The hermit thrush (Catharus guttatus) is a medium-sized North American thrush. It is not very closely related to the other North American migrant species of Catharus, but rather to the Mexican russet nightingale-thrush. This species measures 15 to 18 cm (5.9 to 7.1 in) in length, spans 25 to 30 cm (9.8 to 11.8 in) across the wings and weighs 18 to 37 g (0.63 to 1.31 oz). Among standard measurements, the wing chord is 7.8 to 11.1 cm (3.1 to 4.4 in), the bill is 1.6 to 1.9 cm (0.63 to 0.75 in) and the tarsus is 2.7 to 3.3 cm (1.1 to 1.3 in). It is more compact and stockier than other North American Catharus thrushes, with relatively longer wings. The Hermit Thrush has the white-dark-white underwing pattern characteristic of Catharus thrushes. Adults are mainly brown on the upperparts, with reddish tails. The underparts are white with dark spots on the breast and grey or brownish flanks. They have pink legs and a white eye ring. Birds in the east are more olive-brown on the upperparts; western birds are more grey-brown.