florida scrub-jays depend on many factors including site characteristics, time since fire (see Postfire succession and habitat quality), characteristics of the fire (see Influence of fire characteristics on Florida scrub-jay response), and dynamics of the Florida scrub-jay populations that are affected. Although Florida scrub-jays will use recently burned areas (see Florida scrub-jay use of burned areas), fire commonly results in a short-term decrease in habitat suitability or availability. When fires are severe and extensive they may increase extinction probability of small and isolated Florida scrub-jay populations (Breininger unpublished data cited in [29]). In the long-term, however, fire can improve Florida scrub-jay habitat quality by increasing openings and reducing tree densities and shrub height (see Postfire succession and habitat quality). Fires that burn in a mosaic at the local scale or that kill many tall shrubs and trees may immediately benefit Florida scrub-jay habitat quality [17]. Areas that are not burned at least every 20 years do not support healthy Florida scrub-jay populations (see Influence of fire on Florida scrub-jay demographics), and fire exclusion leads to changes in vegetation that render scrub unsuitable for Florida scrub-jays (see Postfire succession and habitat quality).
Prioritizing treatment: A substantial amount of burning is required to maintain oak scrub and adjacent native vegetation. At Kennedy Space Center, 202 prescribed fires averaging 460 acres each were performed from 1993 to 2002, for a total of 93,402 acres burned in fire-maintained habitats [5]. In the early 2000s a Fire Strike Team was established to assist land managers in carrying out burns throughout the Florida scrub-jay's range. In its 4th year, 11 organizations had submitted requests for assistance in burning 34 conservation areas, and the team had assisted in burning 140 fire management units in 13 conservation areas [73]. See Threats for information on the prevalence of overgrown scrub as of the mid-1990s and Habitat management for discussion of topics not directly related to fire such as reserve design considerations and the importance of acquisition and maintenance of high-quality Florida scrub-jay habitat.
Given the amount of vegetation requiring restoration, prioritizing areas for treatment has been recommended. Breininger [22] states that achieving optimal habitat conditions in every territory is "unreasonable", implying that it is more realistic to seek a balance of optimal and suboptimal habitat that allows for Florida scrub-jay population growth. Scrub management guidelines for peninsular Florida recommend providing optimal habitat in 70% of potential territories and keeping most of the remainder shorter than optimal [81]. Restoration of overgrown habitat is difficult and may produce less benefit than maintenance of existing Florida scrub-jay habitat (see Restoration of overgrown scrub). Focusing on maintaining optimal areas and restoring areas that are slightly overgrown is likely to maximize benefits [106]. However, restoration of overgrown scrub to increase carrying capacity of conservation areas and/or available habitat for Florida scrub-jays in small populations is citical for long-term recovery (Faulhaber 2012 personal communication [57]). Generalized fire management recommendations, such as performing most fires in summer [17] or burning several small areas [46], may not be practical given the large amount of area that needs treatment. Breininger and others [17] suggest burning year-round until the amount of scrub needing treatment is reduced.
Characteristics of the surrounding landscape may help to prioritize treatments. Locating treatments near areas occupied by Florida scrub-jay increases the likelihood of success ([35], Faulhaber 2012 personal communication [57]). Small restoration treatments in areas within landscapes comprised primarily of good-quality Florida scrub-jay habitat are likely more beneficial for Florida scrub-jays than similar efforts in areas dominated by dense overgrown scrub or forests [114]. Alternative reserve designs that categorize vegetation based on habitat suitability, potential habitat suitability (with and without mechanical treatment), distance to human development, and the economics of restoration and fire management would assist in efficient allocation of available resources [16].
An adaptive management program that incorporates vegetation structural characteristics [30] and Florida scrub-jay and other specialist species' population status [24,128] into decision-making is likely needed to successfully restore scrub communities and provide for stable Florida scrub-jay populations [16,22]. This would require monitoring [22,37,128] and incorporation of these factors into reporting [30]. A technique using remote sensing to track fire occurrence is described by Shao and Duncan [121]. An adaptive management system could also increase knowledge about topics that are not well understood, such as the role of openings in Florida scrub-jay demography [37].
Recommendations for fire characteristics: Spatial arrangement of burned areas on the landscape influences treatment effectiveness. At Kennedy Space Center, recommendations included placing treatments so that oak scrub that is occupied by Florida scrub-jays does not border forests [17]. In Brevard County, oak scrub that is burned frequently to maintain openings may be best located adjacent to mesic flatwood vegetation [17]. Vegetation adjacent to scrub requires maintenance fires [17] for many of the same reasons as scrub (e.g., preventing fuel accumulation [16,17,111]) and also because frequently burned matrix vegetation generally increases the habitat value of the adjacent scrub for Florida scrub-jays [17,35] (see Landscape features). Matrix vegetation typically burns more frequently than oak scrub. For instance, at the Kennedy Space Center, mesic flatwoods are burned within the recommended frequency of every 1 to 8 years [25], and these fires are occationally used to ignite neighboring oak scrub [22] (see FIRE REGIMES).
The need for open areas and optimal height scrub may be met by performing patchy burns [17,61,110,116,146]. Performing patchy burns on variable rotations based on habitat characteristics [94], such as vegetation height, may allow for habitat maintenance over the large areas required. Repeated patchy fires result in some areas burning more frequently than others [32]; frequently burned sites provide open areas, while those that burn less often provide oak cover needed for nesting and cover [46,61]. Mosaic burns are appropriate in cases meeting the following criteria: the Florida scrub-jay population is small and isolated, there is no Florida scrub-jay habitat adjacent to the burn area, there are resources to burn again within a year, there are resources for spatially explicit mechanical cutting to contain severe fire to localized areas, and/or the vegetation is a mixture of tall and optimal habitat and the Florida scrub-jay population is stable and near capacity. In cases where interspersion of the tall scrub is low, it may be possible to burn only the tall patches [22]. Burning late in the growing-season, when rains assist in keeping fires small, may result in a mosaic of recently burned and various-aged scrub [52]. Burning several small patches within a given area on a rotation, such as 10% every year on a 10-year rotation, could achieve the desired outcome, although this would require burning every year or two which may be impractical [46]. Similarly, performing small burns (<500 acres (200 ha)) every year while avoiding burning any area in consecutive years has been recommended for experimental areas. These experimental burns on small areas may speed restoration, and results could inform future Habitat management decisions [16].
It has been recommended that the size of burned patches be smaller than Florida scrub-jay territories. In areas with clusters of Florida scrub-jay territories, Breininger and others [32] recommend leaving at least 2.5 acres (1 ha) of optimal-height scrub in every territory. Other recommendations include creating a mosaic with 60% of the scrub unburned [16] and burning no more than 25% of a refuge occupied by Florida scrub-jays in a single fire [61]. Florida scrub-jays may remain on recently burned territories if at least 10% to 25% of the scrub remains unburned (Faulhaber 2012 personal communication [57]). Burning entire territories likely has the least impact on large populations and in areas where adjacent areas can provide Florida scrub-jay habitat. This strategy is generally not recommended in areas occupied by small Florida scrub-jay populations [81]. Restoration that focuses on the territory-scale is important, since that is the landscape unit related to demography [24].
Recommended fire frequency in oak scrub ranges from about 5 to 20 years [16,17,29,146], including 10 to 20 years at Archbold Biological Station [61] and Brevard County [106]. Fire frequency for specific areas should be based on plant community height, structure, and composition; management history; and site characteristics. For example, at Kennedy Space Center burning is recommended before scrub taller than 5.5 feet (1.7 m) accumulates, because it provides low-quality Florida scrub-jay habitat and becomes increasingly difficult to burn [32]. In scrub with less than 5% bare ground at Archbold Biological Station, burning was recommended when scrub reached 3.3 to 5 feet (1.0-1.5 m) tall. In areas with more open space, shrubs may be allowed to reach greater heights before burning [46]. More frequent burning may be required to restore overgrown areas (see Restoration of overgrown scrub). Several researchers have suggested basing fire frequency on site characteristics that influence the growth rate of oaks and other Florida scrub-jay habitat characteristics [17,19,46]. For instance, more rapid growth along the Atlantic Coastal Ridge compared to interior Florida scrub-jay habitat may result in a shorter fire-return interval being optimal in costal scrub communities [17,110]. Given the importance of the state of the vegetation in influencing management decisions, a monitoring program is essential.
Limited evidence suggests growing season fires may have greater benefits for Florida scrub-jay habitat than fall or winter fires. However, year-round burning may be required in areas with large acreages needing treatment [17]. At Archbold Biological Station the majority of burning is performed in summer to mimic the natural fire regime, and winter fires are mainly performed in overgrown vegetation [91]. At Kennedy Space Center from 1984 to 2004, the greatest number of acres, on average, was burned in November [52]. The consequences of prescribed burning in fall and winter are not well understood. Differences in scrub vegetation response following winter and summer prescribed burns at Kennedy Space Center were slight and suggest season does not have a significant effect on the postfire response of scrub vegetation [63]. Reductions in postfire sprouting of hardwoods [114] and cover of oaks (reviewed by [17]) are greater following growing season fires than following winter fires. The effect this has on openings is unclear; some research suggests growing season fires result in persistent openings [52]. Prescribed fire on a site in central Kennedy Space Center in November did not result in persistent openings [18]. Fall fires may cause greater pine mortality than fires in other seasons (Menges and Deyrup in preparation cited in [91]).
Variability in prescribed burning has been recommended for shrublands [42] including Florida scrub [16,81,91,93,94,113]. At Archbold Biological Station, spatial and temporal heterogeneity are incorporated into fire management by burning units of various sizes at fire-return intervals ranging from 6 to 9 years in scrubby flatwoods to 15 to 59 years in rosemary (Ceratiola ericoides) scrub [91]. Mosaics of varying stand ages of sand pine are recommended on the Ocala National Forest [67]. A mosaic of variable fire-return intervals also benefits scrub species other than Florida scrub-jay [94]. Management that is identical in all stands of the same community results in homogenization that does not allow for preservation of natural variability or species diversity [102]. In areas where it is feasible, management should attempt to mimic the full range of variability in the natural fire regime [93], including season, with most fires occurring in summer [16,81]. Extensive fires may be used in some situations, such as when scrub has been degraded by fire exclusion and either the site is not occupied by Florida scrub-jays or the population is large and widespread (see Restoration of overgrown scrub).
Optimal burning conditions for scrub are narrow, with a small window between conditions where oak scrub will not burn and those where fire is impossible to control [95]. A description of prescription conditions and associated behavior of prescribed fires performed on 2 sites at Kennedy Space Center is available. Flame lengths on these 2 sites ranged from 2.0 to 16.4 feet (0.6-5 m), rates of spread from 20 to 400 m/hr, and extent ranged from 60% to over 90% of the areas being burned. Fuel distribution and weather differences account for most of the differences between the fires [114]. The small window for burning may be an obstacle to use of fire for habitat improvement. For instance, during the first 2 years of the Fire Strike Team's operation, only 18 prescribed fires were performed due to drought conditions [74]. Custer and Thorsen [48] describe the prescribed fire conditions for a successful 30-acre stand-replacement fire in sand pine-scrub on the Ocala National Forest.
Restoration of overgrown vegetation: Fire exclusion may result in changes that cannot be treated with prescribed fire alone (see Impacts of fire exclusion). Based on data from aerial imagery from Kennedy Space Center, the probability of tall vegetation transitioning to short vegetation or optimal vegetation after prescribed fire was zero, and the odds of mixed optimal and tall vegetation transitioning to short or optimal after prescribed fire were less than 4.5% [78] (see Table 4). After about 20 years of fire exclusion at Happy Creek [24], scrub became fire resistant and species of hardwood hammock forests began to establish [53]. Prescribed burning at Happy Creek did not restore desired scrub characteristics that were present before fire exclusion [26]. Repeated winter fires did not restore openings in areas of fire-excluded oak scrub at Kennedy Space Center [114]. Prescribed fire reversed some but not all of the trends associated with fire exclusion at Kennedy Space Center. For instance, pine stands on disturbed areas of Tel-4 and hardwood swamps at Happy Creek persisted, and openings were not restored in oak scrub at Happy Creek [53].
Severe [16,29] large fires about every 20 years may restore overgrown scrub vegetation. These fires consume fuels [29] and can burn areas that are resistant to fire under typical prescription conditions [24]. Current status of the habitat and Florida scrub-jay population are important factors to include when considering this option [29], since small or fragmented populations are unlikely to recover from extensive fires (See Influence of fire characteristics on Florida scrub-jay response). Long-term negative impacts are unlikely following uniformly severe fire that burns a few territories of a large population, while that is probably not the case in small populations (Faulhaber 2012 personal communication [57]). A description of ignition techniques and prescriptions for large, severe fires is available [16]. Such fires may be useful when the area adjacent to the large burn is Florida scrub-jay habitat, there are few resources available to treat the area mechanically, the area of tall scrub is extensive, frequent burning is impractical, and/or severe fire is need to create open, sandy areas [22]. In tall areas that are still occupied by Florida scrub-jays, it may be possible to burn after clearing vegetation around the best remaining habitat patches. These unburned areas should not be near roads, forests, or areas with dense trees or tall shrubs [22]. Firebreaks may be needed for fire control [16,52,61], but they could result in simple edges that would increase the risk of predation on Florida scrub-jays [16,17,52,114].
Overgrown scrub is typically restored by mechanical treatments followed by prescribed fire [30,106,113]. Preliminary results suggest these treatments may restore overgrown scrub [109,114,137] and create openings that persist longer than those created by burn-only treatments [15,111] (see below). At the Kennedy Space Center habitat quality was not expected to improve without mechanical cutting [30]. In areas where overgrown vegetation is next to human development, mechanical techniques may be the only method available for opening scrub habitat [146]. Equipment and techniques used for mechanical treatment in scrubby vegetation at Kennedy Space Center are described by Schmalzer and others [111,114].
Mechanical treatment followed by burning is generally effective in creating persistent openings in oak scrub. Burning slash piles at Kennedy Space Center [15,111] and mowing followed by burning 1 year later near Placid Lakes [137] resulted in more persistent openings than fire alone. At Kennedy Space Center, area of openings declined by about half 7 years after burning slash piles, while openings in fire-only treatments were nearly gone within a few years. The researchers suggest that the heat produced by burning slash kills roots and rhizomes of sprouting species, requiring colonization of other vegetation to close the opening [111]. Use of caution in applying this method has been recommended because repeated burning required in oak scrub requires fuel continuity [111]. At a site near Placid Lakes, bare sand cover was significantly (P<0.001) greater after mowing followed by burning 1 year later, than in mow-only, burn-only, and control treatments. On a site without the year delay, cover of open sand in mow-and-burn areas did not differ significantly from that in burn-only treatments, but both had greater cover of bare sand than mow-only and control treatments [137]. Using repeated fire on a 2- to 4-year return interval over 15 years may also create openings when shrubs are killed by reduction of carbohydrate reserves [16,116]. Because it may take up to 4 years for enough fuel accumulation to carry a fire and repeated fires are needed, this method takes longer than mechanical treatment. In communities with a substantial pine component, burning downed logs and snags may create openings, although this may produce smoke issues [16].
