Swainson's Thrush

This species is 16–20 cm (6.3–7.9 in) in length. The wingspan averages at 30 cm (12 in) and the wing chord is 8.7–10.5 cm (3.4–4.1 in). The bill measures 1.5–1.9 cm (0.59–0.75 in) in length and the tarsus is 2.5 to 3.1 cm (0.98 to 1.22 in) long. This species' body mass can range from 23 to 45 g (0.81 to 1.59 oz). This thrush has the white-dark-white underwing pattern characteristic of Catharus thrushes. Adults are brown on the upperparts. The underparts are white with brown on the flanks; the breast is lighter brown with darker spots. They have pink legs and a light brown eye ring. Birds in the east are more olive-brown on the upperparts; western birds are more reddish brown. This bird's song is a hurried series of flute-like tones spiralling upwards.

The breeding habitat of Swainson's thrush is coniferous woods with dense undergrowth across Canada, Alaska, and the northern United States; also, deciduous wooded areas on the Pacific coast of North America.

They forage on the forest floor, also in trees. Swainson's thrushes mainly eat insects, fruits and berries. They make a cup nest on a horizontal tree branch. A study in the White Mountains of New Hampshire found that Swainson's thrushes eat different insects depending on their elevation, with detritivores, particularly woodlice and ghost spiders, making up more of their diet at higher elevations. These prey items are generally more abundant at higher elevations but are also more nutrient-poor. Its song is said by local tribes to make salmonberries ripen, including the Saanich people who claim the bird says, "xwexwelexwelexwelexwesh!" meaning "ripen, ripen, ripen, ripen!" A similar belief appears among the Tlingit, Haida, Haisla, Oweekeno, Kwakwaka'wakw, Nuu-Chah-Nulth, Ditidaht, Sḵwx̱wú7mesh, and the Straits Salish people.

The genus name Catharus comes from the Ancient Greek katharos, "pure or clean" and refers to the plumage of the orange-billed nightingale-thrush C. aurantiirostris. The specific ustulatus is Latin for "burnt", from urere, "to burn".