Calidris canutus rufa is a subspecies of red knot occurring in the western hemisphere. Birds are characterized by a stocky body, a short black bill, dark olive to gray legs, and white rump coloration that does not extend up the back (Terres 1980; Paulson 2005). Plumage and body coloration varies with age and season, and descriptions are divided accordingly below. Breeding Adult The face and underparts are reddish, with brownish black or mottled black and white markings on the majority of the body. The belly is marked with variable amounts of white, and the posterior sides and undertail bear sparse black bars. Males are generally more colorful than females, with more red coloration on the upperparts, smaller white patches on the belly and fewer bar markings on the breast (Peterson 1980; Terres 1980; Paulson 2005). Non-breeding Adult Plumage is white or light brown below, with gray-brown darkly streaked upperparts. Legs are greenish and paler than those of breeding adults (Peterson 1980; Terres 1980; Paulson 2005). Juvenile Legs are greenish and often paler than those of the adult forms. Plumage coloration is similar to non-breeding adults, but with the breast often more prominently marked with fine brown streaks instead of dots. Younger juveniles may have buff underparts (Peterson 1980; Terres 1980; Paulson 2005).