Scrub recovery time after mechanical treatment can be rapid. Vigorous recovery after mechanical treatment has been reported [93,109], with height growth in cut-and-burn treatments exceeding that in burn-only treatments by 50% or more in some cases [111]. Sand pines may also recover faster after cut-and-burn than burn-only treatments [46]. However, oak cover was similar in cut-and-burn and burn-only plots 4 years following treatment at Happy Creek [112], and both mow-and-burn and burn-only treatments near Placid Lakes reduced cover and height of woody vegetation relative to controls 5 years after treatment [137]. Saw-palmetto cover is often reduced to a greater extent and for a longer duration after mechanical treatment than after burning alone [15,111]. This may be especially relevant to flatwoods, where saw-palmetto increases in dominance with fire exclusion and is typically not top-killed when fire is reintroduced [30]. Since saw-palmetto can be important in providing fuel to allow for burning following mechanical treatment, large reductions of saw-palmetto can interfere with Florida scrub-jay Habitat management [111]. Breininger and others [17] note that treatments that reduce pine canopy such as salvage logging with minimal soil disturbance are likely to improve Florida scrub-jay habitat quality.
Reported impacts of mechanical treatments on Florida scrub-jays have been positive or neutral. At 2 sites at Kennedy Space Center, no Florida scrub-jays abandoned their territories during mechanical treatment followed by prescribed fires [114]. On the Ocala National Forest, regenerating sand pine adjacent to occupied Florida scrub-jay habitat is typically colonized by Florida scrub-jays when oaks on the regenerating site are about 3 feet (1 m) tall [46]. Although the number of Florida scrub-jay pairs was greater in burned treatments of Cape Canaveral Air Force Station, the number of fledglings was greatest in cut treatments (Stevens and Knight 2004 cited in [128]). An oak-palmetto scrub site at Kennedy Space Center that was mechanically cleared developed into oak scrub that was densely occupied by Florida scrub-jays 20 years later [18]. Spatially arranging treatments to prevent treating too much area within territories [114] and performing treatments outside the breeding season [7] are strategies for minimizing direct detrimental effects of mechanical treatments on Florida scrub-jays. Mechanical treatments can have negative impacts on other species, including gopher tortoises. Mitigation of these impacts should be incorporated into treatment plans [81].
Mechanical treatments should be used with caution for several reasons. Mechanical restoration is expensive [30,40], costing an estimated $3,390 to $19,310 more per hectare than maintenance fires as of 2001 [40]. Mechanical treatments have the potential to cause soil damage [16,17,46,93], which may impact fuels [16,17] and increase establishment and spread nonnative invasive plants [17,93]. If these treatments are performed over areas as large as Florida scrub-jay territories they would result in too much short vegetation, which could impact Florida scrub-jay demography [78]. Mechanical treatments may lead to proliferation of vines that require spot control, may result in simple edges that could increase predation risk [114], have uncertain long-term impacts [61,93], and raise other concerns regarding replacing fire with mechanical treatments in fire-adapted systems [93].
Because of the disadvantages of mechanical treatments and the advantages of using fire, mechanical treatments are recommended as preparation for maintenance fires [40,81,93,112,114,137]. According to a review of studies using mechanical treatment in scrub, the positive effects of a mechanical treatments may be lost if it is not followed by repeated prescribed fires, because of vigorous sprouting by many species [93]. Burning within 3 months of mechanical treatment has been recommended, since flammability begins to decline within about 6 months of treatment [81]. Relatively short fire-return intervals may be needed following mechanical treatment in long unburned scrub until the vegetation is fully restored [111,113]. Because of this, it is important that mechanical treatment does not reduce the potential for frequent burning, such as causing excessive loss of saw-palmetto [111]. For information on fires used to maintain scrub vegetation, see Recommendations for fire characteristics.
Lightning-caused fires in Florida generally occur during the summer rainy season [1,52,145] and are most common in July [52]. At Archbold Biological Station there is an average of 2.1 lightning fires per year [1]. A study of the fire regime at Kennedy Space Center determined that lightning-caused fires were generally small, likely because they occur during the summer rainy season [52]. From 1984 to 2004, under the Kennedy Space Center's managed fire regime, winter was the season with most acres burned, and November was the month with the most acres burned [52].
Oak scrub is a fire-maintained community [5] and can burn as frequently as every 5 to 10 years ([5], Myers 1990, Archbold Biological Station unpublished data cited in [146]), although historic fire-return intervals may have been as long as 30 to 70 years in some areas [1]. As of 2009, the mean fire-return interval for a 73,000-acre (29,540 ha) area at Kennedy Space Center and surrounding federal lands was 14.4 years [52], although portions of this area have fire-return intervals of 3 to 5 years [30]. Oak scrub fires are typically severe [5,95,113] and stand-replacing [5]. Rapid spread rates and flame lengths of 40 to 50 feet (12-15 m) are typical in oak scrub at Kennedy Space Center [5]. There is usually insufficient fuel in oak scrub to burn within 5 years of the previous fire, and on xeric sites fuel accumulation is slower [95]. Oak leaves accumulate in the litter layer but do not substantially contribute to fueling fires [1]. For information on biomass in oak-saw-palmetto communities of Kennedy Space Center see Schmalzer and Hinkle [117].
Other communities occupied by Florida scrub-jay burn regularly, but at widely differing frequencies. Scrubby flatwoods at Kennedy Space Center with "natural" fuel loadings experience moderate severity fires every 3 to 7 years, with the shrubby understory consumed. The pine overstory only burns in extreme weather conditions [5]. Fire-return intervals in coastal scrub and coastal strand are typically more than 10 years [87]. In sand pine communities, fires historically occurred every 30 to 60 years [41]. Sand pines are killed when the fires crown, but their seeds are released from serotinous cones [36]. The Fire Regime Table summarizes characteristics of FIRE REGIMES for vegetation communities in which Florida scrub-jays may occur. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Oak scrub communities are less flammable and burn less frequently than many other native plant communities such as sandhills [136], swale marshes [25], and flatwoods [5,25,52]. Oak scrub is difficult to ignite [5]. For instance, an oak-saw-palmetto scrub community at Kennedy Space Center could not be ignited aerially during a wet winter, and fires were patchy under other conditions [116]. It is common for fires to stop at the edge of oak scrub habitats [36,136]. Factors that contribute to this comparative lack of flammability in oak scrub include evergreen leaves, lack of fine fuels such as grasses and forbs, and slow litter accumulation [136]. At Kennedy Space Center, oak scrub burned less frequently than mesic flatwoods and swale marshes [25]. Mesic flatwoods and swale marshes are comprised of vegetation such as saw-palmetto and grasses that are more flammable, and fuel accumulates more quickly in these communities than in oak scrub vegetation [1,2,3,101,115,118]. When oak scrub communities iginite, it is often due to fire spreading from adjacent, comparatively flammable communities [5,52]. This ignition source is an important factor influencing the frequency of fire in oak scrub [16,95].
Fires in oak scrub are generally patchy [87,95], with burned patches usually smaller than Florida scrub-jay territories [146]. The patchiness of fire is influenced by weather conditions and scrub type, with xeric scrubs experiencing more heterogeneous fires [95]. Fires in scrub at Archbold Biological Station are more patchy than stand-replacement fires in sand pine scrub on the Ocala National Forest, because fire-return intervals are longer and more fuel accumulates between fires in sand pine scrub [46]. In an area at Kennedy Space Center including oak scrub that was burned under prescription 3 times and burned in a wildfire once in 20 years, only 30% of the area was burned 3 or 4 times. The patchiness of fire in scrub communities contributes to the mosaic of openings and mixed-age oak cover that provide high-quality Florida scrub-jay habitat. The patchily burned scrub had areas not burned in more than 10 years that provided oak cover and areas that had burned more frequently that provided open sandy areas [25]. Patchiness of fire influences recovery of scrub vegetation, partly because some plant species colonize burned areas from unburned patches [95].
Although the management fire regime and the natural fire regime have similar fire-return intervals at Kennedy Space Center, the size distributions differ. The natural fire regime is characterized by many frequent small fires and a few large fires, which are up to 4 times the size of prescribed fires. Medium-sized wildfires are most often suppressed, since they are big enough to detect and generate concern but small enough to effectively control. The management fire regime is less variable, with more medium-sized fires [52].
Habitat fragmentation due to land conversion has resulted in reduced fire frequency in Florida scrub-jay habitats. This is due to the reduction in flammable neighboring habitats (see above), succession to fire resistant communities resulting from fire exclusion (see below), and directly through conversion to land uses that impede fire spread, such as roads [1,30], or require fire exclusion, such as suburban development [1,146]. At Kennedy Space Center, edges made vegetation transitions to taller states more likely and transitions to shorter states less likely, because edges reduced both fire spread and fire frequency [30]. In Brevard County, disrupted FIRE REGIMES caused by fragmentation reduced habitat quality, contributed to Florida scrub-jay population decline, and magnified the impacts of direct habitat loss [35]. Even minimal land conversion can fragment vegetation sufficiently to disrupt fire spread. For instance, modeling simulations predicted a 50% reduction in fire extent with as little as 10% anthropogenic landcover [56].
Detrimental impacts of fire exclusion in scrub vegetation of Florida include persistent increases in tree height and density [5,72] that contribute to increased fire resistance [110,114], reduced flammability [5,24,32], and decreased fire frequency and heterogeneity. This may increase the potential for severe fire [5,46,113], due to increased amounts [5] and continuous distribution [114] of fuels. However, prolonged fire exclusion can result in a conversion to fire resistant vegetation; for example, scrub communities may succeed to xeric hammock vegetation [113,114] and marshes to forest [30,53]. Once vegetation becomes fire resistant, restoration using prescribed fire is difficult and/or ineffective [15,24,29,30,108,114], at least under typical burning conditions [24,111]. In these cases, restoration commonly requires mechanical treatments combined with repeated prescribed fire [17] (see Restoration of overgrown scrub). For information on the impacts of fire exclusion on Florida scrub-jay habitat quality, see Postfire succession and habitat quality.
Considerable research has been conducted on the relationships between fire, Florida scrub-jays, and their habitat, but readers should be aware of its limitations. Some studies on Florida scrub-jays have the same limitations as those addressing bird response to fire in southwestern ponderosa pine (Pinus ponderosa) forests, such as being restricted in spatial or temporal scale, having small sample sizes, or including confounding factors [58]. Some use Florida scrub-jay density to compare sites, which has its own limitations (see Biological Data). Although several studies compare Florida scrub-jay demography between habitats with varying characteristics (see Preferred Habitat), many focus on shrub height and do not include information on the fire or other treatments that initiated scrub development. Few studies describe the history of the site, such as how often a site has been burned in recent years. Also, several of the studies at Archbold Biological Station [49,143,144,145,146] and surrounding areas (e.g. [49,134]; [12,13]; and [12,134]), Tel-4 [16,26,28,30,32], Happy Creek [16,24,26,28,30], and along the Atlantic Coast of central Florida [17,29,34,35] apparently have overlapping datasets.
Although the negative impacts of fire exclusion on Florida scrub-jay and their habitat are well-documented, data supporting specific management alternatives are relatively scarce [133]. Recommendations to avoid homogeneous and fixed burning regimes (see Fire Management Considerations) and too frequent fire (see Postfire succession and habitat quality) are common [81,94]. Patchy fires that recur at variable intervals based on habitat conditions and site characteristics are likely to maintain high-quality Florida scrub-jay habitat, while scrub that has not burned in about 20 years or more becomes overgrown, difficult to burn (See FIRE REGIMES), and poor habitat. In these cases, high-severity fire or mechanical treatments followed by relatively frequent fire may be needed until the scrub is successfully restored (see Restoration of overgrown scrub).
Florida scrub-jay use of burned areas: Several studies have shown that Florida scrub-jays establish in scrub communities treated with prescribed burning or combinations of mechanical removal and prescribed burning. Although a 1-year study at Kennedy Space Center found no difference in Florida scrub-jay density between burned and unburned sites [33], the use of density, a short timeframe, and small survey stations limit inference. Florida scrub-jays were absent from overgrown scrub in Blue Springs State Park in 1989 when the first clearcut and burn treatment was implemented [133]. As of 2011, 10 Florida scrub-jay families occurred there (Faulhaber 2012 personal communication [57]). Similar results have been observed following similar treatments and maintenance burning in scrub communities in Oscar Scherer State Park in Sarasota County, Lyonia Preserve in Volusia County, and Halpata Tastanaki Preserve in Marion County [133]. At Kennedy Space Center, Florida scrub-jays used treated areas for foraging, caching acorns, and nesting within 18 months of prescribed burning [16]. At the Savannas Preserve State Park along the Atlantic Coast, a Florida scrub-jay established a territory within about a year of a "trial" burn in an area that had been overgrown [123].
At Kennedy Space Center, density of Florida scrub-jays in areas burned by a wildfire (13.2 birds/40 acre) and in areas burned by prescribed fire (9.91 birds/40 ha) did not differ significantly. Areas were at a similar stage of postfire succession [68].
Existing territories may shift following fire. At Kennedy Space Center, most territories were not "optimal" after cutting and burning treatments. Because much of the vegetation was initially too short to provide high-quality habitat, Florida scrub-jays fought to obtain remaining unburned tall patches [24].
Influence of fire on Florida scrub-jay demographics: Although populations often decline just after fire (see Postfire succession and habitat quality), especially after uniformly severe fire covering extensive areas (see Influence of fire characteristics on Florida scrub-jay response), Florida scrub-jays in areas that are regularly burned typically have good demographic performance. In periodically burned areas of Archbold Biological Station, lifetime reproductive success was 1.1 to 1.3 yearlings, while in unburned areas it was only 0.4 to 0.6 yearlings [59,145]. Pairs in unburned habitat produced an average of 1.6 fledglings and 0.3 yearling per year, and pairs in periodically burned habitat produced 2 fledglings and 0.76 yearlings per year [144,145]. Breeder survival was also lower in unburned than burned habitat [145] (see Table 2). At Archbold Biological Station, fledgling production was greater in burned than unburned habitat in 14 of 18 years, and survival was greater in burned than in unburned habitat in 14 of 15 years [61]. Statistical significance of these differences was not tested. Causes of the reduced success in overgrown habitat have not been identified. Arthropod abundance in June and July was similar in burned and unburned habitat at Archbold Biological Station, so that is not a likely explanation. Other possible explanations include reduced abundance of arthropods in unburned habitat at other times of year, vegetation structure and/or composition that led to increased difficulty detecting or capturing prey (see Structural features), decreased acorn production [47], lack of bare ground to cache acorns, and increased vulnerability to predators [47,146].
Preliminary data following the reintroduction of fire to Kennedy Space Center from 1979 to 1985 suggest that Florida scrub-jay response varies among plant communities. Florida scrub-jays decreased significantly during this time in flatwoods communities but not in coastal scrub or coastal strand; variation was high in this study and sample sizes were relatively small [88].
