occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Breeding
Regularity: Regularly occurring
Type of Residency: Breeding
Global Range: BREEDING: southwestern British Columbia, western Washington, central Oregon, southwestern Idaho, northern Utah, southwestern Wyoming, northwestern and central Colorado, south in mountains to Arizona, eastern and southern New Mexico, northern Baja California, and northeastern Sonora, Mexico (AOU 1983, Guzy and Lowther 1997). Centers of abundance based on BBS data are in eastern Utah, southeastern Arizona, the Sierra Nevada, northwestern California, western Oregon, western Washington, and southwestern British Columbia (Sauer et al. 1997). NON-BREEDING: primarily in Baja California Sur and Pacific Slope and interior of Snora, Durango, Zacatecas, and Coahuila south to central Oaxaca. In small numbers in California and along Gulf Coast of U.S. (Guzy and Lowther 1997).
Length: 13 cm
Weight: 9 grams
Comments: BREEDING: Breeds in a variety of semi-arid woodlands; dry, open forests; mixed, moist forests; brushlands; chaparral. Especially uses conifers, live oaks, and mixed pinyon-juniper woodlands (Dunn and Garrett 1997). Inhabits juniper-pinyon-oak scrub on slopes, foothills, and canyons, where (in Wyoming) it is strongly associated with the presence of pinyon pine and high seedling/sapling density and understory height (Pavlacky and Anderson 2001). Also inhabits fir forests and edges of clearings. Nests in trees or shrubs 1-10 meters above ground, sometimes up to 15 meters (Harrison 1978; M. Guzy, pers. comm.). An early observer noted that the species likes well-scattered conifers; prefers high and dry places; and does not mind marsh or river nearby if ground beneath the nest is dry (Bowles 1902).
Generally uses younger age classes in northwest forests. In Douglas-fir forests in western Washington and Oregon, Meslow and Wright (1975) found the species nesting in shrub-sapling (7-15 years old), older second growth (41-120 years) and mature (> 120 years) successional communities, and using but not nesting in 16-40 year-old second growth. In Oregon Coast Range Douglas-fir forests, Carey et al. (1991) found highest densities in young stands (40-72 years; 9.06 birds per 40 hectares two-year average) in contrast to mature (80-120 years; 2.37 birds per 40 hectares two-year average) and old-growth stands (200-250 years; 3.04 birds per 40 hectares two-year average). Young stands typically had high densities of small-diameter trees (mean 269.7 stems per hectare of trees 10-19 centimeter dbh) and low densities of large trees over 50 centimeter dbh; also few large snags and low vertical foliage density. Similarly, in Douglas-fir forests of the Washington Cascades, were detected more frequently in young stands (55-80 years; mean 0.19 birds per visit) than in mature (95-190 years; 0.02 birds per visit) or old-growth stands (300-730 years; 0.06 birds per visit; Manuwal 1991). Young stands contained the highest mean densities (70 trees per hectares) of live trees less than 50 centimeter dbh and high densities (70 per hectare) of small snags less than 19 centimeter dbh. Huff and Raley (1991) also detected birds more often in young stands than in mature and old-growth stands in the Oregon Coast Ranges and Southern Washington Cascades, but in the Oregon Cascades they found little difference between stand age classes although the species was detected on a slightly greater percentage of old-growth stands.
On Vancouver Island, British Columbia, most often found in 50- to 60-year-old stands of mixed forests; an important elementis relatively open but brushy undergrowth (Campbell et al. 2001).
In southern Idaho, uses low ridges covered with open junipers (Burleigh 1972). In California, inhabits dry, open woodlands and brushy understories of foothills and mountains; breeds in ponderosa pine (PINUS PONDEROSA), valley-foothill hardwood-conifer, montane hardwood and pinyon-juniper habitats, and prefers oak woodland or pinyon-juniper mixed with chaparral or brushy understories (USDA Forest Service 1994). In northwestern Colorado pinyon-juniper habitat, prefers late-successional woodlands and occurs in similar woodland habitat to Plumbeous Vireo (VIREO PLUMBEOUS) and Dusky Flycatcher (EMPIDONAX OBERHOLSERI; Sedgwick 1987). In the Northwest, will use stands of regenerating deciduous trees and conifers in old clearcuts and burns (Dunn and Garrett 1997). In northern Arizona pinyon-juniper, observed to use and nest in juniper slightly more than other bird species (Balda 1969). In Mexico and northern Central America, breeds in semi-arid pine-oak and juniper woodland (Howell and Webb 1995). Breeds from 3,000 to 7,000 feet in the Sierra, up to 9,500 feet in White Mountains, California, but much lower in the Northwest (Dunn and Garrett 1997).
