BIRD OF THE WEEK: May 1, 2020
SCIENTIFIC NAME: Hylocichla mustelina
POPULATION: 12 million
HABITAT: Breeds in mature deciduous and mixed forests; winters in lowland and foothill tropical forests
The robust, long-legged Wood Thrush is closely related to the American Robin and thrushes of the genus Catharus, such as the Bicknell's Thrush and Swainson's Thrush. Its scientific name, Hylocichla mustelina, translates roughly as "weasel-colored woodland thrush," a reference to this bird's rich red-brown head, back, wings, and tail. A few of its more evocative folk names include Song Thrush, Swamp Angel, and Wood Robin.
Once a familiar summer sound throughout eastern U.S. forests, the Wood Thrush's haunting, flute-like song is, sadly, heard in fewer places these days. How do Wood Thrushes create such beautiful songs?
Like all songbirds, Wood Thrushes have a Y-shaped voice box called the syrinx. During his three-part song, a male actually sings pairs of notes simultaneously, which harmonize and blend to produce ringing, ethereal tones.
The Wood Thrush's complex song begins with several low, almost inaudible notes, followed by the rising, flute-like ee-oh-lay, finishing with a complex trill. Each bird can sing unique versions of each song part, and one male can easily sing over 50 distinct songs!
Another commonly heard vocalization is a rapid pit-pit-pit call, given by both sexes. This series is heard year round, including at dusk, as one of the last sounds these birds make before roosting.
Listen to the haunting song, and call, here:
The destruction and fragmentation of forests are major factors in the species' decline. Partners in Flight placed this thrush on its Yellow Watch List of declining birds, noting a 60-percent drop in population between 1970 and 2014.
Although Wood Thrushes will nest in well-wooded suburban areas, they have reduced breeding success in smaller forest patches due to cowbird parasitism and nest predation from jays, crows, raccoons, and domestic cats.
Wood Thrushes forage on the forest floor, flipping over leaves in search of insects, snails, and sometimes small salamanders in the manner of a Kentucky Warbler or Spotted Towhee. They will also eat small fruits, including dogwood, holly, and pokeweed berries, especially in the late summer and fall while building up fat to fuel their migratory treks.
Calcium-rich materials such as snail shells are particularly important to female Wood Thrushes, which need this mineral to successfully develop a clutch of eggs. Snails have declined in forested habitats due to the effects of acid rain, perhaps another driver of population declines.
The male arrives on the breeding grounds first, staking out a territory of up to several acres. The female arrives several days later, and the pair court in a series of circular flights and mutual feeding sessions.
The female chooses a nest site, usually in a young tree or shrub less than 20 feet above the ground. Like an American Robin, she incorporates a layer of mud into her cup-shaped nest. Interestingly, while the outside of the nest is usually made of dead grasses, some thrushes may add paper, cellophane, cloth, or other white materials. The contrasting color is thought to help to break up the nest's contour, making it less obvious to potential predators.
Wood Thrushes are seasonally monogamous, meaning a pair will stay together for the duration of one breeding cycle. However, extra-pair copulation is common, and up to 40 percent of a female's young may not be fathered by its mate! This breeding strategy likely promotes greater genetic diversity in the young, while assuring that a steady male remains to help feed the chicks and defend territory.
Since the male helps feed the young, the female has time to start a second nest and brood. Almost half of all mated pairs raise two broods, ranging in size from two to four chicks.
Our BirdsScapes approach to migratory bird conservation is aimed at reversing population declines. One important aspect of this approach is ensuring that economic opportunities for people coexist with protected habitat. For example, shade-grown coffee preserves some native trees and bird habitat among the coffee shrubs. One easy way to help the Wood Thrush — and other migratory birds, including Ruby-throated Hummingbird — is to buy Bird Friendly® coffee grown on certified farms within this bird's wintering range.
ABC works with partners throughout Latin America to create protected bird reserves, with El Jaguar Reserve in Nicaragua and many other ABC-supported properties known to support wintering Wood Thrushes, along with Golden-winged Warblers and many other species.
Other ABC initiatives tackle threats affecting all migratory birds, including our Cats Indoors program, which encourages pet owners to keep cats and birds safe, and our Glass Collisions program, which offers solutions to keep migrating birds from hitting windows.
Donate to support ABC's conservation mission!