Florida scrub-jays are not capable of long-term survival in areas where fire is excluded [23,106,145]. Increased shrub height and tree cover associated with reduced fire frequency in fragmented habitat was likely the major contributor to a 34% decline over 10 years in 3 metapopulations in Brevard County [35]. At Savannas Preserve State Park, the Florida scrub-jay population began declining as time since fire increased, with a 22% decline occurring between postfire years 14 and 16 [45]. At Archbold Biological Station, the annual variation in fledgling and yearling production was greater in unburned than burned habitat. The greater fluctuation suggests that populations in marginal habitat are more vulnerable than populations in optimal habitat [61]. A simulation based on data from Florida scrub-jays in unburned habitat of Archbold Biological Station predicted population declines of 25% every 5 years [23].
Although Florida scrub-jays may select burned areas for nesting, the relationship between burned areas and nest success is unclear. Florida scrub-jays selected (P<0.001) burned habitat for nesting on the Ocala National Forest, with 68% of nests occurring in burned areas that comprised only 6.6% of the study area (Table 3). Nest success during the incubation stages was greatest in areas less than 5 years old and in areas 16 to 20 years old. The authors speculated that lower nest success in 6- to 15-year-old stands could be explained by greater density of Florida scrub-jays, low food availability, and/or increased predator densities. Stand age was not associated with nest success during the nestling stage [67]. Nest success was similar in Florida scrub-jay habitat at Archbold Biological Station, which is primarily fire-maintained scrub, and unburned scrub at Placid Lakes [134].
Table 3. Distribution of Florida scrub-jay nests in sand pine scrub stands ≤20 years old in the Ocala National Forest based on method used to regenerate sand pine and the availability of each stand type. Distribution of nests was different from that expected based on site availability (P<0.001) [67]. Reforestation method Percent of nests Percentage of the area treated with each method No site preparation 17.5 33.7 Seed only 7.7 28.7 Wildfire burn 39.3 5.1 Post-harvest burn 28.6 1.5 Chop and seed (burned or not) 6.9 30.9Influence of fire characteristics on Florida scrub-jay response: Frequency of fire influences Florida scrub-jay response. Due to the high frequency of wildfire in oak-palmetto communities, Florida scrub-jays may be more vulnerable in these communities than in oak scrub communities at Kennedy Space Center [19]. In areas of Kennedy Space Center where fire was introduced after being excluded for >30 years, preliminary results suggested a trend for lower abundance of Florida scrub-jays on transects burned more than once in a seven year period than those burned less frequently [88].
Growing season fires may have less direct impact on Florida scrub-jays than winter fires, because they allow for territory shifts while acorns are still available for caching and before hawk migration [146]. However, because mortality may occur at the nest, prescribed burns at Archbold Biological Station are typically avoided while Florida scrub-jays are nesting in March and April [91] (see Timing of breeding, nesting, and early development).
Florida scrub-jay populations have declined following large and uniformly severe fires at Kennedy Space Center [31,32,88]. From 1988 to 2005, large, severe fires converted territories with optimal scrub height to territories with short scrub, which cannot maintain Florida scrub-jays [29] (see Postfire succession and habitat quality). Large, widely distributed Florida scrub-jay populations at Kennedy Space Center typically recover from such fires in a few years, whereas small fragmented populations may not recover from such fires (Breininger unpublished data cited in [29]). Preliminary data following the reintroduction of fire at Kennedy Space Center suggest that extensive fires led to declines in Florida scrub-jay populations over the 6-year study period [88].
Postfire succession and habitat quality: Oak scrub provides optimal Florida scrub-jay habitat for a limited period, typically sometime between 5 and 20 years following disturbance [21,27,146], depending on weather, site characteristics (see Scrub height), community composition (see below), and location [32,46]. For instance, recovery on the Atlantic coast is typically (though not always) faster than at interior sites along the Lake Wales Ridge [17,110,116] so habitat may be optimal earlier in succession in coastal areas. The duration habitat remains optimal may be short in the absence of disturbance. Table 4 shows the probabilities that 10-acre plots will transition from one height class to another in 1 year with and without fire. Habitat of optimal height develops into mixed or tall habitat after about 3.7 years in the absence of disturbance, but prescribed burning does not guarantee that short and optimal habitat remain in these height classes. Even when you burn an optimal-height stand there is a 14.8% chance it will still grow enough in 1 year to reach a mixed height class. The transition probabilities for burned areas were based on a smaller sample size and have larger standard errors [78]. For fire responses of plant species common to scrub communities occupied by Florida scrub-jay see Abrahamson and others [2,4] and the FEIS reviews of turkey oak, sand pine, and saw-palmetto.
Table 4. Probability of transitioning from one habitat height class to another (within 1 year) with and without prescribed burning [78] Habitat height class Short Optimal Mixed Tall Burned Unburned Burned Unburned Burned Unburned Burned Unburned From short to 63.3% 38.3% 30.0% 51.7% 6.7% 10.1% 0 0 From optimal to 14.8% 1.2% 70.4% 73.2% 14.8% 25.6% 0 0 From mixed to 3.6% 0 0.8% 0 94.6% 99.7% 0.8% 0.3% From tall to 0 0 0 0 11.4% 3.1% 88.6% 97.0%Generally, it takes from 3 to 12 years after fire for regenerating vegetation develop into high-quality Florida scrub-jay habitat, although there are cases where fire improved Florida scrub-jay habitat quality in the short-term [1], for instance, when pine cover was substantially reduced [16]. Florida scrub-jays often occupy sand pine scrub on the Ocala National Forest as early as 2 (Faulhaber 2012 personal communication [57]) to 5 years after clearcutting [46]. In a sand pine woodland on the Ocala National Forest, Florida scrub-jays began occupying stands 5 to 7 years after a severe wildfire and salvage logging [69]. In oak scrub the growth rate is variable ([52], Schmalzer and Adrian 2001 cited in [110]), and it may take 4 to 12 years after fire for scrub to reach heights optimal for Florida scrub-jays [17,52,110]. Florida scrub-jay populations at Kennedy Space Center declined in open oak scrub for 1 to 8 years following extensive fires due to the short stature of the recovering vegetation [27,32]. Several studies at Kennedy Space Center found that scrub had not reached heights optimal for Florida scrub-jays 3 to 6 years after fire [27,68,110,115,116]. In Brevard County, Florida, scrub-jays in territories burned <3 years previously and composed of short (<4 feet, 1.2 m) scrub had the lowest Florida scrub-jay survival of all vegetation height classes [29]. For the first 3 to 5 years after fire in oak scrub at Archbold Biological Station, there was not enough cover or acorns to support Florida scrub-jays [146]. According to the Nature Conservancy, recovery of Florida scrub-jay habitat takes 3 to 5 years or longer on sites with infertile soil [130].
Because extensive areas of recently burned scrub do not sustain Florida scrub-jay populations, burning large areas on short fire-return intervals can be detrimental. Short intervals may fail to allow oaks sufficient time to grow to heights optimal for Florida scrub-jay [46,115]. Fire frequencies of 2 to 3 years in scrubby flatwoods and oak-palmetto typically result in short oaks that do not bear acorns [145] and may encourage increased palmetto dominance [115,145].
The time required for recovery of habitat structure varies with community type, whereas species composition changes little after fire, even in frequently burned areas, because herbs and shrubs in oak and flatwoods communities commonly sprout after fire ([1], Schmalzer and others 2003 cited in [29]). At Kennedy Space Center, saw-palmetto had nearly returned to preburn cover in a year, while oak cover had not recovered in 3 years [115]. At Archbold Biological Station, acorn production following fire varied across species; Chapman oak and sand live oak produced acorns the year following a May prescribed fire, while myrtle oak and turkey oak produced acorns 4 years following fire [4]. At Kennedy Space Center, results of prescribed fires from 1994 to 2004 suggested that burning oak scrub at least once every 5 years would increase habitat quality compared with less frequent burning. This trend was not observed in flatwoods [30].
Openings in scrub vegetation, which are an important component of Florida scrub-jay habitat, may close quickly following fire. Fire exclusion compounds this problem, making it difficult to restore openings in overgrown habitat [17], especially in scrubby flatwoods in coastal areas (Faulhaber 2012 personal communication [57]). In oak scrub of Kennedy Space Center that was cut and burned, openings often lasted less than 2 years and the canopy closed before shrubs grew to optimal height for Florida scrub-jays [37]. In mixed oak-palmetto at Kennedy Space Center, bare ground cover was <2% within 3 years after fire [110]. Xeric scrub retains its openings longer [17], and closing of sandy openings in sand pine scrub on the Ocala National Forest was described as gradual [36]. Frequent fires in undisturbed flatwoods and the possibility of hotspots from limbs and needles may explain the fact that openings in a scrubby flatwood site persisted longer than an oak scrub site at Kennedy Space Center [37]. Growing-season fires [52], burning downed logs and snags [16], and piling and burning to produce hot spots [111] have been suggested as possible ways to restore openings in scrubby vegetation. The area of openings created by burning piled fuels was only reduced by 50% 7 years after fire on the Shiloh site at Kennedy Space Center [111]. Openings can also be restored by repeated burning, which is sometimes accomplished by starting fires in more flammable neighboring vegetation, such as mesic flatwoods [17].
As scrub vegetation ages it becomes unsuitable for Florida scrub-jays [5,24,29,89,144,146]. This can occur as early as 10 to 15 years after cutting and burning sand pine stands on the Ocala National Forest [46] and as late as 20 years in oak scrub at Kennedy Space Center [21,27] and Archbold Biological Station [146]. The ability of Florida scrub-jays to remain in vegetation that was unburned for over 40 years at Archbold Biological Station may have been influenced by the high numbers of Florida scrub-jays and the availability of optimal habitat nearby. However, about 20 years after fire, reproductive success and survival of adults and juveniles began to decline [146]. The Florida scrub-jay population began to decline in the 1970s in a fire-excluded area of Archbold Biological Station; in the 1980s the area was abandoned [61]. In areas of Archbold Biological Station burned twice during this approximately 15-year period, abundance of Florida scrub-jays fluctuated without an obvious trend [144].
Characteristics typical of fire-excluded areas with poor Florida scrub-jay habitat quality include increased tree or scrub height [17,46,47,134,145], a loss of openings in the canopy [17,146], increased ground cover (see Openings), reduced oak density (see Oak scrub) [47], and increased tree density (see Tree cover) [46,146]. In Brevard County, landscapes where fire did not occur transitioned from optimal scrub habitat to areas where scrub was too tall to provide high-quality Florida scrub-jay habitat [29]. A model based on data from Kennedy Space Center [54] predicted that vegetation would reach 5.5 feet (1.7 m), which is too tall to provide optimal habitat, by 20 years after fire [17]. Oak-palmetto stands at Kennedy Space Center that had not burned in 25 years were dense, and shrub height typically ranged from 7 to 10 feet (2-3 m) tall [108,116]. Shrubs were as tall as 16 to 20 feet (5-6 m) in some areas [108]. In contrast, fire exclusion from flatwoods communities may allow for a scrubby structure that is more favorable to Florida scrub-jays than regularly burned flatwoods [88]. However, this effect is unlikely to persist. Florida scrub-jays in unburned late-successional scrubby flatwoods at Archbold Biological Station had mortality that exceeded recruitment [61]. For information on other impacts of fire exclusion, see FIRE REGIMES.
Federal legal status:
Threatened [132]
Other status: Information on state- and province-level protection status of animals in the United States and Canada is available at NatureServe, although recent changes in status may not be included.
Other management information: The Florida scrub-jay is in decline and subject to continuing threats, including loss of optimal habitat. Several population and Habitat management options have been proposed to address these concerns.
Habitat management: Increasing the amount of high-quality habitat is critical to the recovery of the Florida scrub-jay. They are dependent on large expanses of scrub [133], and the amount of scrub habitat available strictly limits the number of Florida scrub-jay territories [146]. Modeling Florida scrub-jay populations based on the habitat available in 1992-1993 suggests that only 3 metapopulations were likely to remain viable without further habitat acquisition. Habitat acquisition would "greatly" or "moderately" reduce risk of falling below 10 pairs in 4 relatively stable metapopulations and in 11 of 14 highly vulnerable metapopulations [124]. A population model of Florida scrub-jays indicated that 30 to 40 contiguous territories are needed to achieve a 90% chance of the population persisting for 100 years [61]. Mapping techniques used to identify potential Florida scrub-jay habitat and associated population sizes were discussed by Breininger [22]. As of March of 2007, over 280,000 acres (113,300 ha) of scrub habitat had been purchased and protected [133]. An umbrella habitat conservation plan has streamlined the process for alterations to property on small lots occupied by Florida scrub-jays that are not part of viable populations. In 2007 this was expected to generate enough mitigation funds over 7 years to purchase an additional 29,856 acres (12,080 ha) [131]. Analyses of habitat conservation plans that describe their function and limitations are provided by James [76] and Watchman and others [135].
The quality of available habitat is critical because of its influence on the demographic performance of Florida scrub-jays (see Preferred Habitat). For instance, the 35% population decline per decade observed in Brevard County could not be explained by the 5% loss of habitat alone [35]. Modeling of a Florida scrub-jay population with demographic rates observed in optimal habitat predicted a 5% chance of the population falling below 100 pairs within 50 years, while a population modeled with the demographic rates observed at Happy Creek in the mid-1990s predicted a 90% chance of falling below 100 pairs in the next 50 years [16]. As of 2003, the overgrown Happy Creek site was declining, likely because too few territories had optimal habitat to offset declines in sink territories [24]. Other simulations of Florida scrub-jay populations in Brevard County found that only those in optimal or slightly overgrown habitat are sustainable [106]. Data from Archbold Biological Station suggest that risk of extinction can be reduced through improvements to habitat quality [23]. In contrast, simulations of implementing an optimal management strategy based on vegetation height data from Kennedy Space Center did not predict increasing Florida scrub-jay populations [78]. A focus on territory-scale restoration is needed to ensure that most territories have all the required structural features [24]. Treatments recommended to improve habitat quality include prescribed burning. See Recommendations for fire characteristics for details.
Preserving large expanses of scrub with minimal fragmentation [21,61,146], minimizing the distance between optimal patches of habitat (see Dispersal) [16,21,43,126], and improving matrix quality (see Landscape features) [14] are common Florida scrub-jay Habitat management recommendations. Fitzpatrick and others suggest that on average, 750 acres (300 ha) of periodically-burned oak scrub are required to support a viable Florida scrub-jay population. This size area would allow for 30 contiguous territories at 25 acres (10 ha) each. Smaller populations are adequately protected if they occur within 3 to 5 miles (5-8 km) of a population supporting at least 30 territories [61]. Because of Florida scrub-jays' limited dispersal abilities, preserves more than 7.5 miles (12 km) apart without any Florida scrub-jay habitat in between are fully isolated from one another. Distances of 5 miles (8 km) and farther significantly restrict dispersal [146]. Stith [126] suggests removal of dispersal barriers and research into methods for facilitating dispersal such as creating partially cleared rights-of-way between patches. Boyle [14] also recommended managing the matrix to maintain communities readily traversed by dispersing Florida scrub-jays. Matrix quality can be improved by minimizing interspersion [27] and boundaries between scrub and roads, areas of human development (see Preferred Habitat), and dense forest (see Tree cover) [16,61].
