Appearance

Nestlings downy and precocial. Under-parts grayish white, upperparts warm buff and blackish brown, down with fine white tips (Harrison 1978). Primaries about 90% emerged by day 22, little down present, and Juvenal plumage nearly complete (CLG-T).

Juvenal plumage completely attained before fall migration. First Prebasic molt may be incomplete, and occurs at wintering area. Most yearlings retain some old inner primaries, secondaries, and under wing coverts (Spaans 1979, Gratto and Morrison 1981, CLG-T), so most yearlings can be identified by differential primary wear. Adults undergo one complete flight feather molt and two body feather molts per year, primarily on wintering grounds (Spaans 1984). On breeding grounds in Manitoba, adults initiate partial body molt (head, back, breast) during late incubation (Gratto 1983). Further body molt may occur during fall migration (James Bay, Ont.: CLG-T). While some adults migrating through Kansas in fall are apparently in active wing molt (Martinez inSpaans 1979), those migrating through James Bay, Bay of Fundy, Maine and Saskatchewan in fall (P. Dunn pers. comm., CLG-T), and those arriving in Suriname, are not (Spaans 1979). Flight and body feather molt into Basic (winter) plumage completed in wintering area. Body feathers again molted on wintering grounds into Alternate (breeding) plumage, before spring migration. Adults show body molt in all months in Suriname, although individuals have a midwinter stop. Duration of primary molt in individuals is 2.5 to 3.5 months (Spaans 1979). In yearlings, partial primary molt from early Nov to mid-May; yearlings that summer in Suriname start complete primary molt following autumn in late July to mid-January; adult primary molt from mid-August to mid-January (Spaans 1979, pers. comm.).

Description

Juvenal.Upperparts drab gray or ochre brown, buff-colored rounded tips on median and lesser wing coverts. Distinct whitish supercilium that broadens behind eye, crown uniformly dark and coarsely streaked. Buff-colored upper chest (Cramp and Simmons 1983, Chandler 1989).

Basic (winter).Upperparts brownish gray, underparts white, white supercilium. Diffuse streaking on chest, less obvious than in Alternate plumage (Chandler 1989).

Alternate (breeding).Upperparts ochre brown, gorget marks brown and fine, widespread across chest and extending along flanks. Underparts below chest and upper flanks white, as is throat. Head streaked with brown, but not distinct pattern (Cramp and Simmons 1983).

Bill black, often straight with slightly thickened tip; iris black; legs and toes black; toes partly webbed.