Swainson's thrush (Catharus ustulatus ), also called olive-backed thrush and russet-backed thrush, is a medium-sized thrush. It is a member of genus Catharus and is typical of it in terms of its subdued coloration and beautiful, ascending flute-like voice. Swainson's thrush was named after William Swainson, an English ornithologist.
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 ustuatus is Latin for "burnt", from urere, "to burn".
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
Oviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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MigratingAnimal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migrati...
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starts withThis 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.
These birds migrate to southern Mexico and as far south as Argentina. The coastal subspecies migrate down the Pacific coast of North America and winter from Mexico to Costa Rica, whereas the continental birds migrate eastwards within North America (a substantial detour) and then travel southwards via Florida to winter from Panama to Bolivia. Swainson's thrush is a very rare vagrant to western Europe. It has also occurred as a vagrant in northeast Asia.
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.
This species may be displaced by the hermit thrush where their ranges overlap. Possibly, the latter species adapts more readily to human encroachment upon its habitat. At least in the winter quarters, Swainson's thrush tends to keep away from areas of human construction and other activity.