Concerns have been raised over the impacts of managing areas for a single species and the assumption that other scrub species will also benefit [93]. A long-term multi-species monitoring plan may address this concern by providing information that can be incorporated into future management decisions [128]. Variable management prescriptions (see Recommendations for fire characteristics) also address aspects of this concern.
Historical and current land uses influence Florida scrub-jay habitat quality and the ease of restoration. For instance, creating scrub in areas used as citrus groves is difficult [114] while areas of periodically-burned pastures responded well to restoration efforts at Tel-4 [53]. Regenerating pasture that borders scrub has conservation value for Florida scrub-jays as an open matrix landcover type without the risks associated with dense forests or suburbs. Regenerating pastures may also serve as dispersal corridors and ignition sources. Because of this, acquisition and restoration of pasture near native scrub was recommended in cases where large tracts of scrub are not available [49]. At Kennedy Space Center, soil disturbance due to vegetation clearing resulted in establishment of trees on flatwoods sites and occurrence of sandy openings in disturbed xeric scrub [53]. Trees in disturbed flatwoods communities likely reduce the suitability of habitat in these areas, while sandy openings could improve habitat quality for Florida scrub-jays in disturbed xeric scrub. History of fire exclusion makes restoration with fire alone difficult (see Impacts of fire exclusion) and often necessitates mechanical treatment prior to burning (see Restoration of overgrown scrub).
Timber harvesting is not used to manage Florida scrub-jay habitat at most sites, but is used on the Ocala National Forest. Sand pine is managed as Florida scrub-jay habitat using clearcuts of no more than 25 acres (10 ha) performed on a 50-year rotation [67]. Oaks in this community reach 3 to 7 feet (1-2 m) tall within 3 to 5 years of harvesting the sand pine. If the oaks are dense [46], Florida scrub-jays will occupy these areas for up to 20 years after harvesting; after 20 years, sand pine reaches heights and densities that reduce Florida scrub-jay habitat quality. In other areas occupied by Florida scrub-jays, sand pine is actively suppressed [67].
Population management goals generated to assist in the recovery of the Florida scrub-jay identify minimum population sizes and maximum distances between populations. Based on dispersal information and population viability analysis, Stith and others [125] suggest the following: maintain the 3 core metapopulations above 400 pairs each, preserve metapopulations with habitat that supports more than 10 pairs, preserve twice as much Florida scrub-jay habitat in viable populations as that lost in areas that do not have enough habitat to support 10 pairs, ensure that patches of habitat within a metapopulation are no more than 7.5 miles (12 km) apart, and ensure that no subpopulation is more than 5 miles (8 km) from occupied habitat. To preserve the remaining levels of genetic variation it is necessary to achieve sustainable metapopulations throughout the Florida scrub-jay's distribution, especially in small populations near the edge of the current range [43,92]. For details on the role of Habitat management to achieve these goals, see Habitat management. For information on the use of fire to improve habitat quality, see Fire Management Considerations.
Although stable or growing populations are ideal, declining subpopulations, or sinks, may benefit Florida scrub-jay metapopulations. Individuals migrating from sinks occasionally become breeders in optimal territories [24], can offset losses in larger populations [21], and provide a source of colonizers for restored habitat [21,129]. In Sarasota County, 83% of female suburban Florida scrub-jays became breeders by colonizing a recently restored scrubby flatwood. No other group of females became breeders by establishing in the restored area [129]. In cases when large populations are at capacity, sink populations provide vacancies for dispersing Florida scrub-jays. This buffering of larger and typically better performing populations by the smaller, typically declining populations could contribute to the longevity of the metapopulation as a whole (Howe and Davis 1991 cited in [126], Pulliam 1988 cited in cited in [22,27]). In addition, habitat supporting population sinks may transition into [24] or be restored to [14] high-quality habitat.
Florida scrub-jay population recovery and/or establishment in restored habitat may be slow [17,23]. Short dispersal distances (see Dispersal) and little recruitment in many source populations (see Population trends) limit the number of potential colonizers [130,133]. For instance, in the late 1990s there was a lack of male dispersal into restored areas in the Valkaria area of southern Brevard County [17]. Helpers are often the first to occupy restored areas [129]. This could reduce the occurrence of delayed breeding [46], since more breeding vacancies lead to earlier breeding [21,28,34]. This reduction in helpers could reduce reproductive success in source areas (see Cooperative breeding). In addition, Florida scrub-jays may not always recognize the habitat potential of restored areas [17] and may cue on occupied habitat to a greater extent than high-quality habitat [126]. Despite these issues, Florida scrub-jays have established in restored habitat in areas of Volusia, southern Brevard, Indian River, and Sarasota counties where there was a source of colonizers near restored habitat [133]. At Lyonia Preserve in Volusia County, Florida scrub-jays established within months of vegetation removal, probably because they occurred in a nearby area with declining habitat quality [130].
Translocation of Florida scrub-jays into restored areas has shown some success. A translocation experiment at Rookery Bay National Estuarine Research Reserve produced a population with nest success, juvenile survival, and adult survival similar to that at Archbold Biological Station beginning about 2 years after the first translocation. However, nearly half the Florida scrub-jays that were introduced were lost within 8 weeks, and emigration and mortality of females fledged on the site resulted in a male-biased sex ratio [99] that persisted for several years after the translocation [146]. Translocation is not a viable option for managing existing populations because properly managed translocation sites are rare, initial loss of translocated Florida scrub-jays is high, and source populations may be impacted [99].
As of 2012, the biggest threat to Florida scrub-jay is a loss of high-quality habitat, which is caused primarily by fire exclusion [133,146]. A 1992-1993 rangewide survey found that 64% of scrub patches occupied by Florida scrub-jay were in fire-excluded, "overgrown" scrub (i.e., too tall and/or dense to maintain viable populations of Florida scrub-jay). Overgrown scrub becomes progressively less suitable (see Postfire succession and habitat quality) and more fire resistant (see Impacts of fire exclusion) with time. Thirty percent of occupied scrub patches were in suburban areas [125]. These areas provide low-quality habitat partly due to the reduced fire frequency associated with fragmentation [56]. In 1995 and 1996, most of the Florida scrub-jay habitat in Brevard County was overgrown due to fire exclusion. Researchers classified 2,879 acres (1,165 ha) as "slightly overgrown", 6,788 acres (2,747 ha) as "moderately overgrown", and 3,398 acres (1,375 ha) as "very overgrown". Only 235.7 acres (95.4 ha) were in optimal condition (see Preferred Habitat) [106]. As of 2003, 38% of scrubby flatwoods and 83% of sand pine scrub at Archbold Biological Station were due or overdue for burning based on their modal fire-return interval [75]. The intensive management required to keep scrub on public lands from degrading (see Fire Management Considerations) has been difficult to implement, and scrub communities on private lands are rarely managed for maintaining high-quality Florida scrub-jay habitat [133].
Direct loss of habitat also threatens Florida scrub-jay populations [101,146]. From 1920 to 1990, over 65% of scrub habitat was converted to other land cover types in the Indian River Lagoon watershed [55]. From 1989 to 2003, there was a 19% decline in land cover classes potentially suitable for Florida scrub-jays (Burns 2006 cited in [133]), and the U.S. Fish and Wildlife Service expects future habitat destruction with increasing human population size [133]. Continued acquisition of scrub communities by conservation and land management organizations and region-wide Habitat Conservation Plans are the main strategies for addressing this issue (see Habitat management).
Although there is concern regarding potential impacts of hurricanes on Florida scrub-jays and their habitat (e.g., [126]), available information suggests neutral [21] or positive impacts of hurricanes [133]. A 1995 hurricane that hit the southern barrier island of Brevard County, Florida, did not increase Florida scrub-jay mortality [21]. An environmental assessment of the Umbrella Habitat Conservation Plan describes minimal impacts on Florida scrub-jays from Hurricane Charley and the hurricanes of 2004 and 2005. It also includes evidence for increased occurrence of Florida scrub-jays following heavy damage to pine canopy cover that resulted in increases in oak scrub. In the short-term, however, reductions in acorn production and oak cover could be detrimental [133]. Managing for potential negative impacts of hurricanes focuses on maintaining or increasing population size and availability of high-quality habitat [23].
Inbreeding may threaten Florida scrub-jays. Based on an investigation of populations throughout peninsular Florida, Coulon and others [43] concluded that substantial genetic variation has been lost through the extinction of isolated populations. In Brevard County, there is limited gene flow and some level of inbreeding is occurring [82].
The tameness of Florida scrub-jays, especially in areas where they are fed by humans, makes them vulnerable to shooting [146].
The character of high-quality Florida scrub-jay habitat–composition, structure, and spatial arrangement of vegetation–is highly specific. Well-drained oak scrub provides high-quality habitat [35,146]; however, large expanses of well-drained scrub are not necessarily required for viable Florida scrub-jay populations [32]. Florida scrub-jay populations are generally viable in oak-dominated scrub communities (see Plant Communities) where each territory has at least 0.75 to 1.0 acre (0.3-0.4 ha) of 3- to 7-foot tall scrub [32,35], less than 1 acre of tall scrub [24], scattered open areas, and few trees (see Structural features). Good-quality habitat also borders open, native vegetation (see Landscape features). Oak scrub of this nature historically developed under a regime of frequent fires (as often as every 5 to 10 years). These fires were often patchy, with burned patches usually smaller than Florida scrub-jay territories (see FIRE REGIMES for details).
Presence of Florida scrub-jays does not necessarily indicate good-quality habitat. In some cases, areas with Florida scrub-jays cannot support a population over the long-term [26,32], while in optimal habitat recruitment generally exceeds mortality [24]. Florida scrub-jays will defend territories in marginal habitat, as was the case at Happy Creek from 1988 to 2000 [24]. Optimal habitat was selected by Florida scrub-jays at Kennedy Space Center, suggesting that these are the first areas occupied when Florida scrub-jays are at low densities [24,27]. In contrast, a lack of colonization of high-quality habitat at Avon Park Air Force Range led Stith [126] to suggest that dispersing Florida scrub-jays may cue on the presence of other Florida scrub-jays more than aspects of habitat quality when establishing territories.
In most cases, suburbs do not provide good Florida scrub-jay habitat. A population of Florida scrub-jays surrounded by urban areas on a barrier island in southern Brevard County declined at a faster rate than typical for low-quality unburned scrub [21]. Mortality from vehicle collisions [21,100,146] and predation by domestic cats [21,146] (see Survival) have been suggested as possible causes of poor demographic performance in areas of human development. Human-provided food may contribute to reduced reproductive success (see Diet). Due to these and other issues, territories near human development often have mortality rates that exceed reproduction [12,21,100]. Florida scrub-jays in preserve areas of Sarasota [129] and Highlands [12] counties did not disperse into nearby suburban Florida scrub-jay populations. Despite these general trends, fledgling success in suburbs has been good in some years [142], and territories next to suburban development in Brevard County with optimal scrub height and openings had greater reproduction than mortality. Although these conditions rarely occurred, the researchers suggest maintaining optimal habitat conditions in edge territories to increase their potential to contribute to population increases [35].
www.lauraerickson.blogspot.comLandscape features: Florida scrub-jay territories are comprised of a mosaic of oak scrub and openings within a matrix (area surrounding Florida scrub-jay habitat) of rarely- or never-used vegetation [27,35,126]. Potential population sizes may be greatly underestimated if medium to small patches of open scrub habitat imbedded in non-habitat communities, such as mesic flatwoods, are not included [22,32,35].
Although rarely used, matrix vegetation influences the quality of Florida scrub-jay habitat patches [21,26,27,49]. In Brevard County, Florida scrub-jay use of scrub patches was influenced by the landscape cover surrounding them; matrix habitats of flatwoods and palmetto allowed for increased capacity in areas where scrub was limited [14]. Open, flammable communities away from human development apparently make the best matrix vegetation because they provide increased distance from forests (see Tree cover), increased opportunity for dispersal, increased occurrence of native prey species (see Diet) [27], potentially fewer predators (see Tree cover), shortened fire-return intervals within the oak scrub [16,27,35] (see Fire Regime), and reduced detrimental impacts associated with suburbs (see Preferred Habitat). The openness and flammability of pastures led Davison and Fitzpatrick [49] to recommend their consideration in habitat conservation planning.
Structural features: Viable Florida scrub-jay populations are comprised of Florida scrub-jays occupying many territories that each have at least 0.75 to 1.0 acre (0.3-0.4 ha) of medium-height scrub (see Scrub height) [24,32], less than 1 acre of tall scrub [24], scattered open areas [14,27,126], and less than 20% pine cover [26,27,46]. Sites occupied by Florida scrub-jays at the Kennedy Space Center had greater percent oak cover (P=0.002), percent open space (P=0.008), and distance to forest (P=0.004) than unoccupied sites [27]. Variation in Florida scrub-jay occupancy in Brevard County was explained mainly by pine canopy, open space, and scrub height [14]. Habitat suitability indices developed in 1992 scored vegetation based on several factors and defined good-quality Florida scrub-jay habitat as being over 330 feet (100 m) from forest vegetation and having >50% oak cover, <15% pine cover, an average shrub height of 4 to 5.5 feet (1.2-1.7 m), and 20% to 50% open space or near proximity (<330 feet (100 m)) to a ruderal edge (Breininger 1992 cited in [26]). Areas with the highest values based on these measures were preferred by Florida scrub-jays for nesting and had the highest fledgling production [26]. These indices were also correlated with demographic performance at Tel-4 (r=0.87; P<0.001) [54] and at Happy Creek when averaged over 5 years (P<0.001) [26]. Florida scrub-jays had greater genetic diversity in vegetation with more than 50% oak cover that was 4 to 5.5 feet (1.2-1.7 m) tall and had open sandy areas [82].
Scrub height: Medium-height scrub (4 to 5.5 feet (1.2-1.7 m) tall) was positively associated with Florida scrub-jay demographic variables in several studies in Brevard County [24,29,32,35], although 1 study found that scrub height was not important to nest success [37]. At the Happy Creek site the only territories in which recruitment potential exceeded breeder mortality were those with at least 0.32 acre (0.13 ha) of medium-height scrub, no more than 1 acre (0.4 ha) of tall scrub (>5.5 feet (1.7 m) tall), and the remainder of the territory comprised primarily of short (<4 feet tall) scrub. In territories meeting these habitat criteria, demographic performance (P=0.001) and fledgling survival (P=0.039) were significantly greater than in territories in marginal habitat. Marginal habitat was typically due to large (>1 acre) patches of tall scrub [24]. At Tel-4, Florida scrub-jays in territories with 2.2 to 3 acres (0.9-1.2 ha) of medium-height scrub had better average demographic performance/pair than territories with either more or less medium-height scrub. Territories with less than 0.7 acre (0.3 ha) of medium-height scrub typically had mortality rates that exceeded recruitment [32]. In 3 metapopulations along the Atlantic Coast, territories comprised of short and medium-size oaks had greater yearling production than breeder mortality. Well-drained oak scrub ridges had lower demographic performance than territories with a mixture of scrub ridge and palmetto-scrub vegetation, possibly because of lower flammability and consequently taller shrub heights on scrub ridges [35]. Another extensive study of Florida scrub-jays in coastal Brevard County found that survival rates ranged from 71% in short scrub habitat to 82% in medium-height oak scrub. Survival in tall scrub was intermediate to these values [29]. In contrast, nest success at Kennedy Space Center may have been influenced more by a lack of openings or the occurrence of nocturnal snakes than by shrub height [37].