NON-BREEDING: In winter, uses arid mountain woodlands, including pine-oak. May use riparian habitats as travel corridors (USDA Forest Service 1994). In California, uses oaks and riparian willows and cottonwoods; in southwestern U.S., bottomland cottonwoods, willows, mesquite, and sycamores (Dunn and Garrett 1997). In Mexico and northern Central America, winters in arid to semi-humid oak and pine-oak forest and scrub (Howell and Webb 1995). In western Mexico, Hutto (1992) classified this species as a two-zone generalist that primarily uses tropical deciduous forest and thorn forest, and only 5 percent of observations were in pine-oak forest.
Habitat and Ecology
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.
Winters north of the Isthmus; from California lowlands and southern Arizona through western and central Mexico, from southern Baja, southern Sonora and Coahuila south to Oaxaca (Dunn and Garrett 1997).
Comments: Feeds mainly on insects (moths, butterflies, beetles, ants, etc.); may also eat leaf galls and a few spiders. Forages among leaves in bushes and trees. May forage high in trees or lower in trees and bushes. In southwestern Oregon and northwestern California use oak trees in spring for foraging on small green caterpillars (Bowles 1902).
Seen singly or in pairs; may be seen in small groups while migrating.
Life History and Behavior
Clutch size is three to five (usually four). Incubation is done by female. Young are tended by both parents (Harrison 1978).
Molecular Biology and Genetics
Barcode data: Dendroica nigrescens
There are 7 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Dendroica nigrescens
Public Records: 7
Specimens with Barcodes: 9
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N4B - Apparently Secure
Rounded National Status Rank: N5B - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
IUCN Red List Assessment
Red List Category
Red List Criteria
Comments: May have a potentially high risk of local extinction due to a low frequency of occurrence, low abundance, long-distance migration, and loss of late-successional coniferous forests (Lehmkuhl and Ruggiero 1991). TIMBER HARVEST: Impacts of the broad range of timber harvest activities are mostly unknown. GRAZING: Grazing impacts largely unknown. Grazing in riparian vegetation along Sacramento River valley may threaten wintering populations in California (USDA Forest Service 1994), presumably by damaging or removing shrubs and saplings. PREDATION: Accipiters prey on adults; jays, crows and snakes prey on eggs and young (Guzy and Lowther 1997). BROOD PARASITISM: Considered a rare brown-headed cowbird (MOLOTHRUS ATER) host (Ehrlich et al. 1988), but little studied. Total of 20 records known; parasitism rates in very limited samples in California, Arizona, and New Mexico were 10 percent to 20 percent (see Guzy and Lowther 1997). In white Mountains, California, two nests were observed that had nest layers built over a cowbird egg, but no other antiparasitic responses have been recorded (Guzy and Lowther 1997).
Restoration Potential: This species uses a wide variety of woodlands and appears to respond positively to early successional stages of forest regeneration, so restoration potential would likely be high in a landscape of sustainable forest harvest or natural disturbance regimes. Sustaining riparian woodlands and chaparral habitats may be important to this warbler during migration and wintering. However much more detailed information is needed on the species biology to be conclusive about positive measures for restoration.
Preserve Selection and Design Considerations: May be area sensitive. Found to be positively associated with increasing stand area in Douglas-fir forests fragmented by timber harvest, however, no significant associations found with other measures of fragmentation (Rosenberg and Raphael 1986).
Management Requirements: Effects of management activities and disturbance are largely unstudied. Terborgh (1989) notes use of disturbed oak-woodland habitats on wintering grounds, but does not define type or extent of disturbance.
GRAZING: Effects of grazing activities are generally unknown. In pinyon-juniper, overstory removal to create pasture would be detrimental (Sedgwick 1987).
