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 )
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:
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
Other Physical Features: endothermic ; bilateral symmetry
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.
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
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
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
The benefits of wood thrushes toward humans are unknown.
Conservation of wood thrush habitat may conflict with other human desires, such as development of land for housing or other uses.
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
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
Perception Channels: visual ; tactile ; acoustic ; chemical
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: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
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)
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.
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.
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.[3]
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.[4]
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".[5] The specific name comes from the Latin mustela "weasel".[6] It is closely related to the other typical American thrushes of the genus Catharus, and is sometimes merged into that genus.[7] 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.[8] The wood thrush also appears to be fairly closely related to the large Turdus thrushes, such as the American robin. "Wood thrush" is the official name given to this species by the International Ornithologists' Union (IOC).[9]
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).[10] 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.[11] The longest known lifespan for a wood thrush in the wild is 8 years, 11 months.[12] 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.[13] Other brownish thrushes have finer spotting on the breast.[14] 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.
The wood thrush has been reported to have one of the most beautiful songs of North American birds.[14] 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.[15] 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.[4] The wood thrush also use a tut, tut to signal agitation.[12] The nocturnal flight call is an emphatic buzzing heeh.[10]
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.[14] 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,[12] allowing them to find their direction from the stars and orient themselves by detecting the Earth's magnetic field.[16]
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.[12] 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.[12] 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.
The wood thrush has become a symbol of the decline of Neotropical songbirds of eastern North America, having declined by approximately 50% since 1966.[10] 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.[17] 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 considered to be Least Concern.[1]
The wood thrush has been recorded twice as a vagrant in Europe, in Iceland at Kvísker in Öræfi East Skaftafellssýsla by Björnsson Hálfdán on 23 October 1967 and on Wingletang Down, St Agnes, Isles of Scilly, England on 7 October 1987.[18][19]
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.[12] 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.[12]
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.[10]
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.[10] 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.[12]
The wood thrush forages mainly on the forest floor, flipping leaves over with its 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.[12]
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.[12]
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.[12]
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).[4] 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.[10] 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.[12]
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.[20] 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.[21] 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.[22] 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.[12] About half of all wood thrush pairs successfully raise two broods.[4]
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.
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.