Height of scrub communities is influenced by time since disturbance. In 1982 and 1983 on the Ocala National Forest, a significantly greater proportion of sand pine stands that regenerated from 1972 to 1978 (43%) were occupied by Florida scrub-jays than stands that regenerated from 1965 to 1971 (22%, P<0.01). Once the sand pines reached 9.8 feet (3 m) tall or 50% cover, the stands no longer provided good-quality Florida scrub-jay habitat [46]. See Postfire succession and habitat quality for details regarding postfire habitat quality.
The timeframe in which successional vegetation provides optimal Florida scrub-jay habitat is influenced by several factors. These include disturbance history [46], plant community composition [30,77], site characteristics [30,46], and weather [46]. Optimal-height habitat was estimated to remain optimal for 3.7 years without disturbance at Kennedy Space Center [78]. Scrub communities with relatively high proportions of sandhill oak could provide habitat for a longer period than those comprised of other species because sandhill oak has a relatively short lifespan and reaches a median height of 6.6 feet (2 m) despite stands being up to 40 years old [77]. The level of the water table [30], soil nutrients, rainfall, and the severity and extent of previous fires [46] also influence if and when vegetation on a site provides high-quality Florida scrub-jay habitat.
Tree cover: Vegetation with high tree cover provides poor quality Florida scrub-jay habitat and reduces quality of adjacent habitat [26,27]. At Avon Park Air Force Range in central Florida, Florida scrub-jays selected territories with low tree cover, and Florida scrub-jay group size was generally larger in territories with lower tree cover. Florida scrub-jays in areas with more than 20% to 30% tree cover within or adjacent to territories had poor demographic performance [126]. In a model of Florida scrub-jay occupancy for Brevard County, increasing pine canopy cover was a key indicator of poor-quality habitat [14]. Nest success at Kennedy Space Center declined with proximity to forest edges, and daily survival increased in areas with greater oak cover and greater distance to the nearest forest edge [37]. Recent analyses suggest that high-quality habitat has no more than 1 tree/acre, and that habitat within 1,000 feet (300 m) of forested areas may provide low-quality Florida scrub-jay habitat (Burgman and others 2001 as cited in [81]). Nest survival was reduced within 2,400 feet (730 m) of forests at Kennedy Space Center (Carter unpublished cited in [81]). In the Ocala National Forest, Florida scrub-jays occupy sand pine communities where oaks are dense and sand pines are short (9.8 feet (<3 m)) and comprise <50% cover [46]. Patches of good-quality scrub less than 2.5 acres (1 ha) were occupied by Florida scrub-jays at Kennedy Space Center, except when they were surrounded by forests [27].
Florida scrub-jay's poor performance in areas with high tree cover may be related to predators. Many avian predators are more common in forests [126] and may be harder to detect in forested communities ([14], Breininger and others 1995 cited in [26]). Dense forest growth may also provide cover for ground predators, increasing the likelihood of successful ambush of Florida scrub-jays and their nests [45]. Snakes that prey on Florida scrub-jay nests often use forest edges (reviewed in [37]). Carter and others [37] suggest that habitat changes due to fire exclusion at Kennedy Space Center may have increased the density of snakes.
Openings: Oak scrub communities that provide high-quality Florida scrub-jay habitat have a complex mosaic of openings comprising less than 50% of the area. Openings are areas with bare sand [26,146] and open canopies [17,37]. Several predators are associated with dense vegetation (see Tree cover). In contrast, openings likely allow for easier predator detection [16,37,144] and are used for caching acorns (see Diet). Florida scrub-jay use increased as open space increased from 0% to 30% at Kennedy Space Center [27]. At Avon Park Air Force Range, Florida scrub-jay territories had more open sand than areas outside of Florida scrub-jay territories [126]. Nest success in the scrubby flatwoods vegetation at Tel-4 was greater than in the scrub at Happy Creek. The difference in nest success is likely related to the dense nature of the scrub community at Happy Creek, which could make detection of predators more difficult [37]. It has been suggested that the simple edges and dense scrub at Happy Creek provide lower quality habitat than the complex mosaic of openings at Tel-4 [26]. Simple edges were systematically patrolled by predators of loggerhead shrikes (Lanius ludovicianus) at Archbold Biological Station (Yosef 1994 cited in [54]). Carter and others [37] recommend more research into the relationship between openings and Florida scrub-jay nest success. Natural openings are apparently of higher quality than ruderal areas [26], but the reasons for this are not well understood.
Nest site characteristics: Florida scrub-jay nests are off the ground [13,134,146] and well concealed from above [134,138,146]. In suburban habitat at Placid Lakes, nests were commonly associated with greenbriar (Smilax spp.), which seemed to increase concealment [13,134]. Nests at Archbold Biological Station were built at an average of 3 feet (0.9 m) above ground and ranged from 1.6 to 8.2 feet (0.5-2.5 m) above ground [146]. Nest trees at Placid Lakes averaged 10.2 feet (3.1 m) tall, and nest trees at Archbold Biological Station averaged 7.2 feet (2.2 m) tall [134]. Nests at both Archbold Biological Station and Placid Lakes occurred at greater heights in taller trees. This trend was stronger in the suburbs, where nests in high shrubs seemed more susceptible to wind damage [13]. Nest sites are almost never reused [146].
Reproductive output: Based on over 20 years of data from Archbold Biological Station, 88% of breeders produced at least 1 fledgling, but 70% of fledglings were produced by 30% of breeders. On average, 49% of Florida scrub-jay nests produced at least 1 fledgling, although annually this ranged from 29% to 75%. Average annual production of independent young was 1.12 per pair [146]. At Kennedy Space Center, only 35% of nests successfully produced at least 1 fledgling, with 94% of failures due to predation [37]. On the Ocala National Forest, pairs without helpers produced an average of 1.71 fledglings, and pairs with helpers produced an average of 2.24 fledglings. Predation was the likely cause of the low nest success, with 64% of 13 video-monitored Florida scrub-jay nests being partially or totally depredated [66].
Reproductive success of Florida scrub-jays is variable and influenced by several factors including presence or absence of helpers (see Cooperative breeding), annual variation [67,146], experience of breeders, duration of pair bond [10,141,146], timing of laying and hatching [37,67], and habitat (see paragraph below). Annual variation is substantial. In optimal habitat at Archbold Biological Station, average annual reproductive success ranged from 1.05 to 2.71 fledglings/pair [61]. Rainfall has been shown to influence nest success, although in different ways at different locations [37,141]. It is not likely that rainfall's effects on nest success are due to its influence on food availability because few nestlings die from starvation [37]. Inexperienced breeders had lower reproductive success than experienced breeders [28,46], and established pairs had better success than new pairs at Archbold Biological Station [141,146]. Nest success declined as the breeding season progressed at both Kennedy Space Center [37] and on the Ocala National Forest [67].
Some habitat attributes impact Florida scrub-jay reproductive output, while others have not been shown to have a significant influence. Table 2 shows several measures of reproductive output from sites of varying quality. Based on data from Archbold Biological Station collected from 1969 to 1984, lifetime reproductive success of Florida scrub-jays in unburned, overgrown habitat is 0.4 breeding offspring per individual, while in periodically burned habitat it is 1.1 breeding offspring per individual [59]. See Influence of fire on Florida scrub-jay demographics for more information. Data from the same area through 1994 show Florida scrub-jays in high-quality habitat produced an average of 7.4 fledglings, 4.2 independent young, and 2.2 yearlings over their lifetimes [146]. Stand age was an important influence on daily nest survival rate during the incubation phase on the Ocala National Forest (see Influence of fire characteristics on Florida scrub-jay response for details) [67]. Bowman [13] found that nest success was higher in oaks than in other vegetation at Placid Lakes and Archbold Biological Station. In contrast, an earlier study of these sites found species of shrub used for nesting did not have a significant influence on nest success [134]. Although differences were not significant, Florida scrub-jays in territories with a substantial component of palmetto had lower nest success [27] and produced fewer offspring [32] than those in open, oak-dominated territories. At Archbold Biological Station, nest success and yearling production of Florida scrub-jay nests in territories comprised of regenerating pasture bordering oak scrub were not significantly different from those in intact oak scrub [49].
Table 2. Comparison of average Florida scrub-jay demographic rates in 3 areas Demographic parameter Fragmented suburban populations in southern Brevard County [21]* Kennedy Space Center [28] Archbold Biological Station (1969-1986) [145] Tel-4 site (1989-1993) Happy Creek siteThe scientific name of Florida scrub-jay is Aphelocoma coerulescens Bosc (Corvidae) [9].
The Florida scrub-jay was elevated from subspecies status in 1995 [8]. Although rare, hybridization with blue jays has occurred [97].
SYNONYMS:
Aphelocoma coerulescens coerulescens Bosc
Territories/Density: Florida scrub-jays typically remain on a territory from the time they become breeders until their death. Territories are acquired in 1 of 4 ways. The most common for both sexes is to replace a lost breeder on a nearby territory. Another fairly common method is to "bud" off a portion of the natal territory into a new territory. More common in males than females is the direct inheritance of the natal territory following the death of breeders. In a few cases a new territory is established between existing territories or in unoccupied scrub. Habitat destruction, extensive fire, or, rarely, the loss of a mate results in Florida scrub-jays abandoning territories; the latter is more common among females than males [146].
Florida scrub-jays defend territories that typically range from 10 to 45 acres (4-18 ha) [61], with territory size in good habitat averaging about 23 acres (9 ha) [31,68,146]. The smallest average territory size reported was 6 acres (2.4 ha) just north of Archbold Biological Station [138], and the largest territory size reported was 119.6 acres (48.4 ha) at Kennedy Space Center [68]. Fitzpatrick and others [61] note that 23 acres is the average amount of useable oak scrub in a territory, and most territories contain additional patches of unused habitat. Territory size varies with group size, availability of supplemental food [146], community type [61,68,146], and, in some instances, density of Florida scrub-jays [24].
Due to space requirements, density of Florida scrub-jay territories averages about 4 to 5 territories per 100-acre (40 ha) area, with densities declining in scrub that is sparse or overgrown [146]. Minimum territory density for a stable population is 2.0 territories per 100 acres of optimal habitat, and maximum territory density is 6.5 territories per 100 acres [61].
Population growth may be affected by Florida scrub-jay density. There are many reasons that low densities could be detrimental to Florida scrub-jays, including fewer helpers to contribute to reproductive success (see Cooperative breeding), longer dispersal distances needed to find mates, and smaller populations being more vulnerable to extinction from stochastic events such as hurricanes [23] or disease epidemics. However, demographic performance per pair was highest at the lowest densities observed (2.0 pairs/40 ha) in oak-palmetto territories at Tel-4. The Florida scrub-jay population at this site was growing when densities were less than 2.8 pairs/40 ha, and declining at higher densities [32].
Les especies d'aves con nome común en llingua asturiana márquense como NOA. En casu contrariu, conséñase'l nome científicu o de la SEO.
Aphelocoma coerulescens,[3] conocida tamién como chara pechu rayáu o pega de les carbes,[4] ye una especie d'ave paseriforme de la familia Corvidae. Ye la única especie d'ave endémica del estáu de Florida y una de les 15 especies endémiques de los Estaos Xuníos.[5] Por cuenta de esto ye bien buscada polos observadores d'aves que viaxen dende tol país pa reparar esta especie. Sábese que tuvieron presentes na Florida como una especie común reconocible distinta por siquier 2 millones d'años,[6] posiblemente derívase del Aphelocoma californica.[7]
Mide d'ente 23 a 28 cm de llargor y pesa de 66 a 92 g, con un promediu de 80,2 g. La valumbu de ser 33 a 36 cm.[8][9] La cabeza la nuca y les ales son azules, la frente ablancazada, les partes inferiores abuxaes y el llombu gris, la cola ye llarga y de color azul. Les pates y el picu son negros.
Ye orixinariu d'Estaos Xuníos, atopándose solo nel estáu de Florida. El so hábitat natural son los breñales de Florida, un ecosistema qu'esiste namái nel centru de Florida y caracterízase pelos suelos probes en nutrientes, seques ocasionales y les frecuentes quemes forestales.
En dómines de cría reparáronse hasta seis ayudantes nel nial d'una pareya. Estos "ayudantes", que suelen ser machos adultos fíos de la pareya reproductora, tán preparaos dende un puntu de vista fisiolóxicu pa tener descendencia, pero inverten el so tiempu y enerxía n'alimentar a los sos hermanos y en defender el territoriu de la pareya reproductora (los sos padres). Anque'l ayudantes de cría llogren beneficios en términos d'eficacia biolóxica indireuta pol fechu d'ayudar a los sos padres, estos beneficios nun son tan importantes como los que llograríen si tuvieren la so propia descendencia. Sicasí, l'analís de la densidá poblacional y de la disponibilidad de territorios pa nidificar, indica que, nun siendo que un machu tenga un rangu de dominancia eleváu, nun va poder faese con un territoriu de nidificación nin defendelo contra les sos coespecíficos. Solamente'l ayudantes de cría qu'ocupen los rangu más elevaos dexen de ser ayudantes y llogren un territoriu cuando fina un vecín o unu de los sos padres .[10]
Esta páxina forma parte del wikiproyeutu Aves, un esfuerciu collaborativu col fin d'ameyorar y organizar tolos conteníos rellacionaos con esti tema. Visita la páxina d'alderique del proyeutu pa collaborar y facer entrugues o suxerencies. Les especies d'aves con nome común en llingua asturiana márquense como NOA. En casu contrariu, conséñase'l nome científicu o de la SEO. Aphelocoma coerulescens, conocida tamién como chara pechu rayáu o pega de les carbes, ye una especie d'ave paseriforme de la familia Corvidae. Ye la única especie d'ave endémica del estáu de Florida y una de les 15 especies endémiques de los Estaos Xuníos. Por cuenta de esto ye bien buscada polos observadores d'aves que viaxen dende tol país pa reparar esta especie. Sábese que tuvieron presentes na Florida como una especie común reconocible distinta por siquier 2 millones d'años, posiblemente derívase del Aphelocoma californica.
La garsa blava de bardissa de Florida[1] (Aphelocoma coerulescens) és un ocell de la família dels còrvids (Corvidae) endèmic de l'Estat nord-americà de Florida.
Habita zones de matoll de l'àrea central de la Península de Florida.
La garsa blava de bardissa de Florida (Aphelocoma coerulescens) és un ocell de la família dels còrvids (Corvidae) endèmic de l'Estat nord-americà de Florida.