TIMBER HARVEST: Species is absent when forest overstory is removed. However, in an Engelmann spruce-subalpine fir forest, remained in interconnected forest remnants surrounding clearcuts four years after logging (8.30 singing males per 100 hectare; minimum width of residual stands was 413 +/- 59 meters) and occurred in similar densities to unlogged continuous forest (9.96 males per 100 hectares; Wetmore et al. 1985). The impacts of woodland fragmentation on productivity and survivorship are apparently unstudied. In pinyon-juniper habitats, tree removal may affect habitat use, as this warbler shows a preference for more mature trees in this habitat (Sedgwick 1987).
In northwestern Douglas-fir forests, however, shows a preference for younger stands, and densities are likely to be higher in young regenerating stands than in mature stands (Raphael et al. 1988, Carey et al. 1991, Huff and Raley 1991, Manuwal 1991). In the Oregon Coast Ranges, mean abundance was greater (P = 0.03) in unthinned stands than in stands commercially thinned five to fifteen years previous, where approximately 20 to 30 percent of the number of trees per hectare had been removed (Hagar et al. 1996). In even-age Douglas fir forests regenerating from clearcutting, Marcot (1985) found that mean densities were highest in shrub/sapling plots than in pole timber and medium sawtimber plots.
FIRE: Very little information available on relationship to burns. In a seasonal study of non-breeding bird abundances in ponderosa pine (PINUS PONDEROSA) forests on the Prescott National Forest, Arizona, Blake (1982) found the species restricted to unburned sites in fall and spring migration seasons.
Management Research Needs: Need detailed studies of response to habitat changes, including productivity and survivorship; monitoring of long-term changes in density in response to habitat alterations and succession; study of landscape and cumulative effects of habitat changes; rates of brood parasitism and behavioral response to parasitism. Information on migration and winter habitat use and ecology also needed.
Biological Research Needs: Nearly all aspects of the biology are poorly known. An excellent species for amateur and professional biologists to make significant contributions, especially as this warbler is relatively common and widespread and occupies a variety of woodland habitats. Studies are needed of behavior, breeding biology, wintering ecology, geographic variation in song, population dynamics, site fidelity, dispersal and migration.
Relevance to Humans and Ecosystems
Stewardship Overview: Has been little studied despite being widespread and relatively common in appropriate woodland habitats. Apparently prefers younger-aged successional stands of forest in the northwest, and in the short term, populations may be expected to increase in the region as the extensive harvest units of the 1970s and 1980s regenerate (Raphael et al. 1988, Spies et al. 1994). In pinyon-juniper habitats, however, shows a preference for mature trees and may be impacted by tree removal. Riparian areas, oak-woodlands, and chaparral are also important habitats. However, in western Douglas-fir forests are found in greatest abundance in young successional stands (Raphael et al. 1988, Carey et al. 1991, Huff and Raley 1991, Manuwal 1991). Much more information is needed to understand the species landscape relationships and ecology, particularly in response to habitat changes.
Species Impact: An insectivore that may be beneficial in reducing insect pests.
Black-throated Gray Warbler
The Black-throated Gray Warbler (Setophaga nigrescens) is a songbird of the New World warbler family. It is 13 cm (5 in) long and has black, gray, and white plumage. It breeds in western North America from British Columbia to New Mexico, and winters in Mexico and the southwestern United States. Common in its forest habitats, it does not seem to be seriously threatened by human activities, unlike many migratory warblers.
The Black-throated Gray Warbler has mostly black, gray, and white plumage, which is soft, lacking gloss. With its striping and the small yellow spot between its eye and bill, it is a distinctive bird. The sexes differ slightly, both having gray upperparts with black streaks, and white underparts with black streaks on the flanks. The adult male is striped on its head, with a black crown, throat, and stripe below the eye, and white around its chin and above its eye. The adult female has more dingy plumage on its head, with a white throat and dark gray cheeks. The most similar birds to the Black-throated Gray Warbler are the Black-and-white and Blackpoll Warblers, which although black have entirely different patterns.
It is typically 13 cm (5 in) long, weighing 8.4 g (0.29 oz). Wing lengths are 5.6–6.9 cm (2.2–2.7 in), tail lengths 4.7–5.5 cm (1.9–2.2 in), bill lengths 8.4–9.6 cm (3.3–3.8 in), and tarsus lengths 1.66–1.88 cm (0.65–0.74 in), with females slightly smaller than males.
