Distinguishing Characteristics

Medium-sized to large, long-legged shorebird (290–330 mm long, 111–235 g; Cramp and Simmons 1983, Marchant et al. 1986), with pale-spotted dark brown upperparts and pale underparts. In Alternate plumage, develops heavy dark streaks on head and neck and barring on flanks and upper belly. Basic and Juvenal plumages are less heavily marked, especially below. Juvenal plumage is more spotted above, with distinct dark streaks on white breast. Sexes similar in plumage and size. Slender and long necked with long bright yellow legs and long dark bill give it an elegant, upright appearance. These features, in combination with back spotting, square white rump-patch, and lack of a wing-bar distinguish the 2 yellowlegs species from all other North American shorebirds (Marchant et al. 1986).

Very similar in all plumages to Lesser Yellowlegs, but latter is much smaller (approximately half the mass) and daintier, and has a straighter, thinner, and proportionately shorter bill (relative to head length). In Alternate plumage, dark barring on underparts is more extensive and heavier on Greater Yellowlegs; in Juvenal plumage, breast of Lesser Yellowlegs has gray brown wash, with streaks less distinct than those of Greater Yellowlegs. Greater typically has more extensive gray base on bill, although this varies. Differences in size and overall bulk are generally obvious when both species are seen together, but much less so in single birds. Other features can vary and overlap between species. Bill shape and size is perhaps the most useful way of distinguishing the species.

Vocalizations also differ. Greater has clearer, more ringing call and simpler song. Call of Lesser is sharper and more clipped; usually gives only 2 notes, compared to 3–4 of Greater. Number of notes given by each species varies, however, and tone of notes is more reliable than number for identifying species (Wilds 1982, Marchant et al. 1986, Kwater 1992, Paulson 1993).

Common Greenshank, a Palearctic species very rarely recorded in North America, is structurally similar to Greater Yellowlegs, though slightly bulkier, with thicker neck; much duller legs; slightly paler, less spotty, upperparts; shorter wings; and white rump-patch extending up back.