Aderyn a rhywogaeth o adar yw Sgrech prysgwydd (sy'n enw benywaidd; enw lluosog: sgrechod prysgwydd) a adnabyddir hefyd gyda'i enw gwyddonol Aphelocoma coerulescens; yr enw Saesneg arno yw Scrub jay. Mae'n perthyn i deulu'r Brain (Lladin: Corvidae) sydd yn urdd y Passeriformes.[1]
Talfyrir yr enw Lladin yn aml yn A. coerulescens, sef enw'r rhywogaeth.[2]
Mae'r sgrech prysgwydd yn perthyn i deulu'r Brain (Lladin: Corvidae). Dyma rai o aelodau eraill y teulu:
Rhestr Wicidata:
rhywogaeth enw tacson delwedd Aderyn rhisgl Falcunculus frontatus Aradrbig Eulacestoma nigropectus
.JPG)
Aderyn a rhywogaeth o adar yw Sgrech prysgwydd (sy'n enw benywaidd; enw lluosog: sgrechod prysgwydd) a adnabyddir hefyd gyda'i enw gwyddonol Aphelocoma coerulescens; yr enw Saesneg arno yw Scrub jay. Mae'n perthyn i deulu'r Brain (Lladin: Corvidae) sydd yn urdd y Passeriformes.
Talfyrir yr enw Lladin yn aml yn A. coerulescens, sef enw'r rhywogaeth.
Der Florida-Buschhäher (Aphelocoma coerulescens) ist eine Singvogelart aus der Familie der Rabenvögel, die nur in Florida vorkommt.
Der Florida-Buschhäher hat eine Körperlänge von 28 Zentimetern. Der Hinterkopf, der Mantel, die Flügeloberseiten und der Schwanz sind leuchtend blau. Der Rücken, die Unterseite und die Stirn sind grau. Unterhalb des Kropfes ist ein dunkles Band. Die Ohrdecken sowie die Unterseiten von Flügel und Schwanz sind dunkel, ebenso die Iris, der Schnabel und die Beine.
Das Vorkommen des Florida-Buschhähers ist auf die mit Buschwerk bestandenen Regionen Floridas beschränkt. Sein bevorzugter Lebensraum befindet sich meist in einem Übergangszustand: Nach Bränden entstandenes Buschwerk, das größtenteils aus etwa drei Meter großen Eichen besteht und von kleinen Lichtungen durchsetzt ist.
Der Bestand der Art ist im 20. Jahrhundert auf Grund der Vernichtung seines Lebensraums um etwa 90 Prozent zurückgegangen. Er wurde 1975 von der Florida Fish and Wildlife Conservation Commission und 1987 vom U.S. Fish & Wildlife Service als bedrohte Art eingestuft. Die Bestände der Westküste Floridas werden genau beobachtet und untersucht. Dazu werden die Tiere farbig beringt, so dass die Individuen mit dem Fernglas identifiziert werden können. Der Lebensraum wird geschützt oder wiederhergestellt.
Die Erhebung in den Rang einer Art erfolgte im Jahr 1995.[1] Diese Entscheidung wurde durch Knochenfunde aus dem späten Pleistozän[2] sowie durch molekulargenetische und ökologische Befunde[3] bestätigt.
Der Florida-Buschhäher (Aphelocoma coerulescens) ist eine Singvogelart aus der Familie der Rabenvögel, die nur in Florida vorkommt.
The Florida scrub jay (Aphelocoma coerulescens[A]) is one of the species of scrub jay native to North America. It is the only species of bird endemic to the U.S. state of Florida and one of only 15 species endemic to the continental United States.[4] Because of this, it is keenly sought by birders. It is known to have been present in Florida as a distinct species for at least 2 million years,[5] and is possibly derived from the ancestors of Woodhouse's scrub jay.[6]
It measures 23 to 28 cm (9.1 to 11.0 in) in length, and weighs from 66 to 92 g (2.3 to 3.2 oz), with an average 80.2 g (2.83 oz). The wingspan of the jay is 33–36 cm (13–14 in).[7][8] It has a strong black bill, blue head and nape without a crest, a whitish forehead and supercilium, blue bib, blue wings, grayish underparts, gray back, long blue tail, black legs and feet.
The Florida scrub jay is found only in Florida scrub habitat, an ecosystem that exists only in central Florida and in limited areas along the Atlantic coast, and is characterized by nutrient-poor soil, occasional drought, and frequent wildfires. Because of its being isolated from the mainland as an island ("Orange Island") 34 to 28 million years ago [9] and somewhat harsh weather pattern, this habitat in isolation evolved to host not only the Florida scrub jay endemic only to Florida, but also a small assortment of very ancient specific plants, including sand pine, sand live oak, myrtle oak, Chapman's oak, sandhill oak, Florida rosemary[10] and various other hardy plants such as eastern prickly pear.[11]
Florida scrub jays are omnivorous and eat a wide variety of acorns, seeds, peanuts, insects, tree frogs, turtles, snakes, lizards, and young mice. They have also been occasionally observed to eat other birds' eggs or nestlings, but this occurs rarely.[12] They routinely cache thousands of acorns a year, burying them just beneath the surface. The acorns are typically buried in the fall and consumed during the winter and spring. Acorns that are forgotten or missed may germinate, making the Florida Scrub-Jay an effective agent for the dispersal of a variety of oak trees.
The Florida scrub jay may exhibit coordinated cooperative hunting, as seen in one case where a mated pair of the birds were observed attacking a black racer together in southcentral Florida. The snake may have been too large for one jay to kill it alone, and the pair ultimately succeeded in killing the reptile. Cooperated hunting like this is rarely documented in passerines.[13]
Scrub jays may also take silverware and other shiny objects in a manner similar to the American crow.
Florida scrub jays are one of the few cooperative breeding birds in North America. Fledglings remain in their parents' habitat for several years and help to rear young, watch for predators (such as short-tailed hawks or Accipiters), and defend territory against neighboring Florida scrub jay family groups. These families can range in size from 2 to 8.
After about 2 to 3 years, fledglings leave the group to form mating pairs of their own. Mating season ranges from March to June. Clutches usually contain about 3 to 4 eggs which are incubated in about 17 days. Fledging occurs in about 16 to 19 days. Fledglings can be distinguished from the adult birds due to the coloration of the feathers on their head, which are brown instead of blue. The brown feathers on the juvenile's head are slowly replaced by blue feathers as the bird matures into adulthood.
Scrub habitat has dwindled considerably in the past several decades as Florida has continued to develop. Wildfire suppression also leads to the natural succession of large oaks and trees which changes the habitat. In recent years, environmental groups within the state have made a strong effort at preserving Florida's remaining scrub through controlled burns and even clearing out areas of large trees to increase the size of a scrub habitat. Because scrub habitat is typically "well-drained sites with low nutrient levels and periodic fires," the species is vulnerable to climate change.[14] Oscar Scherer State Park near Sarasota has one of the larger habitats under state management.
The Florida scrub jay was officially listed as a threatened state species by Florida Fish and Wildlife Conservation Commission in 1975 and it was listed as a threatened federal species by the United States Fish and Wildlife Service in 1987.
According to Partners in Flight, there were estimated to be 4000 individuals left in the wild.[15] Despite the protections, the Florida scrub jay is still thought to be on the decline. Studies done in Brevard County, once the county with the greatest population of scrub jays, has noted declines of some 33% since the 1993 census alone.
Another attempt to conserve the bird is an ongoing campaign to name the Florida scrub jay as the new state bird of Florida. The main argument for changing the state bird is that the current state bird (viz. the northern mockingbird) is the state bird of several other states, while the scrub jay is exclusive to Florida.
In recent years there has been some debate about whether or not the Florida scrub jay should be officially listed as an Endangered Species because of the loss of homes. However, environmentalists hope that current conservation efforts should help the species population to at least stabilize.
On the other hand, the IUCN classifies this species as vulnerable to extinction.[1] In 2004, the population was declining and no more than 10 subpopulations were known. Both the number of adult birds as well as amount and quality of habitat were in decline, and local subpopulations were in danger of disappearing altogether. About 8000 mature birds were believed to exist—with no more than 1000 in any one subpopulation—and population numbers had dropped by about 10% over the last decade or so.
A long-term and ongoing study of the Florida scrub jay has been taking place at the Archbold Biological Station at Lake Placid.
The Florida scrub jay was featured in episode 11, season 3 of the Showtime television series Penn & Teller: Bullshit!.
An inquisitive and intelligent species, the most striking attribute of the Florida scrub jay's behavior is its remarkable tameness.[16] As such, scrub jays willingly take food from human hands.
Unfortunately, this tameness is dangerous to the well-being of the species.[17] Florida scrub jays that are fed by humans will reproduce earlier in the year than those that are not. However, fledgling scrub jays feed primarily on caterpillars present in the late spring and summer; if they hatch too early in the year when the caterpillars are not available, this can lead to their malnutrition or starvation.
Another potential danger of feeding Florida scrub jays occurs when people feed them near a road, as one major cause of death for scrub jays in urban areas is collision with vehicles.[18] Since humans build subdivisions, railroads, and highways on the highest and driest ground, where Florida scrub jays like to live, this removal of habitats, along with the introduction of pets, especially cats not on a leash, has devastated scrub jay populations. In the last 100 years, 90% of the bird's population has been lost.[19]
Two adults at Lyonia Preserve
Adult
Brown-colored head of a juvenile
Juvenile beginning to develop blue coloration on its head
Juvenile at Juniper Prairie in Ocala National Forest
{{cite journal}}: Cite journal requires |journal= (help) The Florida scrub jay (Aphelocoma coerulescens) is one of the species of scrub jay native to North America. It is the only species of bird endemic to the U.S. state of Florida and one of only 15 species endemic to the continental United States. Because of this, it is keenly sought by birders. It is known to have been present in Florida as a distinct species for at least 2 million years, and is possibly derived from the ancestors of Woodhouse's scrub jay.
La Florida makisgarolo (Aphelocoma coerulescens [1]) estas unu de la specioj de makisgaroloj indiĝena de Nordameriko. Ĝi estas la ununura specio de birdo endemiisma de la usona ŝtato de Florido. Pro tio ĝi estas ege serĉata de birdumantoj kiuj veturas tra la kamparo por observi tiun unikan specion. Oni scias ke loĝis en Florido kiel rekonebla distinga specio ekde almenaŭ maoj (Emslie, 1996 [2] ); eble ĝi devenas al la prauloj de la Makisgarolo de Woodhouse, internaj formoj de Okcidenta makisgarolo (Rice et al. 2003 [3]).
Ĝi estas 28 cm longa kaj pezas 75-85 g. Ĝ havas fortan nigran bekon, bluajn kapon kaj nukon sen kresto, blankecajn frunton kaj superokulon, bluan nuancon en brusto, bluajn flugilojn, grizecajn subajn partojn, grizan dorson, longan bluan voston, nigrajn gambojn kaj piedojn.
Tiu nearktisa specio estas scivolema kaj inteligenta kaj la plej rimarkinda atributo de la Florida makisgarolo estas ĝia rimarkinda malsovaĝeco. Floridaj makisgaroloj apenaŭ montras timon de homoj kaj eĉ prenas arakidojn el homaj manoj kaj lipoj, sed estas kontraŭleĝa manĝigi la Floridan makisgarolon[4]. Ĝi estas malprofita al ĝia sano kaj eĉ al la ĝenerala survivo de la specio: Floridaj makisgaroloj kiuj estas ofte manĝigataj de homoj reproduktiĝas pli frue en la jaro ol tiuj kiuj ne estas manĝigataj, draste malpliiganta la survivan indicon de la idaro.[5]. La idoj de makisgaroloj manĝas ĉefe raŭpojn kiuj estas en malfrua printempo kaj somero; sekve se la makisgarooloj reproduktiĝas tro frue en la jaro, la raŭpoj ne estas disponeblaj, kio kaŭzas misnutradon aŭ mortomalsategon de la idoj.
Alia eventuala danĝero manĝigi Floridajn makisgarolojn okazas kiam homoj manĝigas ilin ĉe ŝoseoj, ĉar unue el la ĉefaj kaŭzoj de morto en urbaj areoj estas surveturado[6].
La Florida makisgarolo troviĝas nur en la ekoregiono de la Floridaj sablopinaroj, ekosistemo ekzistanta nur en centra Florido. Ĝi karakteras pro sia malriĉa grundo, eventualaj sekecoj kaj oftaj incendioj. Pro tia malfavora klimato ĝi loĝas ĉe malgranda vario de tre specifaj plantoj, inklude sablopinoj, sablokverkoj, mirtokverko, kverko de Chapman, makiskverko kaj aliaj variaj fortaj plantoj kiel kaktoj.
Floridaj makisgaroloj estas ĉiomanĝantaj kaj manĝas ampleksan varion de glanoj, semoj, ternuksoj, insektoj, arboranoj, testudoj, serpentoj, lacertoj kaj etajn musojn. Foje eĉ oni observis la Floridan makisgarolon rabantajn aliajn birdojn el ties ovoj aŭ idoj, sed tio rare okazas[7]. Ili rutine kaŝas milojn de glanoj ĉiujare, enterigante ilin ĝuste sub la sabla surfaco. Ili estas kutime enterigitaj aŭtune kaj konsumitaj dumvintre kaj printempe. La netrovataj glanoj ĝermas kio igas la Floridan makisgarolon ĉefa disiganto de vario de kverkoj.
Floridaj makisgaroloj ankaŭ ŝtelas metalaĵojn kaj aliajn brilajn objektojn simile al la Larĝbeka korvo.
Ankaŭ Floridaj makisgaroloj estas unu el la malmultaj birdospecioj kiuj ĝuas la sistemon de la kooperativa reproduktado en Nordameriko. Junuloj de Floridaj makisgaroloj restas en la habitato de siaj gepatroj dum kelkaj jaroj kaj helpas zorgi la idojn, defendas el predantoj kaj defendas la teritorion kontraŭ najbaraj familigrupoj de Florida makisgarolo. Tiuj familioj povas grandi je 2 al 8.
Post ĉirkaŭ 2 al 3 jaroj, junuloj forlasas la grupon por formi paron per si mem. Pariĝanta sezono estas el marto al junio. Ovodemetado kutime estas de ĉirkaŭ 3 al 4 ovoj kiuj estas kovataj dum ĉirkaŭ 18 tagoj. Elnestiĝo okazas post ĉirkaŭ 16 al 19 tagoj. Junuloj distingiĝas el plenkreskuloj pro la koloro de plumoj en sia kapo, kiuj estas brunaj anstataŭ bluaj. La brunaj plumoj de la kapo de junulo estas malrapide anstataŭita de bluaj plumoj dum la birdo maturiĝas al plenkreskeco.
La makisa vivejo draste malpliiĝis dum la pasintaj jardekoj dum Florido pludisvolviĝis. Forigo pro incendioj kaŭzas la naturan ŝanĝon de grandaj kverkoj kaj arboj kio ŝanĝas ankaŭ la habitaton. En ĵusaj jaroj konservistaj grupoj de la ŝtato baraktis por konservi la restan makison de Florido pere de kontrolitaj incendioj kaj eĉ klarigado de areoj de grandaj arboj por pligrandigi la amplekson de la makisa habitato.
La Florida makisgarolo estis oficiale listita kiel minacata ŝtata specio de la Florida Natura Komitato en 1975 kaj estis listita kiel minacata federa specio de la Usona Natura Servo en 1987.
