Greater Yellowlegs

A fairly common presence in Sonoma County during the winter months and during spring and autumn migration. Generally not seen much from around mid-May to late July when breeding, mostly in northern Canada, but reported sporadically even then. Found near the coast in marshy areas and on tidal mudflats. Inland, Greater Yellowlegs favors ponds, flooded fields, and open areas in slow-moving streams. Most common in ponds, however, especially around shallow water with exposed muddy areas. Feeds on small fish, snails, worms, etc. Active forager. Sometimes seen chasing small fish. Usually solitary or in small groups (usually three or four, but I have personally seen as many as 33 together at one time--although that is quite unusual). Not uncommonly seen in association with Lesser Yellowlegs (Tringa flavipes).

A large, fairly slim sandpiper, striking for its deep yellow legs with knobby "knees" and almost checkered black, grey, and white back and wings. Long bill (almost one-and-a-half times as long as its head) may be slightly upturned at the tip and shows some paleness at the base in the non-breeding plumage we normally see in Sonoma County. Primaries black and conspicuous when folded over the tail. In non-breeding plumage, flanks and belly mostly clear white, making the folded wing stand out. In breeding plumage, throat, breast, and flanks become more heavily streaked or barred, bill becomes all black. Juvenile birds similar to winter (non-breeding) adults but with more heavily streaked neck.

Greater and Lesser Yellowlegs are the only large, long-legged shorebirds commonly present in the county with the combination of black, grey, and white markings and bright yellow legs. Telling the two apart can be tricky in some situations, but it's rarely impossible. The best distinguishing characteristics are bill length and overall size. Unfortunately, size is often difficult to judge and only occasionally do we get the opportunity to compare the two birds side by side. Bills are often hidden while birds poke in the mud. That said, Greater Yellowlegs is a larger bird (30-40% longer); its bill is longer (markedly longer than its head, while the bill of Lesser Yellowlegs is only slightly longer than its head); in the non-breeding plumage we see in Sonoma County, the base of the bill is usually irregularly pale in Greater Yellowlegs, while the bill is all black in Lesser Yellowlegs; Greater Yellowlegs will usually look paler overall (more white showing); leg color is virtually the same in the two birds, but Greater Yellowlegs has more prominent leg joints; in flight, both birds show all dark wings (no wing stripe) with pale rump and tail (photo below); voices are distinct, with Greater typically giving a strident series of three (or sometimes four) Whew! notes, while Lesser typically gives only one or two, somewhat less energetic-sounding notes (see links below). Greater Yellowlegs tends to be more active while foraging, while Lesser Yellowlegs picks more daintily.

The photo above is useful. The closer bird is Greater Yellowlegs, the background bird is Lesser Yellowlegs. At this angle, the size difference is not striking, but the closer bird is, in fact, larger. However, note the generally paler overall coloration of the foreground bird. Note that its bill shows the typical paleness at the base (the base of the bill of the Lesser Yellowlegs is all black). The "knees" (actually the intertarsal joints) are bigger in the Greater Yellowlegs. The bill length can't be compared here, but note that the bill of the foreground bird is much longer than the length of its head from front to back. That alone identifies this bird as Greater rather than Lesser Yellowlegs. Also see the photo of Lesser Yellowlegs below.