About Catharus ustulatus (Nuttall, 1840)
This species, known as Swainson's thrush with the scientific name Catharus ustulatus (Nuttall, 1840), measures 16–20 cm (6.3–7.9 in) in total length. Its average wingspan is 30 cm (12 in), with a wing chord length of 8.7–10.5 cm (3.4–4.1 in). The bill is 1.5–1.9 cm (0.59–0.75 in) long, and the tarsus ranges from 2.5 to 3.1 cm (0.98 to 1.22 in) in length. Body mass of this species can fall between 23 and 45 g (0.81 to 1.59 oz). Like other Catharus thrushes, this thrush has the characteristic white-dark-white underwing pattern. Adult individuals have brown upperparts. Their underparts are white with brown coloring on the flanks, and the breast is lighter brown with darker spots. They have pink legs and a light brown eye ring. Eastern populations of this species have more olive-brown upperparts, while western populations are more reddish brown. The song of this bird is a hurried series of flute-like tones that spiral upwards. The breeding habitat of Swainson's thrush is coniferous woods with dense undergrowth across Canada, Alaska, and the northern United States. They also breed in deciduous wooded areas on the Pacific coast of North America. These birds are migratory, traveling to southern Mexico and as far south as Argentina for the winter. Coastal subspecies migrate down the Pacific coast of North America and winter from Mexico to Costa Rica. Continental populations take a substantial detour, migrating eastwards within North America before traveling southwards via Florida to winter from Panama to Bolivia. Swainson's thrush is a very rare vagrant to western Europe, and has also occurred as a vagrant in northeast Asia.