En 1993 oni ĉirkaŭkalkulis 4,000 reproduktantajn parojn en naturo. Spite la protekto la Florida makisgarolo estas ankoraŭ malpliiĝanta. Studoj de Kantono Brevard kiu iam estis la florida kantono kie loĝis la plej multnombraj Floridaj makisgaroloj notis malpliiĝon de ĉirkaŭ 33 % ekde la censo de 1993.
Alia klopodo por konservi tiun birdon estas kampanjo por elekti la Floridan makisgarolon kiel la nova ŝtata birdo de Florido. Alia kialo por ŝanĝi la ŝtatan birdon estas ke la nuna birdo (la Norda mimedo) estas la ŝtata birdo de kelkaj aliaj usonaj ŝtatoj dum nur la Florida makisgarolo estas ekskluziva de Florido.
Oni ĵus debatas pri la konveno ke la Florida makisgarolo estu oficiale listita kiel Endanĝerita Specio pro perdo de habitato. Tamen konservistoj esperas ke nunaj konservaj klopodoj helpu la stabilon de la specia populacio.
Aliflanke la IUCN klasigas tiun specion kiel vundebla al formorto VU B1ab(i,ii,iii,iv,v); C1+2a(i) (BirdLife International 2004). Tio signifas ke en 2004 la populacio estis malpliiĝanta kaj oni konis ne pli da 10 subpopulacioj. Kaj la nombro de plenkreskuloj kaj la kvanto kaj kvalito de vivejoj estis malpliiĝantaj kaj lokaj subpopulacioj estis en danĝero de malapero kune. Oni supozas, ke ekzistas ĉirkaŭ 8000 plenkreskuloj – kun ne pli da 1000 en ĉiu ajn subpopulacio -, kaj la nombroj de populacioj falis je ĉirkaŭ 10 % rilate la lasta jardeko.
Du plenkreskuloj de Florida makisgarolo ĉe Lyonia Preserve
Plenkreskulo de Florida makisgarolo
Brunkolora kapo de junulo de Florida makisgarolo
Junulo de Florida makisgarolo ekmontranta la bluan koloron en sia kapo
La Florida makisgarolo (Aphelocoma coerulescens ) estas unu de la specioj de makisgaroloj indiĝena de Nordameriko. Ĝi estas la ununura specio de birdo endemiisma de la usona ŝtato de Florido. Pro tio ĝi estas ege serĉata de birdumantoj kiuj veturas tra la kamparo por observi tiun unikan specion. Oni scias ke loĝis en Florido kiel rekonebla distinga specio ekde almenaŭ maoj (Emslie, 1996 ); eble ĝi devenas al la prauloj de la Makisgarolo de Woodhouse, internaj formoj de Okcidenta makisgarolo (Rice et al. 2003 ).
Ĝi estas 28 cm longa kaj pezas 75-85 g. Ĝ havas fortan nigran bekon, bluajn kapon kaj nukon sen kresto, blankecajn frunton kaj superokulon, bluan nuancon en brusto, bluajn flugilojn, grizecajn subajn partojn, grizan dorson, longan bluan voston, nigrajn gambojn kaj piedojn.
La chara floridana (Aphelocoma coerulescens),[3] conocida también como chara pecho rayado o urraca de los matorrales,[4] es una especie de ave paseriforme de la familia Corvidae. Es la única especie de ave endémica del estado de Florida y una de las 15 especies endémicas de los Estados Unidos.[5] Debido a esto es muy buscada por los observadores de aves que viajan desde todo el país para observar esta especie. Se sabe que han estado presentes en la Florida como una especie común reconocible distinta por al menos 2 millones de años,[6] posiblemente se deriva del Aphelocoma californica.[7]
Mide de entre 23 a 28 cm de longitud y pesa de 66 a 92 g, con un promedio de 80,2 g. La envergadura de la es 33 a 36 cm.[8][9] La cabeza la nuca y las alas son azules, la frente blanquecina, las partes inferiores grisáceas y la espalda gris, la cola es larga y de color azul. Las patas y el pico son negros.
Es originario de Estados Unidos, encontrándose solo en el estado de Florida. Su hábitat natural son los breñales de Florida, un ecosistema que existe sólo en el centro de Florida y se caracteriza por los suelos pobres en nutrientes, sequías ocasionales y los frecuentes incendios forestales.
En épocas de cría se han observado hasta seis ayudantes en el nido de una pareja. Estos "ayudantes", que suelen ser machos adultos hijos de la pareja reproductora, están preparados desde un punto de vista fisiológico para tener descendencia, pero invierten su tiempo y energía en alimentar a sus hermanos y en defender el territorio de la pareja reproductora (sus padres). Aunque los ayudantes de cría obtienen beneficios en términos de eficacia biológica indirecta por el hecho de ayudar a sus padres, estos beneficios no son tan importantes como los que obtendrían si tuvieran su propia descendencia. Sin embargo, el análisis de la densidad poblacional y de la disponibilidad de territorios para nidificar, indica que, a menos que un macho tenga un rango de dominancia elevado, no podrá hacerse con un territorio de nidificación ni defenderlo contra sus coespecíficos. Solamente los ayudantes de cría que ocupan los rango más elevados dejan de ser ayudantes y obtienen un territorio cuando fallece un vecino o uno de sus padres.[10]
La chara floridana (Aphelocoma coerulescens), conocida también como chara pecho rayado o urraca de los matorrales, es una especie de ave paseriforme de la familia Corvidae. Es la única especie de ave endémica del estado de Florida y una de las 15 especies endémicas de los Estados Unidos. Debido a esto es muy buscada por los observadores de aves que viajan desde todo el país para observar esta especie. Se sabe que han estado presentes en la Florida como una especie común reconocible distinta por al menos 2 millones de años, posiblemente se deriva del Aphelocoma californica.
Aphelocoma coerulescens Aphelocoma generoko animalia da. Hegaztien barruko Corvidae familian sailkatua dago.
Aphelocoma coerulescens Aphelocoma generoko animalia da. Hegaztien barruko Corvidae familian sailkatua dago.
Floridanpensasnärhi (Aphelocoma coerulescens)[2] on varisten heimoon kuuluva varpuslintu.
Floridanpensasnärhi on 27–31 cm pitkä. Vanhoilla yksilöillä on siniset siivet, pyrstö ja pää. Selkä on harmaa ja vatsapuoli vaalea. Päässä on valkea silmäkulmanjuova ja musta silmänympärys ja poskilaikku. Nokka ja jalat ovat mustat. Nuoret yksilöt ovat muuten samanlaisia, mutta niiden päälaki on ruskeanharmaa sinisen sijaan.[3]
Floridanpensasnärheä tavataan kotoperäisenä Yhdysvaltain Floridassa. Lajin kanta on vähentynyt 1900-luvun puolivälistä lähtien ja lajin esiintymisalueet ovat sirpaloituneet. Lajin kokonaiskannaksi on arvioitu 6 000–9 000 yksilöä ja laji on luokiteltu vaarantuneeksi.[1]
Floridanpensasnärhi elää pensasalueilla. Laji on riippuvainen tulipaloista ja palanut alue on lajille optimaalinen 5–15 vuoden päästä tulipalosta.[1] Se ei yleensä pesi metsäisillä alueilla, mutta voi elää myös esikaupunkialueilla.[4]
Floridanpensasnärhi pesii maalis–toukokuussa. Laji voi pesiä kahdesti kesän aikana, mutta se on harvinaista.[1]
Floridanpensasnärhi käyttää ravinnokseen niveljalkaisia, tammenterhoja ja pieniä selkärankaisia.[1]
Floridanpensasnärhi (Aphelocoma coerulescens) on varisten heimoon kuuluva varpuslintu.
Aphelocoma coerulescens
Le Geai à gorge blanche (Aphelocoma coerulescens) est une espèce de passereaux de la famille des Corvidae.
C'est le seul oiseau endémique à la Floride.
Aphelocoma coerulescens
Le Geai à gorge blanche (Aphelocoma coerulescens) est une espèce de passereaux de la famille des Corvidae.
La ghiandaia della Florida (Aphelocoma coerulescens (Bosc, 1795)) è un uccello passeriforme appartenente alla famiglia Corvidae[2].
Il nome scientifico della specie, coerulescens, deriva dal latino (sebbene tale vocabolo, anche nella sua variante caerulescens, non sia mai stato trovato in scritti latini) e significa "tendente al ceruleo", in riferimento alla livrea di questi uccelli.
Misura 26 cm di lunghezza, per 66-92 g di peso[3]: a parità d'età, le femmine sono leggermente più piccole rispetto ai maschi[3].
Si tratta di uccelli dall'aspetto massiccio, muniti di grossa testa squadrata e appiattita, becco conico e massiccio dalla punta lievemente adunca, ali arrotondate e digitate, forti zampe e lunga coda (quasi la metà del totale) dall'estremità squadrata.
Il piumaggio si presenta di colore azzurro-bluastro su vertice, nuca, lati del collo, spalle, codione, coda, remiganti e copritrici: dai lati del becco all'area temporale è presente una mascherina di colore blu scuro che abbraccia pure le guance, sormontata da una sopracciglio biancastro, che si congiunge al biancastro della fronte.
La gola è di colore bianco sporco, delimitato inferiormente da una banda azzurra: il dorso, le ali, il petto, il ventre e i fianchi sono di colore grigio topo, con sfumature azzurre soprattutto dorsalmente, mentre il sottocoda è di colore biancastro.
Il becco e le zampe sono di colore nero, mentre gli occhi sono di colore bruno scuro.
La ghiandaia della Florida è un uccello dalle abitudini di vita diurne, che vive in gruppi a base familiare, formati da una coppia riproduttiva coi figli di alcune delle covate precedenti. Ciascun gruppo delimita un proprio territorio di 5-10 ettari[4], che provvede a difendere mediante un membro che rimane di vedetta da un punto elevato, avvertendo gli altri membri mediante rauchi richiami d'allarme.
All'interno di uno stormo vige una gerarchia che vede dominare i maschi riproduttivi, seguiti da quelli non riproduttivi e dalle femmine (anche in questo caso con dominanza degli esemplari riproduttivi su quelli non riproduttivi)[4]: alla morte del maschio dominante, il suo posto nelle gerarchie viene ereditato dal più anziano dei maschi non riproduttivi[4].
Le ghiandaie della Florida sono uccelli molto loquaci, che comunicano mediante una varietà di richiami pigolanti di diversa durata ed intensità: in caso di interazione aggressiva, l'animale (in particolar modo le femmine) è solito annuire con la testa durante l'emissione dei richiami[3].
La ghiandaia della Florida è un uccello onnivoro ed opportunista, la cui alimentazione si basa su ciò che è disponibile al momento. Questi uccelli si cibano di un ampio range di cibi, sia di origine vegetale che animale: fra i cibi vegetali consumati vi sono ghiande, frutta, bacche e granaglie, mentre fra quelli di origine animale vi sono grossi insetti, larve, topolini, piccoli rettili (fra cui anche serpenti, che vengono predati in coppia[5]) e anfibi.
Similmente agli altri corvidi, le ghiandaie della Florida depredano i nidi degli altri uccelli per cibarsi di uova e nidiacei[5]: sebbene questi animali solo raramente attuino questo comportamento, non è invece infrequente che durante il periodo riproduttivo dei gruppi di ghiandaie della Florida saccheggino i nidi di coppie di altri gruppi, con alcuni esemplari che attirano i genitori lontano dal nido mentre altri distruggono la nidiata[5][6].
Le ghiandaie della Florida sono inoltre assidue frequentatrici delle mangiatoie situate nei giardini, ricavando il cibo anche dai rifiuti.
Come molti corvidi, questi uccelli sono soliti sotterrare il cibo in eccesso in buchi del terreno durante i mesi estivi, per poi poterlo conservare durante il periodo invernale.
Si tratta di uccelli monogami, le cui coppie rimangono unite per la vita.
La stagione riproduttiva comincia in febbraio (anche prima in contesti urbani[3]), con le coppie riproduttrici che si isolano temporaneamente per il corteggiamento (discreto e consistente in richiami e postura eretta da parte del maschio) e l'accoppiamento: ambedue i sessi in seguito rientrano nello stormo d'appartenenza per dare inizio alla nidificazione.
Il nido viene costruito dai due partner a 1-2 m dal suolo, in un cespuglio: esso presenta forma a coppa, è meno voluminoso rispetto a quanto osservabile nelle altre ghiandaie di boscaglia (18-20 cm di diametro[4]), con la parte esterna edificata con rametti e fibre vegetali e quella interna foderata di materiale più soffice.
All'interno del nido vengono deposte 2-5 uova di colore verdino, con screziature irregolari brunastre: esse vengono covate dalla sola femmina (col maschio che si occupa di nutrirla durante l'incubazione, ed assieme agli altri membri non riproduttivi dello stormo provvede a proteggerla da eventuali intrusi o predatori) per 16-18 giorni, al termine dei quali schiudono pulli ciechi e quasi completamente implumi.
I nidiacei vengono accuditi e imbeccati dalla sola femmina (a sua volta imbeccata dal maschio) per i primi giorni di vita, utilizzando quasi esclusivamente cibo di origine animale: in seguito, anche il maschio collabora attivamente alla loro alimentazione, e con lui fra i 2 e gli 8 aiutanti. Questi ultimi (in genere figli della coppia riproduttiva di covate precedenti, non riprodottisi), pur essendo generalmente già in grado di riprodursi, preferiscono aiutare la coppia riproduttiva, per aumentare in futuro le proprie possibilità di riprodursi con successo: durante l'opera di aiuto alla riproduzione, i livelli di testosterone degli animali calano[7].
I piccoli divengono in grado d'involarsi attorno alle tre settimane di vita: nonostante ciò, essi continuano a rimanere presso il nido natio ancora per altre tre settimane, ed anche dopo continuano a seguire i genitori nei loro spostamenti, chiedendo loro (sebbene sempre più sporadicamente) l'imbeccata, ancora per 10 settimane.
I maschi tendono a rimanere nel territorio natio, divenendo nelle stagioni successive aiutanti nella riproduzione dei genitori: le femmine, invece, una volta indipendenti tendono a disperdersi, entrando a far parte di altri stormi.
La speranza di vita della ghiandaia della Florida in natura è di circa 5 anni, mentre in cattività questi uccelli raggiungono gli 11 anni di vita[4].
Come intuibile dal nome comune, la ghiandaia della Florida è endemica della penisola della Florida, della quale popola in maniera piuttosto discontinua un areale compreso grossomodo fra le contee di Flagler, Marion e Citrus a nord e le contee di Collier, Glades e Palm Beach a sud.
Questi animali sono stanziali nel loro areale di residenza, compiendo spostamenti che spaziano al massimo di un raggio di 17 (per i maschi)-38 (per le femmine) km dal luogo di nascita[3].
Questi uccelli sono perfettamente adattati alla vita nell'ambiente secco e sabbioso del cosiddetto "Florida scrub", caratterizzato da suolo povero e da frequente siccità ed incendi.