This bird gives a sharp tup or thick call, like that of Townsend's Warbler but flat and unmusical, as well as a high see flight call. The male's song is a series of buzzy notes, with the earlier notes doubled and the next to last note high. This song has three variations, including a quiet "soft song" given by the males while following females gathering material for a nest.
The Black-throated Gray Warbler was first described by John Kirk Townsend from a specimen collected near today's Portland, Oregon. It was known to the Chinook inhabitants of the northwest coast, who called it Ah Kah a qual. Townsend described the species as Sylvia nigrescens, placing it with the other New World warblers and the unrelated Old World warblers in the genus Sylvia. It is now placed in the genus Dendroica, along with about thirty other species. Within this genus, it is part of a group with black throats and yellow face markings that includes the Hermit Warbler and Townsend's Warbler. Among these species, it is usually considered an early offshoot, but genetic studies suggest a close relation to Grace's Warbler.
Of these relatives, Townsend's Warbler and the Hermit Warbler overlap with the Black-throated Gray Warbler, but inhabit different habitats. While these two species hybridize commonly, records of hybridization with the Black-throated Gray Warbler are uncommon.
There are two subspecies, which are highly similar and of dubious validity. The nominate subspecies D. n. nigrescens occurs on the Pacific coastal region from British Columbia to northern California, while D. n. halseii, described by Giraud in 1841, occupies the remainder of its range. D. n. halseii birds are slightly larger and more gray in their upperparts.
Distribution and habitat
The Black-throated Gray Warbler breeds in western North America, its range extending from southwestern British Columbia along the Pacific coast, and east to New Mexico and southern Montana. It winters mostly in Mexico, from southern Baja California to Oaxaca state. It has spread into parts of Wyoming and Montana only recently, as Juniperus osteosperma has expanded its range due to a warming climate. Vagrants have been recorded across eastern North America. It breeds in open coniferous and mixed forest with a brushy understory, in dry open oak forests, and in chaparral and other scrubland. It is particularly associated with pinyon pines, junipers, and oaks. It migrates to the south late in the fall, returning north in mid-spring. While migrating, it forages in any woodland or scrub it passes through. In its wintering grounds, it occurs in dry woodland and tall scrub. Though its status is not well known, it does not appear to be seriously threatened by habitat destruction or other human activities, unlike many migratory warblers. It is a fairly common bird, among the most common in some localities. Because of its commonality, it is assessed as Least Concern on the IUCN Red List.
The Black-throated Gray Warbler is usually approachable, and can easily be observed while foraging. Despite this, it is poorly known, especially in its breeding behavior, of which Birds of North America said "almost no information is available". It forages, often in flocks with other species. It feeds on insects gleaned on low branches, especially caterpillars.
The nest is usually placed on a horizontal tree branch or in a shrub, a few metres above the ground. The nest is an open cup constructed of grass stalks and other fibres, and lined with feathers and hair. The female lays 3–5 pinkish eggs with brown dots from May to July. Incubation and fledgeing periods are not recorded. It has been recorded giving a distraction display, pretending to be injured to distract predators from its nest. Both parents feed the young, though the female may do so more frequently.
- BirdLife International (2012). "Dendroica nigrescens". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Coues 1878, pp. 263–267
- Curson, Quinn & Beadle 1994, pp. 126–128
- Audubon & Macgillivray 1849, pp. 57–59
- Sibley 2000, p. 437
- Morrison, Michael L.; and Hardy, John William (1983). "Vocalizations of the Black-throated Gray Warbler" (PDF). The Wilson Bulletin 95 (4): 643–647.
- Guzy, Michael J., and Lowther, Peter E. (1997). "Black-throated Gray Warbler (Dendroica nigrescens)". In Poole, A. The Birds of North America Online. Retrieved 29 April 2010.
- American Ornithologists' Union 1983, pp. 539–551
- Rabosky, Daniel L.; and Lovette, Irby J. (2008). "Density-dependent diversification in North American wood warblers". Proceedings of the Royal Society B 275 (1649): 2363–71. doi:10.1098/rspb.2008.0630. PMC 2603228. PMID 18611849.
