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Overview

Brief Summary

Hylocichla mustelina

A medium-sized (8 inches) thrush, the Wood Thrush is most easily identified by its brown back, rusty-red head, and heavily spotted breast. Other field marks include pinkish legs, short tail, and thick, slightly curved bill. Male and female Wood Thrushes are similar to one another in all seasons. The Wood Thrush breeds across the eastern United States and southern Canada from New Brunswick and Nova Scotia south to northern Florida and west to North Dakota. In winter, this species migrates south to southern Mexico and Central America. Like many bird species wintering in the American tropics, the Wood Thrush crosses the Gulf of Mexico twice a year while on migration. Wood Thrushes primarily breed in deciduous forests with a tall canopy and open forest floor. In winter, this species inhabits humid tropical forests. Wood Thrushes mainly eat insects and other invertebrates during the breeding season, but may also eat fruits and berries during the winter. In appropriate habitat, it may be possible to see Wood Thrushes hopping along the forest floor while foraging for insect prey. More often, however, Wood Thrushes are identified by their song, an unmistakable series of flute-like notes repeated with numerous embellishments and alterations. Wood Thrushes are primarily active during the day, but, like many migratory songbirds, this species migrates at night.

Threat Status: Least concern

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Distribution

occurs (regularly, as a native taxon) in multiple nations

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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

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Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: southeastern North Dakota and central Minnesota across the northern U.S. and adjacent southern Canada to Nova Scotia; south to eastern Texas, the Gulf Coast, and northern Florida; and west to eastern South Dakota, central Nebraska, central Kansas, and eastern Oklahoma. Casual breeder to southern Manitoba, southwestern North Dakota, and central South Dakota (AOU 1983). NON-BREEDING: southern Texas south through eastern Mexico and Middle America to Panama and northwestern Colombia (AOU 1983).

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Geographic Range

The breeding range of wood thrushes (Hylocichla_mustelina) extends from southern Canada to northern Florida and from the Atlantic coast to the Missouri River and the eastern Great Plains. Wood thrushes spend winters in Mexico and Central America, mostly in the lowlands along the Atlantic and Pacific coasts.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

  • Roth, R., M. Johnson, T. Underwood. 1996. Wood thrush (*Hylochicla mustelina*). Pp. 1-28 in A Poole, F Gill, eds. The Birds of North America, Vol. 246. Philadelphia, PA: The Academy of Natural Sciences and Washington, D.C.: The American Ornithologists' Union.
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Range

Breeds e North America; winters s Texas to Panama.

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Geographic Range

The breeding range of wood thrushes (Hylocichla mustelina) extends from southern Canada to northern Florida and from the Atlantic coast to the Missouri River and the eastern Great Plains. Wood thrushes spend winters in Mexico and Central America, mostly in the lowlands along the Atlantic and Pacific coasts.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

  • Roth, R., M. Johnson, T. Underwood. 1996. Wood thrush (*Hylochicla mustelina*). Pp. 1-28 in A Poole, F Gill, eds. The Birds of North America, Vol. 246. Philadelphia, PA: The Academy of Natural Sciences and Washington, D.C.: The American Ornithologists' Union.
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Physical Description

Morphology

Physical Description

Wood thrushes are small songbirds. They are 19 to 21 cm long and weigh 40 to 50 g. They are cinnamon-brown on the top of their head and back of their neck. Their back, wings and tail are olive-brown. Their breast and belly are white with big dark brown spots. They have a dull white ring around their eye, a brown bill, and pink legs.

Male and female wood thrushes look very similar. Young wood thrushes look similar to adults, but they have spots on their back, neck and wings as well.

Range mass: 40 to 50 g.

Range length: 19 to 21 cm.

Sexual Dimorphism: sexes alike

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Physical Description

Wood thrushes are small songbirds, 19 to 21 cm long and weighing 40 to 50 g. They are warm cinnamon-brown on the crown and nape, with a slightly duller olive-brown on the back, wings and tail. The breast and belly are white with conspicuous large dark brown spots on the breast, sides and flanks. Wood thrushes have a dull white ring around their eye. Their bill is dark brown, and their legs are pinkish.

Male and female wood thrushes are similar in size and plumage. Juveniles look similar to adults, but have additional spots on their back, neck and wing coverts.

Wood thrushes can be easily confused with other similar-looking thrushes. They are distinguished by the rusty color on their head, and the white, rather than buffy, breast and belly.

Range mass: 40 to 50 g.

Range length: 19 to 21 cm.

Sexual Dimorphism: sexes alike

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Size

Length: 20 cm

Weight: 47 grams

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Diagnostic Description

Smaller than American Robin (TURDUS MIGRATORIUS) and plumper than the other brown thrushes (Gray-cheeked Thrush [CATHARUS MINIMUS], Bicknell's Thrush [CATHARUS BICKNELLI], Swainson's Thrush [CATHARUS USTULATUS], Hermit Thrush [CATHARUS GUTTATUS], and Veery [CATHARUS FUSCESCENS]). Distinguished by the deepening redness about the head and the larger, more numerous round spots on the breast. Nest is similar to that of robin but is smaller and invariably has leaves in foundation and rootlets instead of grass in lining. Eggs are smaller and generally more pointed at one end than are robin eggs; also slightly paler than robin eggs (Harrison 1975).

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Ecology

Habitat

Comments: BREEDING: deciduous or mixed forests with a dense tree canopy and a fairly well-developed deciduous understory, especially where moist (Bertin 1977, Roth 1987, Roth et al. 1996). Bottomlands and other rich hardwood forests are prime habitats. Also frequents pine forests with a deciduous understory and well-wooded residential areas (Hamel et al. 1982). Thickets and early successional woodland generally do not provide suitable habitat (Bertin 1977). Bertin (1977) found wood thrushes to require one or more trees at least 12 m tall, possibly for song perches, whereas Morse (1971) reported nesting in stands of young white pine with a canopy under 9 m in height. Nests usually are placed in a crotch or are saddled on a branch of a shrub, sapling, or large tree,

NON-BREEDING: In migration and winter, habitats include forest and woodland of various types from humid lowland to arid or humid montane forest, also scrub and thickets; primarily undisturbed to moderately disturbed wet primary forest; may wander into riparian forest and various stages of second growth (Rappole et al. 1989, Winker et al. 1990). Were recorded exclusively in forest in Atlantic lowlands of Costa Rica (Hagan and Johnston 1992). Winker et al. (1990) studied within-forest preferences of birds wintering in southern Veracruz and found that areas with gaps were preferred in this lowland rainforest; areas with heavy ground cover were also favored.

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Habitat and Ecology

Systems
  • Terrestrial
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Wood thrushes live in deciduous and mixed forests. They prefer older forests with shrubs in the understory. They also like to have trees taller than 16 m, moist soil and leaf litter on the ground. Wood thrushes also like areas where there is running water. They can breed in small patches of forest, but large areas of forest keep them safer and allow them to raise more chicks.

Wood thrushes spend the winter in the understory of old tropical forests. However, they may also be found along the edges of forests, and in younger forests.

Range elevation: 1325 (high) m.