L'habitat d'elezione di questi uccelli è rappresentato dalle aree di foresta secondaria a predominanza di querce, con presenza di ampie radure sabbiose a copertura cespugliosa: questi uccelli colonizzano inoltre senza problemi le aree urbane e suburbane, mentre tendono ad evitare quelle troppo densamente alberate e le pinete[3].
La ghiandaia della Florida (Aphelocoma coerulescens (Bosc, 1795)) è un uccello passeriforme appartenente alla famiglia Corvidae.
Aphelocoma coerulescens est species avis generis aphelocomae et familiae corvidarum. Habitat species Americae Septentrionali.
Species est 23 ad 28 centimetra longitudine, a 66 ad 92 grammata pondere cum valore medio 80.2 grammatum, et alarum passarum distantia est 33 ad 36 centimetra.
Haec stipula ad avem spectat. Amplifica, si potes! Aphelocoma coerulescens est species avis generis aphelocomae et familiae corvidarum. Habitat species Americae Septentrionali.
Species est 23 ad 28 centimetra longitudine, a 66 ad 92 grammata pondere cum valore medio 80.2 grammatum, et alarum passarum distantia est 33 ad 36 centimetra.
Floridas sīlis jeb Floridas krūmu sīlis (Aphelocoma coerulescens) ir vārnu dzimtas (Corvidae) putns, kas ir visretāk sastopamā suga krūmu sīļu ģintī.[1] Ģeogrāfisko variāciju nav.[2]
Floridas sīlis ir sastopams tikai Ziemeļamerikā, un tas ir endēms Floridas pussalai ASV. Tā ir vienīgā endēmā putnu suga Floridā. Floridas sīlis dzīvo šajā reģionā vismaz jau 2 miljonus gadu. Viens no Floridas sīļa populācijas apdraudējumiem ir sīļa spēja ātri pierast pie cilvēka un cilvēku vēlmes tos piebarot. Krūmu sīlis labprāt barojas no cilvēka rokas, bet tas savukārt noved pie tā, ka piebarotie sīļi agrāk pavasarī pārojas un sāk agrāk ligzdot. Mazos putnēnus Floridas sīlis baro ar tauriņu kāpuriem, un, ja putnēni ir izšķīlušies pārāk agri pavasarī, tie aiziet bojā vai cieš no bada.[3]
Floridas sīlis ir vidēja auguma vārnu dzimtas putns, tā ķermeņa garums ir apmēram 28 cm, svars 75—85 g. Tēviņi ir nedaudz lielāki nekā mātītes, bet apspalvojums abiem dzimumiem ir vienāds.[1] Tas ir pelēks ar zilu galvu, spārniem un asti. Kakls mugurpusē ir zils, bet pakakle ir pelēka. Knābis un kājas pelēkas.
Floridas sīlis ir sastopams centrālajā Floridas daļā, kuras nabadzīgajā augsnēaugsne| aug gandrīz tikai krūmi, videi ir raksturīgs sausums un reizēm reģionu piemeklē ugunsgrēki.[1] Skarbajos apstākļos augu dažādība ir neliela, raksturīgākie koki un krūmi ir Floridas smilšu priede (Pinus clausa),[4] Čapmana ozols (Quercus chapmanii), miršu ozols (Quercus myrtifolia), Floridas rozmarīns (Ceratiola ericoides) un indiāņu vīģe (Opuntia humifusa).[5]
Floridas sīlis ir visēdājs, tas barojas ar zīlēm, sēklām, zemesriekstiem, kukaiņiem, koku vardēm, bruņurupučiem, čūskām, ķirzakām un pelēm, kā arī pie izdevības tas izēd citiem putniem olas un putnēnus, tomēr tas notiek ļoti reti. Katru gadu krūmu sīlis savāc tūkstošiem zīļu un tās noslēpj smiltīs. Ar tām sīlis barojas ziemā un pavasarī. Ne visas zīles tiek atrastas, tādēļ Floridas sīlis ir galvenais ozolu stādītājs Floridā.
Floridas sīlis veido pāri uz mūžu. Katru gadu tas būvē jaunu ligzdu. Tā ir vīta no zariņiem un palmu šķiedrām. Ligzda tiek būvēta kādā zemā krūmā apmēram 1 metra augstumā no zemes.[1] Floridas sīlim mazuļu audzināšanā liela nozīme ir paplašinātai ģimenei. Tā sastāv no dominējošā pāra un iepriekšējo gadu bērniem, kas palīdz vecākiem izbarot jaunos putnēnus. Bars ne tikai baro mazuļus, tas arī sargā teritoriju pret ienaidniekiem un citām Floridas sīļu ģimenēm. Jaunie sīļi paliek kopā ar vecākiem vairākus gadus, ģimeni pametot pēc 2—3 gadiem. Barā dzīvo 2—8 pieauguši putni. Kamēr Floridas sīlim nav paplašināta ģimene, tas izbaro krietni mazāk putnēnus.[1]
Riests Floridas sīļiem sākas martā un turpinās līdz jūnijam. Dējumā ir 3—4 olas, inkubācijas periods ilgst 18 dienas. Apspalvojums izaug pēc 16—19 dienām. Jaunos putnus no pieaugušajiem putniem var atšķirt pēc to apspalvojuma uz galvas. Tas ir pelēkbrūns nevis zils, kā tas ir raksturīgs pieaugušajiem krūmu sīļiem. Pelēkbrūnās spalvas lēnām nomainās pret zilajām spalvām.
Floridas sīlis jeb Floridas krūmu sīlis (Aphelocoma coerulescens) ir vārnu dzimtas (Corvidae) putns, kas ir visretāk sastopamā suga krūmu sīļu ģintī. Ģeogrāfisko variāciju nav.
De Struikgaai (Aphelocoma coerulescens) is een zangvogel uit de familie van de kraaiachtigen (Corvidae) die in de Noord-Amerikaanse staat Florida leeft. Het is tevens de enige endemische vogelsoort van Florida. Daarom is hij erg populair bij vogelspotters, die van overal in Amerika naar Florida reizen om hem te kunnen zien. De struikgaai is ongeveer 28 cm lang en weegt 75 tot 85 gram. Hij heeft een zwarte bek, een blauwachtig hoofd (voorhoofd is witachtig) en blauwe vleugels. Zijn rug is grijs en zijn poten zijn zwart. De struikgaai heeft ook een lange, blauwe staart.
Het is een nieuwsgierige en relatief intelligente vogelsoort en zijn opmerkelijkste eigenschap is dat hij in het geheel niet mensenschuw is. De vogels nemen gewillig voedsel uit menselijke hand. Dit gedrag is echter ook meteen een bedreiging voor het algemeen welzijn van de soort. Struikgaaien die regelmatig door mensen gevoed worden, zullen sneller in het jaar jongen krijgen dan diegenen die niet gevoed worden, en pas jongen krijgen in het late voorjaar wanneer er voldoende rupsen zijn. Op deze manier worden vogels sterk afhankelijk van deze mensen, en dreigen de jongen van de honger te sterven wanneer de mensen niet voldoende voedsel ter beschikking stellen. Regelmatig gevoederde vogels verliezen op termijn namelijk ook het instinct om zelf actief naar voedsel te zoeken. Een andere bedreiging voor deze vogels, tevens door mensen veroorzaakt, is het drukke verkeer in Florida. Omdat de vogels plaatsen opzoeken waar veel mensen aanwezig zijn, komen ze regelmatig op drukke verkeerswegen terecht. Velen sterven hierdoor onder wagens.
De struikgaai komt enkel voor in Florida, een staat die gekenmerkt wordt door regelmatige droogteperiodes, voedingsarme bodems, frequente bosbranden en een complex weersysteem (met jaarlijks orkaanseizoen). Struikgaaien zijn mede hierdoor echte opportunisten en eten dus vrijwel alles, van eikels, zaden en pinda’s tot insecten, kikkers, schildpadden, slangen, hagedissen en muizen. Daarnaast zijn het ook eierdieven. In de herfst begraven ze massaal eikels op verschillende plaatsen in de bodem, die ze dan in de winter en het voorjaar consumeren. Eikels die niet teruggevonden worden, kunnen ontkiemen en zich op termijn tot nieuwe bomen ontwikkelen. Op die manier draagt deze vogel een cruciaal steentje bij in het diversificatieproces van het Floridaanse landschap.
Wanneer jonge struikgaaien het nest verlaten, blijven ze nog enkele jaren in de buurt van de ouders vertoeven. Op deze manier ontstaan er familiegroepen, die soms tot acht leden kunnen bevatten. De oudere vogels zullen in deze jaren nog steeds in bepaalde mate hun jongen beschermen, onder meer tegen roofdieren en naburige struikgaaifamilies. Na twee tot drie jaar verlaten de jonge dieren deze groep om hun eigen familiegroep te gaan stichten. Het broedseizoen loopt van maart tot juni. De vogels leggen drie tot vier eieren die na ongeveer 18 dagen uitkomen. Juvenielen hebben een ander verenkleed dan de ouderdieren, ze zijn namelijk eerder bruinachtig van kleur en niet blauw.
Bronnen, noten en/of referentiesDe Struikgaai (Aphelocoma coerulescens) is een zangvogel uit de familie van de kraaiachtigen (Corvidae) die in de Noord-Amerikaanse staat Florida leeft. Het is tevens de enige endemische vogelsoort van Florida. Daarom is hij erg populair bij vogelspotters, die van overal in Amerika naar Florida reizen om hem te kunnen zien. De struikgaai is ongeveer 28 cm lang en weegt 75 tot 85 gram. Hij heeft een zwarte bek, een blauwachtig hoofd (voorhoofd is witachtig) en blauwe vleugels. Zijn rug is grijs en zijn poten zijn zwart. De struikgaai heeft ook een lange, blauwe staart.
Het is een nieuwsgierige en relatief intelligente vogelsoort en zijn opmerkelijkste eigenschap is dat hij in het geheel niet mensenschuw is. De vogels nemen gewillig voedsel uit menselijke hand. Dit gedrag is echter ook meteen een bedreiging voor het algemeen welzijn van de soort. Struikgaaien die regelmatig door mensen gevoed worden, zullen sneller in het jaar jongen krijgen dan diegenen die niet gevoed worden, en pas jongen krijgen in het late voorjaar wanneer er voldoende rupsen zijn. Op deze manier worden vogels sterk afhankelijk van deze mensen, en dreigen de jongen van de honger te sterven wanneer de mensen niet voldoende voedsel ter beschikking stellen. Regelmatig gevoederde vogels verliezen op termijn namelijk ook het instinct om zelf actief naar voedsel te zoeken. Een andere bedreiging voor deze vogels, tevens door mensen veroorzaakt, is het drukke verkeer in Florida. Omdat de vogels plaatsen opzoeken waar veel mensen aanwezig zijn, komen ze regelmatig op drukke verkeerswegen terecht. Velen sterven hierdoor onder wagens.
Multimedia w Wikimedia Commons Modrowronka zaroślowa (Aphelocoma coerulescens) – gatunek ptaka z rodziny krukowatych (Corvidae).
Długość ciała 28-33 cm. Smukła sójka bez czubka; z wierzchu granatowoniebieska, z szarobrązowym grzbietem. Pokrywy uszne szare. Gardło i góra piersi szare w delikatne niebieskie kreski z niebieskoszarą półobrożą na piersi o różnej szerokości (zależnie od podgatunku). Pokrywy podogonowe białawe do niebieskich.
Zakrzewione tereny Florydy i południowo-wschodniej części USA[2].
Modrowronka zaroślowa (Aphelocoma coerulescens) – gatunek ptaka z rodziny krukowatych (Corvidae).
Floridasnårskrika[2] (Aphelocoma coerulescens) är en fågel i familjen kråkfåglar inom ordningen tättingar.[3] Fågeln förekommer lokalt i ett brett öst-västligt band över Florida.[3] IUCN kategoriserar arten som sårbar.[1]
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Wikimedia Commons har media som rör floridasnårskrika.
Wikispecies har information om Aphelocoma coerulescens.
Floridasnårskrika (Aphelocoma coerulescens) är en fågel i familjen kråkfåglar inom ordningen tättingar. Fågeln förekommer lokalt i ett brett öst-västligt band över Florida. IUCN kategoriserar arten som sårbar.
Aphelocoma coerulescens là một loài chim trong họ Corvidae.[3]
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Aphelocoma coerulescens (Bosc, 1795)
Ареал
Голубая кустарниковая сойка[1] (лат. Aphelocoma coerulescens) — птица семейства врановых, обитающая только во Флориде.
Голубая кустарниковая сойка длиной 28 см. Затылок, верхние кроющие крыльев и хвост ярко-синие. Спина, нижняя сторона и лоб серые. Ниже зоба тёмная лента. Кроющие уха, а также нижняя сторона крыльев и хвоста, радужная оболочка глаз, клюв и ноги тёмные.
Ареал ограничен районами Флориды, поросшими кустарником. Предпочитаемое жизненное пространство характеризуется засухами и частыми пожарами. В этой среде произрастает небольшой ассортимент конкретных растений (сосна песчаная, цератиола, дуб), плоды которых, помимо древесных лягушек, змей и насекомых, составляют основной рацион питания этих птиц.
Популяция вида сократилась в XX веке из-за уничтожения жизненного пространства примерно на 90 %. В 1975 году Комиссия по сохранению рыбных ресурсов и дикой природы Флориды[en] и в 1987 году Служба охраны рыбных ресурсов и диких животных США классифицировали вид как находящийся под угрозой. Популяции западного побережья Флориды точно наблюдаются и исследуются. Для этого животных окольцовывают разным цветом, так чтобы их можно было идентифицировать, глядя в бинокль. Жизненное пространство охраняется или восстанавливается.
Присуждение статуса вида произошло в 1995 году[2]. Это решение было подтверждено находками костей из позднего плейстоцена[3], а также молекулярно-генетическим и экологическим заключением[4].
Голубая кустарниковая сойка (лат. Aphelocoma coerulescens) — птица семейства врановых, обитающая только во Флориде.
丛鸦（学名：Aphelocoma coerulescens），是鸦科丛鸦属的一种，为美国的特有种。全球活动范围约为6,900平方千米。该物种的保护状况被评为易危。
丛鸦的平均体重约为77.2克。栖息地为亚热带或热带的（低地）干燥疏灌丛。
丛鸦（学名：Aphelocoma coerulescens），是鸦科丛鸦属的一种，为美国的特有种。全球活动范围约为6,900平方千米。该物种的保护状况被评为易危。
丛鸦的平均体重约为77.2克。栖息地为亚热带或热带的（低地）干燥疏灌丛。
保全状況評価 VULNERABLE
分類 界 : 動物界 Animalia 門 : 脊索動物門 Chordata 亜門 : 脊椎動物亜門 Vertebrata 綱 : 鳥綱 Aves 目 : スズメ目 Passeriformes 科 : カラス科 Corvidae 属 : アメリカカケス属フロリダカケス （学名：Aphelocoma coerulescens）は、スズメ目カラス科に分類される鳥類の一種。
この項目は、鳥類に関連した書きかけの項目です。この項目を加筆・訂正などしてくださる協力者を求めています（ポータル鳥類 - PJ鳥類）。 
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