- Rohwer, Sievert (1994). "Two New Hybrid Dendroica Warblers and New Methodology for Inferring Parental Species". The Auk 111 (2): 441. doi:10.2307/4088607.
- Rohwer, Sievert; Wood, Christopher; and Bermingham, Eldredge (2000). "A New Hybrid Warbler (Dendroica nigrescens × D. occidentalis) and Diagnosis of Similar D. townsendi × D. occidentalis Recombinants" (PDF). The Condor 102 (3): 713–718. doi:10.1650/0010-5422(2000)102[0713:ANHWDN]2.0.CO;2. JSTOR 1369809.
- "Dendroica nigrescens". Integrated Taxonomic Information System. Retrieved 29 April 2010.
- Hendricks, Paul (2004). "First nesting record of black-throated gray warbler (Dendroica nigrescens) for Montana" (PDF). Western North American Naturalist 64 (4): 548–540.
- Garret, Kimball L.; Dunning, John B., Jr. (2001). "Wood-Warblers". In Elphick, Chris; Dunning, John B. Jr.; Sibley, David Allen. The Sibley Guide to Bird Life and Behavior. New York: Alfred A. Knopf. pp. 492–509. ISBN 978-1-4000-4386-6.
- Remsen, J. V., Jr.; Cardiff, Stephen (1979). "First records of the race scotti of the Rufous-crowned Sparrow in California". Western Birds 10 (1): 45–46.
- Sprunt, Alexander, Jr. (1979). "Black-throated Gray Warbler". In Sprunt, Alexander, Jr.; and Griscom, Ludlow. The Warblers of North America (Revised and updated ed.). Doubleday. ISBN 0-385-12353-1.
- Finley 1908, p. 127
- Wheelock 1912, pp. 401–404
- Barlow, C. (1899). "The Nesting Haunts of the Black-throated Gray Warbler". Bulletin of the Cooper Ornithological Club 1 (5): 96–97. doi:10.2307/1360756.
- Grinnell & Storer 1924, pp. 529–531
- Finley, William L. (1923). "Black-throated Gray Warbler". In Pearson, T. Gilbert. Birds of America 3.
- American Ornithologists' Union (1983). Check-list of North American Birds (7th ed.). Washington, D.C.: American Ornithologists' Union. ISBN 1-891276-00-X.
- Audubon, John James; Macgillivray, William (1849). Ornithological biography, or An account of the habits of the birds of the United States of America: accompanied by descriptions of the objects represented in the work entitled The birds of America, and interspersed with delineations of American scenery and manners V. Edinburgh: Judah Dobson, A. Black.
- Coues, Eliot (1878). Birds of the Colorado Valley: A Repository of Scientific and Popular Information Concerning North American Ornithology, Part First, Passeres to Laniidae. United States Geological and Geographical Survey of the Territories, Miscellaneous Publications—No. 11. Washington: Government Printing Office.
- Curson, Jon; Quinn, David; Beadle, David (1994). Warblers of the Americas: an Identification Guide. Boston: Houghton Mifflin. ISBN 0-395-70998-9.
- Finley, William Lovell (1908). American Birds, Studied and Photographed from Life. New York: Charles Scribner's Sons.
- Grinnell, Joseph; Storer, Tracy Irwin (1924). Animal life in the Yosemite; an account of the mammals, birds, reptiles, and amphibians in a cross-section of the Sierra Nevada. University of California Press.
- Sibley, David Allen (2000). The Sibley Guide to Birds. New York: Alfred A. Knopf. ISBN 978-0-679-45122-8.
- Wheelock, Irene Grosvenor (1912). Birds of California: an Introduction to More Than Three Hundred Common Birds of the State and Adjacent Islands, with a Supplementary List of Rare Migrants, Accidental Visitants, and Hypothetical Subspecies. Chicago: A. Ac. McClure.
Names and Taxonomy
Comments: Phylogenetic analyses of sequences of mitochondrial and nuclear DNA (Lovette et al. 2010) indicate that all species formerly placed in Dendroica, one species formerly placed in Wilsonia (citrina), and two species formerly placed in Parula (americana and pitiayumi) form a clade with the single species traditionally placed in Setophaga (ruticilla). The generic name Setophaga has priority for this clade (AOU 2011).