Habitat Regions: temperate ; tropical ; terrestrial

Terrestrial Biomes: forest

  • Bertin, R. 1977. Breeding habitats of the wood thrush and veery. The Condor, 79: 303-311.
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The breeding range of wood thrushes is composed of deciduous and mixed forests. They prefer late-successional, upland mesic forests with a moderately-dense shrub layer. Other important elements of wood thrush breeding habitat include trees taller than 16 m, a fairly open forest floor, moist soil, and leaf litter. Bertin (1977) found that wood thrushes favor areas with running water, moist ground and high understory cover. Substrate moisture is more important than canopy cover or access to running water. Wood thrushes can breed in habitat patches as small as 1 acre, but those that breed in larger tracts of forest experience lower predation and lower nest parasitism, leading to higher reproductive success.

Wood thrushes winter primarily in the interior understory of tropical primary forests. However, they may also occur along forest edges and in second growth.

Range elevation: 1325 (high) m.

Habitat Regions: temperate ; tropical ; terrestrial

Terrestrial Biomes: forest

  • Bertin, R. 1977. Breeding habitats of the wood thrush and veery. The Condor, 79: 303-311.
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Migration

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.

Arrives in wintering areas in Middle America in October (Rappole et al. 1989); males first arrive in the southern U.S. in March-April (Terres 1980). Migrates through Costa Rica late September to mid-November and March-April (Stiles and Skutch 1989).

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Trophic Strategy

Comments: Eats insects and other invertebrates (e.g., snails), and small fruits; forages mainly on or near ground, sometimes in tree foliage (Terres 1980).

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Food Habits

Wood thrushes are omnivorous. They prefer soil invertebrates and larvae, but they will eat fruits in late summer, fall, and winter. Occasionally they feed on arboreal Insecta, Stylommatophora, and small Caudata. In late summer, wood thrushes begin eating fruits with a lot of fat in them. This helps them to store up energy for their fall migration

Wood thrushes feed mostly on the forest floor. They can be seen hopping around in leaf litter and on the ground under the forest canopy, gleaning insects and probing the soil with their bills. They use their bill to turn over leaves in search of prey.

Animal Foods: amphibians; insects; terrestrial non-insect arthropods; mollusks; terrestrial worms

Plant Foods: fruit

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Food Habits

Wood thrushes are omnivorous; they feed preferentially on soil invertebrates and larvae, but will eat fruits in late summer, fall, and late winter. Occasionally they feed on arboreal insects, snails, and small salamanders. During the post-breeding and pre-migration time, wood thrushes switch from insects to fruits with high lipid levels. During the summer, low fruit consumption and lipid reserves require the birds to feed continuously on insects in order to meet their daily metabolic needs.

Wood thrushes feed primarily on the forest floor. They can be observed hopping around in leaf litter and on semi-bare ground under the forest canopy, gleaning insects and probing the soil. They use their bill to turn over leaves to reveal prey. Fruits are swallowed whole.

Animal Foods: amphibians; insects; terrestrial non-insect arthropods; mollusks; terrestrial worms

Plant Foods: fruit

Primary Diet: omnivore

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Associations

Ecosystem Roles

Wood thrushes affect the populations of the insects and other animals they eat. They may help to disperse the seeds of the fruits they eat. They also provide food for their predators.

Ecosystem Impact: disperses seeds

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Predation

Eggs and chicks are vulnerable to predation by Tamias striatus, Procyon lotor, Cyanocitta cristata, Corvus brachyrhynchos, Elaphe obsoleta, Molothrus ater, Quiscalus quiscula, Blaucomys volans, Sciurus carolinensis, Mustela rixosa, Peromyscus leucopus, Felis silvestris, Bubo virginianus and Accipiter striatus. Adults are probably taken primarily by Falconiformes and Strigiformes.

When predators are nearby, adult wood thrushes become alert and responsive to sounds. When their nests or young are threatened, adults respond with agitated calls and chases, escalating into dives and strikes.

Known Predators:

  • eastern chipmunks (Tamias_striatus)
  • raccoons (Procyon_lotor)
  • blue jays (Cyanocitta_cristata)
  • American crows (Corvus_brachyrhynchos)
  • black rat snakes (Elaphe_obsoleta)
  • brown-headed cowbirds (Molothrus_ater)
  • common grackles (Quiscalus_quiscula)
  • southern flying squirrels (Glaucomys_volans)
  • eastern gray squirrels (Sciurus_carolinensis)
  • least weasels (Mustela_nivalis)
  • Peromyscus leucopus
  • Felis silvestris
  • Bubo virginianus
  • Accipiter striatus

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Ecosystem Roles

Wood thrushes affect the populations of the insects and other animals they eat. They may help to disperse the seeds of the fruits they eat. They also provide food for their predators.

Ecosystem Impact: disperses seeds

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Predation

Eggs and chicks are vulnerable to predation by chipmunks, raccoons, blue jays, American crows, black rat snakes, brown-headed cowbirds, common grackles, southern flying squirrels, gray squirrels, least weasels, white-footed mice, domestic cats, great horned owls and sharp-shinned hawks. Adults are probably taken primarily by hawks and owls.

When predators are nearby, adult wood thrushes become alert and responsive to sounds. When their nests or young are threatened, adults respond with agitated calls and chases, escalating into dives and strikes.

Known Predators:

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Known prey organisms

Hylocichla mustelina (wood thrush) preys on:
Diptera
Auchenorrhyncha
Sternorrhyncha
Lepidoptera
Coleoptera
Hymenoptera

Based on studies in:
USA: Illinois (Forest)

This list may not be complete but is based on published studies.
  • A. C. Twomey, The bird population of an elm-maple forest with special reference to aspection, territorialism, and coactions, Ecol. Monogr. 15(2):175-205, from p. 202 (1945).
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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

Comments: Many occurrences.

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Global Abundance

10,000 to >1,000,000 individuals

Comments: Certainly far more than 10,000 individuals.

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General Ecology

POPULATION DENSITY: Published information on densities from breeding bird censuses in the southeastern U.S. between 1947 and 1979 were summarized by Hamel et al (1982): mean (standard error) density is listed as 14.2 (1.0) pairs per 40 ha with a density range of 1-41 pairs per 40 ha. In bottomland hardwood forests along the Roanoke River in eastern North Carolina, R. Sallabanks (unpubl. data) found thrushes to be most abundant in wide patches of levee forest where an average 1.14 singing males were detected per unlimited radius 10-min point count. Holmes and Sherry (1988) reported a mean (standard error) abundance in Hubbard Brook Experimental Forest, New Hampshire, of 4.64 (2.83) adult birds per 10 ha over the period 1969-1986 over which time the population showed a highly significant decline at Hubbard Brook (a similar pattern to that reflected for the state of New Hampshire population by BBS data). Whitcomb et al.(1981) found 125 males per sq km in an area in Maryland.

TERRITORIES: Freemark and Merriam (1986) listed the territory size as less than 2 ha. In wintering areas in southern Veracruz, some individuals were territorial and highly sedentary, often remained within 150 m of capture point for entire winter; other birds wandered (Rappole et al. 1989, Winker et al. 1990). Some birds return to same wintering areas in successive years (Rappole et al. 1989).

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Life History and Behavior

Behavior

Communication and Perception

Wood thrushes communicate using song and body signals. Male wood thrushes sing a very unique song that sounds like a flute and ends in a trill. Female wood-thrushes do not sing. Wood thrushes also use calls, such as "bup, bup" or "tut, tut" to signal that they are agitated.

