Gray-cheeked Thrush Life History

Habitat

Gray-cheeked Thrushes nest from easternmost Russia, across Alaska, and throughout northern Canada, mostly in habitats where the boreal forest (taiga) begins to give way to tundra. In Alaska and Russia, the subspecies aliciae has adapted to a great variety of shrubby and open wooded habitats, among them thickets of alder and willow along rivers and bogs, spruce forests near timberline, and in shrubbery in open woodlands, below cottonwoods, on hillsides, and on glacial moraines. Here, the species avoids areas with only low shrub cover (under 3 feet) but thrives in open coniferous forests with a well-developed shrub layer of dwarf birch, currant, rose, raspberry, blueberry, or similar understory plants.

In Newfoundland and adjacent areas of northeastern Canada, the subspecies minimus is found in habitats associated with the southern boreal forest: mature spruce forests with heavy, tall shrub cover, coastal conifer thickets and conifer scrub, old-growth balsam fir forests, and clearcuts with regenerating balsam fir. Migrating Gray-cheeked Thrushes can turn up almost anywhere, but they select secluded areas with dense shrubs and ripe fruit when available. In South America, wintering birds occur in a great variety of woodlands, second growth, thickets, and plantations.

Food

Gray-cheeked Thrushes are omnivores, like other thrush species. Most of the diet during the breeding season consists of insects, especially beetles, flies, wasps, bees, ants, caterpillars, and grasshoppers; they also eat spiders. The birds find prey by hopping quietly along the forest floor, watching and listening, and occasionally making rapid vibrations with a foot to scare up insects. They seize prey with a quick peck. During the nonbreeding months, including on migration, fruit is important. Gray-cheeked Thrushes eat fallen fruit from the forest floor but also perch in trees to take ripening fruit. In tropical lowlands, Gray-cheeked Thrushes may join other bird species in following army ants, whose movements disturb and reveal prey items that the birds quickly consume.

Nesting

Nest Placement

It is likely that the female selects the site. Most nests are set in branch crotches of shrubs such as willow or alder, or in spruce or birch. Most are a few feet off the ground (rarely as high as 20 feet); some are built directly on the ground, at the base of spruce, willow, or fir trees.

Nest Description

The female constructs the nest. Nests set in shrubs and trees tend to be more tightly constructed than those built on the ground. The exterior is made of small twigs, rootlets, grass stems, or horsetail plants (Equisetum), the interior finished with lichen, moss, and fine grasses. Nest dimensions average about 4 inches across and 2.8 inches high, with interior cavity 2.5 inches across and 2 inches deep.

Nesting Facts

Behavior

Gray-cheeked Thrushes are shy birds of mostly remote habitats, and their courtship remains undescribed. Males arrive earlier than females in breeding areas and begin singing in May, when breeding locations are often still completely snow covered. At this time of year, they perch and sing in trees, on utility wires, and in open areas such as roadways, awaiting melt. Males are territorial and perform threat displays—pointing and opening the bill, raising the crown feathers, vibrating the foot, flicking and opening wings and tail—toward intruders of their species, and they often chase them in flight.

In related species that are better studied, such as Veery and Bicknell’s Thrush, dominant males often permit other pairs of their species to forage and nest within their territorial boundaries. Whether this represents partly cooperative or colonial breeding is not clear, but observations of multiple singing Gray-cheeked Thrushes within small patches of nesting habitat suggest that Gray-cheeked might have similar arrangements.

Conservation

Few data are available on population trends of Gray-cheeked Thrush, as its breeding areas are mostly very remote. Partners in Flight estimates a global breeding population of 46 million, of which 42 million breed in the U.S. and Canada. The species also nests in Russia. Partners in Flight rates the species a 9 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Threats to the species include destruction of breeding habitat by forestry and oil and gas exploration; and deforestation or other extraction activities in wintering habitats in South America. In Newfoundland, Gray-cheeked Thrushes have almost vanished from large parts of their former range where red squirrels were introduced in the late 1960s. The squirrels take eggs and nestlings of many bird species, including thrushes. Gray-cheeked Thrushes, like most songbirds that migrate nocturnally, often strike buildings and other structures and are killed.

Credits

American Ornithologists' Union (1995). Fortieth supplement to the American Ornithologists' Union Check-list of North American Birds. Auk 112:819–830.

Lowther, Peter E., Christopher C. Rimmer, Brina Kessel, Steven L. Johnson and Walter G. Ellison. (2001). Gray-cheeked Thrush (Catharus minimus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2021.1. Patuxent Wildlife Research Center, Bird Banding Laboratory 2021.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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