Communication Channels: visual ; acoustic

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Communication and Perception

Wood thrushes communicate using song and physical displays. Male wood thrushes sing a very unique song that ends in a trill. They are able to sing two notes at once, giving their songs an ethereal, flute-like quality. Female wood-thrushes are not known to sing. Wood thrushes also use calls, such as "bup, bup" or "tut, tut" to signal agitation.

Communication Channels: visual ; acoustic

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Life Expectancy

Lifespan/Longevity

The oldest known wood thrush lived to be at least 8 years and 11 months old. Most wood thrushes do not live to be that old.

Range lifespan

Status: wild:
8.9 (high) years.

Average lifespan

Status: wild:
107 months.

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Lifespan/Longevity

The oldest known wood thrush lived to be at least 8 years and 11 months old. Annual adult survival rates are estimated to be 70% for males and 75% for females.

Range lifespan

Status: wild:
8.9 (high) years.

Average lifespan

Status: wild:
107 months.

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Lifespan, longevity, and ageing

Maximum longevity: 8.9 years (wild)
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Reproduction

Nesting occurs in late spring and early summer. In Delaware, nesting peaks occurred in the last week of May and in the second week of July (Longcore and Jones 1969). Nest site selection and building is by the female alone; complete in about five days. No evidence birds ever use nest a second time. Clutch size is 2-5 (usually 3-4). Individual females typically produce two broods per year. Incubation, by female, lasts 12-14 days. Male usually guards nest when female absent. Young are tended by both parents, leave nest at 12-13 days. Pair remains together for second nesting (Harrison 1975). There is some evidence of occasional polygyny (Johnson et al. 1991).

In Delaware, of 142 "nesting attempts," 38% were successful and 58% of nests were destroyed by predators. The greatest nest success was associated with late season nests, spicebush and black gum vegetation, and with lower nest height (below 8.5 ft); 33% of eggs hatched, and 65% of hatched birds survived to leave the nest (Longcore and Jones 1969). In Maryland, Whitcomb et al. (1981) reported that thrushes produced two broods per year and had a reproductive success of 7.60. In Pennsylvania, nesting failure was caused by predation more than 95% of the time (Hoover 1992); 78% of nest depredation was attributed to small mammal/snake/avian nest predators and 22% to large mammal nest predators. Much work on reproductive success in wood thrushes has also been done by Hoover (1992) in relation to forest fragmentation.

Long-term population dynamics in a 15-ha woodlot were studied in Delaware by Roth and Johnson (1993). A sustained episode of reduced production per female and of an increased percentage of adults failing to produce any young coincided with a 4% annual decline in abundance between 1978 and 1987. When failure rate later dropped, return rate and abundance subsequently increased. Roth and Johnson (1993) concluded that a period of elevated, predation-caused failure prompted greater emigration by an ever-younger, less-site-faithful population.

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Wood thrushes are monogamous (one male mates with one female). Breeding pairs form in mid-April and early-May. They usually stay together for most of the summer, and often raise two broods together. Most wood thrushes find a new mate each year.

Mating System: monogamous

Male wood thrushes begin arriving in the spring a few days before the females. A few days after arriving, they set up territories and begin to sing to attract a mate. Once breeding pairs have formed, they begin searching for a nest site.

The female usually chooses the nest site and builds the nest. The nest is located in a tree or shrub, and is built of dead grasses, stems or leaves, and lined with mud. The female lays 2 to 4 eggs, and incubates them for about 13 days. When the chicks hatch, they are naked and helpless. The female broods the chicks for the first four days or so to keep them warm and protect them. Both parents feed the nestlings and remove their fecal sacs from the nest. The chicks leave the nest (called fledging) when they are 12 to 15 days old. The parents continue to feed them until they are about 21 to 31 days old.

Most breeding pairs try to raise two broods in one season. The first eggs are laid in mid-May, and the second clutch of eggs are laid in July. Wood thrushes begin breeding when they are about one year old.

Breeding interval: Wood thrushes breed once per year. They may raise one or two broods per breading season.

Breeding season: Wood thrushes breed between April and August.

Range eggs per season: 2 to 8.

Range time to hatching: 11 to 14 days.

Average time to hatching: 13 days.

Range fledging age: 12 to 15 days.

Range time to independence: 21 to 31 days.

Range age at sexual or reproductive maturity (female): 1 to 1 years.

Range age at sexual or reproductive maturity (male): 1 to 1 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Average eggs per season: 3.

The female usually chooses the nest site and builds the nest. The female also incubates the eggs and broods the chicks for the first four days after hatching. Both parents feed the chicks and remove fecal sacs from the nest.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Male); pre-hatching/birth (Protecting: Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female)

  • Roth, R., M. Johnson, T. Underwood. 1996. Wood thrush (*Hylochicla mustelina*). Pp. 1-28 in A Poole, F Gill, eds. The Birds of North America, Vol. 246. Philadelphia, PA: The Academy of Natural Sciences and Washington, D.C.: The American Ornithologists' Union.
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Wood thrushes are monogamous. Breeding pairs form in mid-April and early-May, and usually last for the duration of the breeding season (through several nesting attempts or two complete broods). Most wood thrushes find a new mate each year. Mate guarding and extra-pair copulation have not been documented in this species.

Mating System: monogamous

Male wood thrushes begin to sing at dawn and dusk a few days after their arrival at breeding grounds. Some males arrive on the breeding grounds several days before the earliest females to establish territories, while other males arrive at the same time as the females. Behaviors such as circular flights led by the female interspersed with perching together are characteristic of wood thrush pair formation and/or pre-copulatory behaviors.

The female typically chooses the nest site and constructs the nest. The nest is located in a tree or shrub, and is constructed of dead grasses, stems or leaves, and lined with mud. The female lays 2 to 4 eggs (usually 4 for first clutch, 3 for later clutches) at a rate of one per day. The eggs are incubated for 11 to 14 days (average 13 days) by the female only. The chicks are altricial at hatching; they are mostly naked with closed eyes. The female broods the chicks during the first four days after hatching. Both parents feed the nestlings and remove fecal sacs from the nest. The chicks fledge from the nest 12 to 15 days after hatching. The parents continue to feed them until they become independent and leave the parents' territory at 21 to 31 days old. These chicks will be able to begin breeding the next summer.

The majority of females lay their first eggs in mid-May, with older females laying sooner. Most pairs attempt to rear a second brood usually no later than late July, with the last young fledging around mid-August.

Breeding interval: Wood thrushes breed once per year. They may raise one or two broods per breading season.

Breeding season: Wood thrushes breed between April and August.

Range eggs per season: 2 to 8.

Range time to hatching: 11 to 14 days.

Average time to hatching: 13 days.

Range fledging age: 12 to 15 days.

Range time to independence: 21 to 31 days.

Range age at sexual or reproductive maturity (female): 1 to 1 years.

Range age at sexual or reproductive maturity (male): 1 to 1 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Average eggs per season: 3.

The female usually chooses the nest site and builds the nest. The female also incubates the eggs and broods the chicks for the first four days after hatching. Both parents feed the chicks and remove fecal sacs from the nest.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Male); pre-hatching/birth (Protecting: Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female)

  • Roth, R., M. Johnson, T. Underwood. 1996. Wood thrush (*Hylochicla mustelina*). Pp. 1-28 in A Poole, F Gill, eds. The Birds of North America, Vol. 246. Philadelphia, PA: The Academy of Natural Sciences and Washington, D.C.: The American Ornithologists' Union.
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Hylocichla mustelina

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 4 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.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNACTGCCCTGAGCCTCCTAATCCGAGCAGAACTAGGCCAGCCAGGCGCCTTACTAGGAGACGACCAAATTTACAATGTAGTNGTTACTGCCCATGCATTCGTAATAATTTTCTTCATAGTTATACCAATCATAATCGGGGGGTTTGGAAACTGATTAGTCCCCCTGATAATTGGAGCCCCAGACATAGCATTCCCCCGAATAAACAACATAAGCTTTTGACTTCTCCCCCCATCTTTTCTCCTCCTCCTAGCTTCATCCACAGTAGAAGCAGGAGCAGGGACAGGCTGAACCGTTTATCCTCCCCTAGCCGGCAACTTAGCACATGCAGGGGCTTCAGTAGACCTAGCTATCTTCTCCCTACACCTAGCTGGTATCTCCTCAATCCTAGGGGCTATCAACTTTATCACCACAGCAATCAACATAAAACCACCTGCCCTCTCACAATACCAAACCCCTCTATTCGTTTGATCTGTACTAATCACCGCAGTACTACTTCTCCTATCCCTCCCCGTACTTGCTGCAGGAATTACCATGCTCCTTACCGACCGCAACCTAAACACCACCTTCTTCGACCCAGCAGGAGGAGGAGACCCAGTACTATACCAACACCTCTTCTGATTTTTCGGCCACCCCGAAGTGTACATCCTCATCCTT
-- end --

Download FASTA File
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Statistics of barcoding coverage: Hylocichla mustelina

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 5
Specimens with Barcodes: 6
Species With Barcodes: 1
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Conservation

Conservation Status

National NatureServe Conservation Status

Canada

Rounded National Status Rank: N4B - Apparently Secure

United States

Rounded National Status Rank: N5B - Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

Reasons: Large range in eastern North America; many occurrences; decreasing population trend but still common in many areas; threatened by forest fragmentation and resulting increases in brood parasitism by cowbirds and nest predation.

Other Considerations: ALABAMA: Breeding Bird Survey data have shown that in the 22 years from 1966-1987, wood thrushes in Alabama have declined at an alarming rate of 33% per year (Reid and Droege 1989). Major threat is habitat loss and fragmentation due to conversion of natural forest to pine plantations; residential development, strip mining, and road construction are also contributing to habitat loss in Alabama (Bailey, pers. comm.). Historically the wood thrush was a common and well-established summer resident in Alabama (and apparently may even winter here on occasion). It frequents primarily the lower parts of low, moist, shaded hardwoods, but also occurs in mixed woods and rarely in pure pine stands (Imhof 1976). ARKANSAS: Birds are widely distributed during summer, but are more numerous on the Coastal Plain than elsewhere. In Arkansas, the nesting habitat of the wood thrush tends to have less ground cover, fewer shrubs, fewer small and large trees but more moderately sized trees, and greater canopy cover than the average condition throughout its summer range (James and Neal 1986). DELAWARE: Breeding throughout the state, the wood thrush population is stable, or possibly declining. Habitat fragmentation is the major threat; should populations become degraded, C. M. Heckscher (pers. comm.) suggests connecting forests, establishing canopy cover, native shrub understory, and maintaining soil moisture. Important predators in Delaware are Raccoons and blue jays. To sustain wood thrushes, forests should be at least 75-100 acres in size with 80% canopy cover (minimum), and have native understory shrubs. Roland Roth (University of Delaware) is an expert on the wood thrush in Delaware and elsewhere. ILLINOIS: The wood thrush is on the "Watch List" for this state, numbers of individuals are unknown, the state population is decreasing, and the range has not changed. Cowbird parasitism is by far the most significant threat to this species in Illinois (Kleen, pers. comm.). According to Graber et al (1971), the breeding distribution in Illinois is very poorly known, especially in any quantitative detail; most records seem to be in the northern part of the state. More recent information may now be more substantial. Indiana: wood thrushes breed throughout Indiana. Summer bird count data for 1985-1990 indicate the species to be in 100% of northern counties, 97% of central counties, 97% of southern counties, and 98% of counties statewide. Although a common summer resident today, it may have been more numerous 100 years ago. Observers have not recorded large numbers during migration; it may be a rare winter resident (Castrale and Martin, pers. comms.). KANSAS: Little seems to be known about the wood thrush in Kansas, which gives the bird a state rank of S3. The population trend is downward and the range is contacting from west to east. Currently, wood thrushes are distributed in roughly the eastern third of the state. Major threats here, as elsewhere, are habitat degradation (conversion to agriculture, lowered water tables in the west) and Cowbird parasitism. W. H. Busby (pers. comm.) speculated that loss of wintering habitat may be the biggest threat; the rate of decline of the wood thrush is much greater than would be predicted by factors in Kansas alone. MAINE: The wood thrush is not tracked in Maine and therefore little is known about numbers or status. L. Tudor (pers. comm.) suggests that forest fragmentation and herbicide reversion to spruce-fir forest are the major threats. Selective cutting to produce a mixed uneven-aged forest is suggested as an important factor to consider if designing a preserve around this species. Maine approaches the northern limit of the wood thrush's range which has apparently been expanding northward over the past few decades; wood thrushes are more common in the southern part of the state. MARYLAND: The wood thrush rank of S5 may soon be re-evaluated to S4 in Maryland because of widespread, regional decline. There are over 1,100 Breeding Bird Atlas records although how many element occurrences are protected is unknown. In Maryland, wood thrushes prefer swamps, floodplain forests, and moist upland deciduous forests containing an understory of small trees and shrubs (Davidson, pers. comm.). MICHIGAN: The wood thrush is an abundant summer resident of southern and middle Michigan although numbers have declined and the species is less abundant now than 20 years ago. Breeding Bird Survey data show a decline in Michigan averaging 5.2%/year since 1966 (Pinkowski 1991). MINNESOTA: On migration the wood thrush is uncommon in the southeastern quarter of the state and rare elsewhere in the spring. Breeds throughout the state except in the heavy coniferous forests adjacent to the Canadian border. Most common in the southeast from Hennepin County southward and eastward; to the north and west of this area the species is scarce (Green and Janssen 1975). NEBRASKA: Not tracked in Nebraska, the wood thrush is a common to uncommon spring and fall migrant in the eastern part of the state. A local summer resident in wooded eastern areas, extending west locally to Cherry, Lincoln, and Thomas County (Johnsgard 1980). NEW JERSEY: A common summer resident/breeder in northern and central New Jersey, and has been generally increasing in southern New Jersey (Dutko, pers. comm.). NEW YORK: This species is common in southeastern, central, and western New York state, uncommon to rare in more northern areas, and absent from the higher mountains. Breeding Bird Survey data suggest that wood thrush numbers have increased between 1965 and 1979, but trends since then are unknown (Schneider, pers. comm.). NORTH CAROLINA: The state population is in strong decline and in considerable trouble. The wood thrush is found statewide and in the mountains perhaps up to 4000 ft, but is replaced by the Veery in mid- and upper-levels (LeGrand, Jr., pers. comm.). OHIO: Common and widespread in Ohio, if the wood thrush were ranked it would be an S5 (i.e., this species is not tracked in this state). Contiguous canopy with good understory development (no deer) are recommended as being good for wood thrush promotion. Loss of habitat in western and central Ohio are offset by gains in eastern and southern Ohio (Rice, pers. comm.). PENNSYLVANIA: Center of abundance in Pennsylvania is now in the eastern part of the Allegheny High Plateau and the adjoining western Glaciated Low Plateau sections. Breeding Bird Survey data indicate a peak in numbers in the mid-1970's but numbers have declined since then to pre-peak levels (Barton, pers. comm.). RHODE ISLAND: Currently widespread throughout Rhode Island, absent from heavily urbanized areas and outer coastal regions where woodlands are lacking. Susceptible to habitat fragmentation, the wood thrush in Rhode Island could be declining, although there's no hard evidence (Enser, pers. comm.). SOUTH DAKOTA: Having a state rank of S2, there are only eight element occurrences for the wood thrush in South Dakota; there are, however, large habitat areas available despite the loss of the Missouri River riparian areas. Most element occurrences are on Corps of Engineers' property and "could" be protected (Newton Hills State Park). Distribution is primarily southeastern South Dakota along the Missouri River wherever habitat remains; there is one record for northeastern South Dakota. Cowbirds and loss of habitat are the major threats in South Dakota, as elsewhere (Backland, pers. comm.). VERMONT: Common throughout the state, the wood thrush is not tracked and little is known about population size, element occurrences, and/or range. From 23 annual Breeding Bird Survey routes between 1966 and 1989, there was a nonsignificant 1.1% annual decline; from 1980-1989, however, there was a significant 5.7% annual decline. Bottomland deciduous forests are preferred, but mixed coniferous-deciduous forests are also used at higher elevations. VIRGINIA: A major threat in this state is suburban and second home development in northern Virginia. Distributed throughout the state with a concentration of records in the far north (Mabey, pers. comm.). WEST VIRGINIA: Occurs throughout the state and undoubtedly breeds in every county. Wood Thrushes occur primarily in dense mature deciduous forest and are found in this forest even at the highest elevations. Also occur in the mixed spruce-northern hardwood forests, but are absent from the pure spruce forests (Hall 1983).

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2012

Assessor/s
BirdLife International

Reviewer/s
Butchart, S. & Symes, A.

Contributor/s

Justification
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
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Wood thrushes are becoming less common. This is probably because the forests that they breed in are being cut down, or divided up into smaller patches. Wood thrushes prefer large patches of forest over small patches. They are able to raise more chicks is large forests because predators are less common. They can also raise more chicks in large forests because nest parasites, such as Molothrus ater are less common.

Wood thrushes are protected under the U.S. Migratory Bird Act. There are about 14,000,000 wood thrushes in the world.

IUCN Red List of Threatened Species: least concern

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

  • Hoover, J., M. Brittingham. 1993. Regional variation in cowbird parasitism of wood thrushes. Wilson Bulletin, 105: 228-238.
  • Hoover, J., M. Brittingham, L. Goodrich. 1995. Effects of forest patch size on nestling success of wood thrushes. The Auk, 112: 146-155.
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Continent-wide wood thrush populations appear to have declined significantly over the past several decades. This decline can be attributed largely to habitat loss and habitat fragmentation. Wood thrushes are usually found in mature forests; nesting in residential areas and other disturbed sites is rare. They are significantly less abundant in fragmented areas bordered by roads and power lines compared to larger tracts of forest.

Brood parasitism by brown-headed cowbirds is more common in forested habitats with a high proportion of edge than in large tracts of forest. Brood parasitism leads to decreased reproductive success of wood thrushes. The rate of parasitism varies by region; rates are much higher in the Midwest than in the Northeast or Mid-Atlantic regions. Reproductive success is also affected by increased predation in smaller forest patches. A study conducted in Pennsylvania found that less than half (46%) of wood thrush nests were successful in forest patches less then 80 ha in size, while in large continuous forests, 86% of nests were successful. Rates of predation are higher in smaller forest patches with large edge areas, possibly because small patches cannot support large predators that regulate smaller nest predators and nest predators tend to be abundant in small patches, which they use for foraging.

Wood thrushes are protected under the U.S. Migratory Bird Act. There are about 14,000,000 wood thrushes throughout the geographic range.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

  • Hoover, J., M. Brittingham. 1993. Regional variation in cowbird parasitism of wood thrushes. Wilson Bulletin, 105: 228-238.
  • Hoover, J., M. Brittingham, L. Goodrich. 1995. Effects of forest patch size on nestling success of wood thrushes. The Auk, 112: 146-155.
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Global Short Term Trend: Relatively stable (=10% change)

Comments: North American Breeding Bird Survey (BBS) data indicate a significant 1.9% annual decline (29% overall) occurred in North America from 1966 to 1999, and the last half of this period (1980-1999) showed a significant 1.5% annual decrease (15.3% overall) (Sauer et al. 2000). Regionally, BBS data indicate that there were significant population declines in eastern North America in the periods 1966-1999 (2% annually) and 1980-1999 (1.6% annually); and a significant 2.8% annual decrease in central North America, 1966-1979 followed by a significant 2.4% annual increase 1980-1999 (Sauer et al. 2000). Where the species is most often detected on BBS routes (e.g. Cumberland Plateau), a significant 2% annual decline is indicated for 1966-1999 and a significant 4.1% annual decline for 1980-1999 (Sauer et al. 2000). Witham and Hunter (1992) studied population trends of Neotropical migrant landbirds in northern coastal New England. Wood thrush showed declines in all analyses, but most significantly for the period 1983-1988 (percent change per year = -7.30). Numbers have been counted in migration at Long Point, Ontario, Canada, since 1961. Wood Thrushes declined over each decade (1961-1970, 1970-1979, and 1979-1988), most alarmingly in the 1979-1988 period, with a significant 15% per year decrease; the net change over the entire 30-year period is also significant and negative (-6% per year) (Hussell et al. 1992). Numbers were found to decline between 1985 and 1989 in small forest fragments in Illinois of 14, 25, and 65 ha in size (Robinson 1992). At Hubbard Brook Experimental Forest, New Hampshire, during the period 1969-1986, the population showed a highly significant decline similar to that reflected by statewide BBS data (Holmes and Sherry 1988).

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Population

Population Trend
Decreasing
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Threats

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: Habitat degradation and fragmentation are commonly cited as the biggest threats. With loss of habitat and increased conversion to agriculture and pine plantations, both brood parasitism and nest predation increase. The Brown-headed Cowbird (MOLOTHRUS ATER) is by far the most serious threat, causing significant population declines throughout much of the range. Despite the fact that cowbirds are such a problem, control of cowbird numbers rarely has been attempted. Rate and impact of cowbird parasitism is highest in the Midwest, lowest in the Northeast (Hoover and Brittingham 1993). In forest fragments in northern Indiana, 90% of 278 nests contained an average of 2.4 cowbird eggs/parasitized nest; there was no relationship between size of forest fragment and cowbird parasitism but the entire landscape "appeared to be part of a regional sink for Wood Thrushes" (Fauth 2000). Data were collected from fragmented forests in Illinois by Robinson (1992), where thrushes also suffered extraordinarily high rates of brood parasitism. Of 19 nests found, all were parasitized with an average of 1.2 host eggs per nest, and an average of 4.6 cowbird eggs per parasitized nest; thrushes raised far more cowbirds than they did wood thrushes. Of 15 thrush nests found during the incubation period, only a single thrush fledgling was produced. One nest had 12 cowbird eggs in it. Similar results have been found for the Shawnee National Forest of southern Illinois, although parasitism rates are somewhat lower--89% of 83 nests contained an average 3.2 cowbird eggs per parasitized nest (Robinson and Wilcove 1994). On four separate occasions, Hoover (1992) witnessed common grackles (QUISCALUS QUISCULA) preying on all of the eggs in four different nests (blue jay [CYANOCITTA CRISTATA] and American crow [CORVUS BRACHYRHYNCHOS] were likely to be other avian nest predators). Brood parasitism by cowbirds was less prevalent in Hoover's (1992) study, 18% and 6% of all nests being parasitized in 1990 and 1991, respectively. Nest records for 896 nests (Cornell Laboratory of Ornithology) indicated that rates of brood parasitism differed significantly among the Midwest (42.1%), the mid-Atlantic (26.5%), and the Northeast (14.7%) regions of the U.S. Because of the high abundance of cowbirds, high percentages of nests parasitized, and high numbers of cowbird eggs per parasitized nest, the effects of cowbird parasitism are particularly detrimental to populations in the Midwest. Another possible threat includes loss of forest undergrowth due to overgrazing by high deer populations. On the other hand, dense herbaceous growth resulting from waste-water irrigation is detrimental (Rollfinke et al. 1990). Loss of tropical forests also may contribute significantly to regional declines in temperate North America.

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Management

Restoration Potential: Although numbers are declining, there is no need of restoration in any state. However, should the need arise, restoration should be possible if fragmentation of habitat and edge effects can be minimized; this in turn should minimize the impact of cowbirds and nest predators.

Preserve Selection and Design Considerations: The key habitat requirement is a moist woodland understory of deciduous shrubs or saplings; bottomland and other rich hardwood forests are prime examples. Pine forests with a deciduous understory are also used, as are well-wooded residential areas. These habitat types should be a part of any preserve design considerations. As important as habitat type is preserve size. Nest predation and cowbird parasitism rates are higher in small woodlots and along the edges of larger tracts than in the interior of large tracts. Data from fragmented forests in the Midwest show that reproductive rates probably were well below levels necessary to compensate for adult mortality (Robinson and Wilcove 1994). Fragmented forests may therefore be population sinks with populations sustained by immigration from larger, unfragmented forest tracts. These data emphasize the importance of protecting large, unfragmented forests for breeding habitat.

Research on the effects of forest patch size on nesting success has direct implications for preserve design considerations. Hoover (1992) studied thrushes during 1990 and 1991 on 11 tracts of forest ranging in size from 9.2 ha to greater than 500 ha. Nesting success was significantly different between small and large forests (43% and 76%, respectively). Nest survival from 1990-1991 was positively correlated with forest area, forest core area, and percent forest within a 2-km radius of each study site. Nest depredation was significantly different between small and large forests (56% and 19%, respectively) and was the primary cause of nesting failure. Visitation by mammalian nest predators to scent-sign-posts was significantly different between small and large forests (41% and 14%, respectively), and relative abundance of avian nest predators was significantly higher on the small forests than on the large. Brood parasitism by cowbirds was also significantly different between small and large forests (13% and 4%, respectively) although had little influence on nesting success. Interestingly, Hoover (1992) found thrushes to be common on smaller tracts of forest, but that such birds had lower reproductive success because of high rates of nest depredation.

Large areas of forest are most favorable for breeding, though minimum patch size requirements are unclear. In Pennsylvania, nesting success was 86% in contiguous forest (> 10,000 ha), 72% in forest fragments larger than 100 ha, and 43% in small fragments of less than 80 ha; these differences were related to increased predation in the smaller forest tracts; cowbird parasitism had little influence on nesting success (Hoover et al. 1995). Whitcomb et al. (1981) reported that thrushes were present in small forest fragments (1-14 ha), but were almost twice as common if woodlots were larger than 70 ha. Thrushes were found by Galli et al. (1976) and Lynch (1987) to be more abundant in larger forest patches compared with smaller ones. In general, it appears that forest patches exceeding 100 ha are best suited for successful nesting because rates of nest predation and sometimes cowbird brood parasitism are lower. Thrushes require only small territories (< 1 ha) and seem to be able to maintain stable populations on small, isolated forest fragments in some cases (e.g., a 15-ha woodlot (Roth and Johnson 1993)). Some woodlots as small as 5 ha may be acceptable (Pinkowski 1991).

These results warn of the dangers of assuming that small fragments are acceptable just because they contain many birds; instead, we must determine reproductive success in addition to abundance relationships before we make accurate conclusions about habitat quality. Hoover (1992) concluded that to reverse decreasing population trends, land-use practices that maximize forest area and forest core area are needed.

Management Requirements: The effects of silvicultural practices such as clearcutting and selective logging on migratory songbirds may depend upon the landscape context (Robinson and Wilcove 1994). Preliminary evidence from the fragmented Shawnee National Forest of southern Illinois suggests that selective logging can have relatively little impact on thrushes. Robinson and Wilcove (1994) tentatively proposed that low-volume selective logging be used as an alternative to clearcutting. Logging roads should be closed and revegetated soon after harvest, and rotation times should be lengthened to permit regeneration of large, old trees.

The importance of protecting large, unfragmented forests for breeding habitat cannot be overstated. Where possible, forest preserves should be on the order of 10,000+ ha because cowbirds routinely commute up to seven kilometers between feeding and breeding sites. Fragmented forests might benefit from consolidation of ownership and forest regrowth within the largest tracts. Where necessary, cowbird control might be tried within the core of the largest tracts.

Vegetation patterns associated with successful reproduction need to be identified; then appropriate management plans can be devised. Thrushes are classified as closed-canopy obligate species and will tolerate uneven-age management forest stands (Crawford et al. 1981); single-tree selection (removal of mature trees as scattered individuals throughout the stand) and thinning understory trees that compete for root space will create favorable conditions for this species. Light diameter-limit cutting that removes only the best trees from the stand would be tolerated. Any intermediate or harvest cutting that opens the canopy will probably be detrimental.

Management Research Needs: Minimum area requirements for source populations seem to be the least understood aspect of management. Vegetation characteristics associated with nest-site selection and reproductive success also need to be quantified. Also, we need to understand better the role of tropical deforestation in the decline of regional thrush populations; habitat fragmentation on temperate breeding grounds cannot alone explain these declines.

Comments: Other research has concerned habitat selection and competition (Noon 1981), homing behavior (Able et al. 1984), taxonomy (Winker and Rappole 1988), mass variation in breeding birds (Johnson et al. 1990), and several aspects of wintering populations in southern Veracruz (Rappole et al. 1989, Winker et al. 1990).

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Global Protection: Few to several (1-12) occurrences appropriately protected and managed

Comments: Undoubtedly protected in several parks and preserves, though habitat management may not be ideal in all areas.

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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Positive

The benefits of wood thrushes toward humans are unknown.

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Economic Importance for Humans: Negative

Conservation of wood thrush habitat may conflict with other human desires, such as development of land for housing or other uses.

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Economic Importance for Humans: Positive

The benefits of wood thrushes toward humans are unknown.

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Risks

Stewardship Overview: Common throughout much of the eastern U.S. and most often found in deciduous or mixed forests with a fairly well-developed deciduous understory, especially where moist. Closed canopies are required. BBS data show this species to be most common in West Virginia, New Hampshire, and Maryland, with the Cumberland Plateau of the Appalachian Mountains being the most heavily populated Physiographic Region. Analyses of population trends show declines on regional and global scales. These declines are apparently due to loss and fragmentation of habitat, which has caused increased rates of nest predation and brood parasitism. In some areas of the Midwest, for example, thrushes are producing more cowbirds than thrushes, and avian nest predators such as grackles and crows are a serious threat. Tropical deforestation may also be a major threat to this species. Management recommendations are that forests be left unfragmented and low-volume selective cutting be used as an alternative to clear cutting where possible. Management needs include determination of key vegetation types associated with nesting success and a better understanding of minimum patch size requirements for source populations. Long-term monitoring of breeding productivity should be conducted wherever possible.

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Wikipedia

Wood thrush

The wood thrush (Hylocichla mustelina) is a North American passerine bird. It is closely related to other thrushes such as the American robin and is widely distributed across North America, wintering in Central America and southern Mexico. The wood thrush is the official bird of the District of Columbia.[2]

The wood thrush is a medium-sized thrush, with brown upper parts with mottled brown and white underparts. The male and female are similar in appearance. The song of the male is often cited as being the most beautiful in North America.

The wood thrush is an omnivore, and feeds preferentially on soil invertebrates and larvae, but will also eat fruits. In the summer, it feeds on insects continuously in order to meet daily metabolic needs. It is solitary, but sometimes forms mixed-species flocks. The wood thrush defends a territory that ranges in size from 800 to 28,000 m2 (960 to 33,490 sq yd). The wood thrush is monogamous, and its breeding season begins in the spring; about 50% of all mated pairs are able to raise two broods, ranging in size from two to four chicks.[3]

Taxonomy[edit]

The only member of the genus Hylocichla, the wood thrush was described by German naturalist Johann Friedrich Gmelin in 1789. The generic name is a direct translation of its common name, derived from the Greek words hyle/ύλη "woodland" and cichle/κιχλη "thrush" or "fieldfare".[4] The specific name comes from the Latin mustela "weasel".[5] It is closely related to the other typical American thrushes of the genus Catharus, and is sometimes merged into that genus.[6] It has been considered close to the long-distance migrant species of that genus, as opposed to the generally resident nightingale-thrushes, but this appears to be erroneous.[7] The wood thrush also appears to be fairly closely related to the large Turdus thrushes, such as the American robin.

Description[edit]

In Central Park, New York City

The adult wood thrush is 18 to 21.5 cm (7.1 to 8.5 in) long, with a wingspan of 30 to 40 cm (12 to 16 in) and a body mass of 48 to 72 g (1.7 to 2.5 oz).[8] Among standard measurements, the wing chord is 9.6 to 11.6 cm (3.8 to 4.6 in), the bill is 1.6 to 2 cm (0.63 to 0.79 in) and the tarsus is 2.8 to 3.3 cm (1.1 to 1.3 in). It is distinctly larger than the Catharus thrushes with which the species is often sympatric but slightly smaller than the common American robin.[9] The longest known lifespan for a wood thrush in the wild is 8 years, 11 months.[10] The crown, nape, and upper back are cinnamon-brown, while the back wings, and tail are a slightly duller brown. The breast and belly are white with large dark brown spots on the breast, sides, and flanks. It has white eye rings and pink legs.[11] Other brownish thrushes have finer spotting on the breast.[12] The juvenile looks similar to adults, but has additional spots on the back, neck, and wing coverts. The male and female are similar in size and plumage.

Vocalizations[edit]

The wood thrush has been reported to have one of the most beautiful songs of North American birds.[12] American naturalist Henry David Thoreau wrote:

Whenever a man hears it he is young, and Nature is in her spring; wherever he hears it, it is a new world and a free country, and the gates of Heaven are not shut against him.

While the female is not known to sing, the male has a unique song that has three parts. The first subsong component is often inaudible unless the listener is close, and consists of two to six short, low-pitched notes such as bup, bup, bup. The middle part is a loud phrase often written ee-oh-lay, and the third part is a ventriloquial, trill-like phrase of non-harmonic pairs of notes given rapidly and simultaneously.

The male is able to sing two notes at once, which gives its song an ethereal, flute-like quality.[13] Each individual bird has its own repertoire based on combinations of variations of the three parts. Songs are often repeated in order. The bup, bup, bup phrase is also sometimes used as a call, which is louder and at a greater frequency when the bird is agitated.[3] The wood thrush also use a tut, tut to signal agitation.[10] The nocturnal flight call is an emphatic buzzing heeh.[8]

Distribution and habitat[edit]

The wood thrush's breeding range extends from Manitoba, Ontario and Nova Scotia in southern Canada to northern Florida and from the Atlantic coast to the Missouri River and the eastern Great Plains. It migrates to southern Mexico through to Panama in Central America in the winter, mostly in the lowlands along the Atlantic and Pacific coasts.[12] It generally arrives on the U.S. Gulf Coast during the first week of April. Fall migration usually begins in mid-August and continues through mid-September. Migration takes place at night,[10] allowing them to find their direction from the stars and orient themselves by detecting the Earth's magnetic field.[14]

The wood thrush prefers deciduous and mixed forests for breeding. It prefers late-successional, upland mesic forests with a moderately-dense shrub layer. Robert I. Bertin (1977) found that this thrush favors areas with running water, moist ground, and high understorey cover.[10] The breeding habitat generally includes trees taller than 16 m (52 ft), a fairly open forest floor, moist soil, and leaf litter, with substrate moisture more important than either canopy cover or access to running water. The wood thrush can breed in habitat patches as small as 0.4 hectares (0.99 acres), but it runs the risk of higher predation and nest parasitism.[10] The wood thrush's breeding range has expanded northward, displacing the veery and hermit thrush in some locations. In recent times, as a result of fragmentation of forests, it has been increasingly exposed to nest parasitism by brown-headed cowbirds, as well as loss of habitat in the winter range.

Conservation status[edit]

The wood thrush has become a symbol of the decline of Neotropical songbirds of eastern North America, having declined by approximately 50% since 1966.[8] Along with many other species, this thrush faces threats both to its North American breeding grounds and Central American wintering grounds. Forest fragmentation in North American forests has resulted in both increased nest predation and increased cowbird parasitism, significantly reducing their reproductive success. A study by the Cornell Laboratory of Ornithology was the first large-scale analysis that linked acid rain to this thrush's decline.[15] Continued destruction of primary forest in Central America eliminated preferred wood thrush wintering habitats, likely forcing the birds to choose secondary habitats where mortality rates are higher. In spite of this, the wood thrush is still considered to be of least concern.[1]

Vagrancy[edit]

The wood thrush has occurred as a vagrant once in Europe, on Wingletang Down, St Agnes, Isles of Scilly, England on 7 October 1987.[16][17]

Behavior[edit]

The wood thrush is primarily solitary, but occasionally forms mixed-species flocks in the winter. Its breeding territory ranges from 800 to 8,000 m2 (960 to 9,570 sq yd) in size, and are used for nesting, gathering nest materials, and foraging.[10] Some wood thrushes also defend a feeding territory in the winter. Territorial interactions are usually settled without physical contact, but in high-intensity encounters or nest defense, physical interactions with the feet or bill have been observed. Defense behaviors in response to nest predators include wing flicks, tail flicks, and raising the crest, sometimes escalating to dives and strikes.[10]

This species has also been observed displaying a behavior known as "anting." Anting occurs when a bird picks up a single ant or group of ants and rubs them on its feathers. The purpose of this behavior is unknown, but it is thought that the birds may be able to acquire defensive secretions from the ants possibly used for some medicinal purposes, or that it simply supplements the birds' own preen oil.[8]

Diet[edit]

Soil invertebrates and larvae make up most of the wood thrush's omnivorous diet, but it will also eat fruits in the late summer, fall, and late winter. It occasionally feeds on arboreal insects, snails, and small salamanders. The young are fed insects and some fruit.[8] After breeding and before migration, the wood thrush will switch from insects to fruits with high lipid levels. In the summer, low fruit consumption and lipid reserves require the bird to feed on insects continuously in order to meet its metabolic needs.[10]

The wood thrush forages mainly on the forest floor, flipping leaves over with their bills to reveal insects. It can be observed hopping around in leaf litter and on semi-bare ground under the forest canopy. Fruits are swallowed whole.[10]

Predation[edit]

Eggs and chicks are vulnerable to chipmunks, raccoons, blue jays, American crows, black rat snakes, brown-headed cowbirds, common grackles, southern flying squirrels, gray squirrels, least weasels, white-footed mice, domestic cats, great horned owls, and sharp-shinned hawks. Adults are primarily taken by hawks and owls.[10]

Reproduction[edit]

Nesting in Pennsylvania, USA

Wood thrushes are monogamous. Breeding pairs form in mid-April to early-May, and usually last throughout the breeding season. Most thrushes find a new mate each year, and mate guarding and extra-pair copulations have not been observed in this species.[10]

Some male wood thrushes arrive at the breeding grounds several days before the earliest females while other males arrive at the same time as the females, establishing territories ranging in size from 0.08 to 0.8 hectares (one-fifth of an acre to two acres).[3] The female typically leads silent circular flights 1–1.8 m (3.3–5.9 ft) from the ground, with the male chasing. Six or more flights generally take place in succession. The pairs will perch together and feed each other in between flights.[8] The male begins to sing at dawn and dusk a few days after arriving at breeding grounds. Early in the breeding season, the male sings from high perches in the tallest trees, but as the season progresses, it sings somewhat shorter and less elaborate songs from lower perches. Each day's singing begins and is most intense just before sunrise. The male may sing throughout the day but especially at dusk. The song season is usually over by the end of July.[10]

Typically, the female chooses the nest site and builds the nest. However, there has been some indication that the male is able to influence the selection of the nest site by perching nearby and singing. Usually, though, the female chooses whether or not to accept or reject the nest site suggested by the male.[18] The nest is usually sited in a dense patch of vegetation in a tree or shrub that provides concealment and shade. It is usually made of dead grasses, stems, and leaves, and lined with mud, and placed in a fork at a horizontal branch. The nest is not reused. Usually, two broods are attempted, although three to four separate nests may be built before a pair succeeds. Two to four pale blue eggs are laid at the rate of one per day.[19] The eggs are incubated by the female only for 11 to 14 days, with the average being 13 days. Like all passerines, the chicks are altricial at hatching, mostly naked with closed eyes.[20] The female broods the chicks during the first four days after hatching. Both parents feed the nestlings and remove fecal sacs from the nest. The chicks fledge 12–15 days after hatching, but the parents continue to feed them until they become independent and leave the parents' territory at 21–31 days old.

The young wood thrush is able to begin breeding the next summer. Most females lay their first eggs in mid-May, but older females may begin laying sooner. Pairs usually attempt to rear a second brood no later than late July, with the last of the young fledging around mid-August.[10] About half of all wood thrush pairs successfully raise two broods.[3]

References[edit]

  1. ^ a b BirdLife International (2012). "Hylocichla mustelina". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ^ "50 States". Retrieved 17 June 2007. 
  3. ^ a b c d Cornell Laboratory of Ornithology. "Wood Thrush". Archived from the original on 9 June 2007. Retrieved 17 June 2007. 
  4. ^ Liddell, Henry George and Robert Scott (1980). A Greek-English Lexicon (Abridged Edition). United Kingdom: Oxford University Press. ISBN 0-19-910207-4. 
  5. ^ Simpson, D.P. (1979). Cassell's Latin Dictionary (5 ed.). London: Cassell Ltd. p. 883. ISBN 0-304-52257-0. 
  6. ^ Kevin Winker and John H. Rappole (1988). "The Relationship between Hylocichla and Catharus (Turdinae)". The Auk 105 (2): 392–394. doi:10.2307/4087513. JSTOR 4087513. 
  7. ^ Winker, K.; Pruett, C. L. (2006). "Seasonal Migration, Speciation, and Morphological Convergence in the Genus Catharus (Turdidae)". The Auk 123 (4): 1052. doi:10.1642/0004-8038(2006)123[1052:SMSAMC]2.0.CO;2. JSTOR 25150219.  edit
  8. ^ a b c d e f Cornell Laboratory of Ornithology All About Birds. "Wood Thrush". Retrieved 17 June 2007. 
  9. ^ Thrushes by Peter Clement. Princeton University Press (2001). ISBN 978-0691088525
  10. ^ a b c d e f g h i j k l m University of Michigan Museum of Zoology. "Wood Thrush". Retrieved 17 June 2007. 
  11. ^ Skutch, Alexander Frank (1989). A Guide to the Birds of Costa Rica. Ithaca: Comstock. ISBN 0-8014-9600-4. 
  12. ^ a b c Bull J, Farrand, J Jr (1987). Audubon Society Field Guide to North American Birds:Eastern Region. New York: Alfred A. Knopf. pp. 666–667. ISBN 0-394-41405-5. 
  13. ^ Weidensaul, Scott (2007). Of a Feather: A Brief History of American Birding. New York: Harcourt, Inc. p. 237. ISBN 978-0-15-101247-3. 
  14. ^ Dan Lazar. "The Mysteries of Migration – Transmutation or Long-Distance Travelers?". Archived from the original on 15 March 2007. Retrieved 26 June 2007. 
  15. ^ Miyoko Chu, Stefan Hames. "Wood Thrush Declines Linked to Acid Rain". Retrieved 17 June 2007. 
  16. ^ Paul Dukes (1987). "A New British Bird – Wood Thrush on St Agnes". Twitching 1 (10): 299–300. 
  17. ^ Paul Dukes (1995). "Wood Thrush in Scilly: new to Britain and Ireland". British Birds 88 (3): 133–135. 
  18. ^ Hervey Brackbill. Nesting Behavior of the Wood Thrush (PDF) 70 (1). pp. 70–89. Retrieved 17 May 2007. 
  19. ^ D. A. Sibley. "Wood Thrush". Retrieved 17 May 2007. 
  20. ^ Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye. "Precocial and Atricial". Retrieved 6 May 2007. 
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Names and Taxonomy

Taxonomy

Comments: See Winker and Rappole (1988) for discussion of evidence indicating that the wood thrush does not warrant recognition as a genus (i.e., HYLOCICHLA) separate from CATHARUS.

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