Bird of the Week- Greater and Lesser Yellowlegs

Bill Rowe

It’s May, and millions of birds are pouring through the central United States right now, some of them stopping here for the summer to nest, others heading farther north and found here only in transit. Nearly all of our many shorebirds are of the latter type, and among the best known and most easily observed are the two species of yellowlegs. These trim, long-legged sandpipers are fun to watch as they fly about in compact, darting flocks or forage in our wetlands, wading in shallow water; they are also an important part of one’s shorebirding experience, forming a good basis for comparison with other less common or less obvious species. Unlike many of our other shorebirds (including the American Golden-Plover and Pectoral Sandpiper, both earlier Birds of the Week), the two yellowlegs don’t go as far as the arctic tundra to breed: Canada and Alaska yes, but mostly the vast forested areas south of the tundra, where they nest in boggy openings called muskeg. The range of the Greater Yellowlegs extends farther east, into Quebec and Labrador, while that of the Lesser goes farther west and north, but there is a lot of overlap, as there also is in the habits, diet, and appearance of these close cousins. Their behavioral differences are somewhat predictable, e.g., the Greater can wade in deeper water and catch larger prey, and it tends to occur in smaller flocks. But we tend to see them at the same times in the same habitats, and overall they make a pretty tight-knit pair. They will be nearly all gone by the end of May, but because shorebirds begin their fall migration very early (in July), it won’t be long before the first southbound yellowlegs show up again.

IDENTIFICATION: It’s easy to tell a yellowlegs: both of them are elegant gray sandpipers with very long legs that are bright yellow. Greaters average 3-4 inches longer, a size difference that is obvious when the two are side by side but not when they are separated. Then you can apply some rules of thumb: (1) When a Killdeer is around, compare body size: if the yellowlegs is about the same, it’s a Lesser, and if it’s notably bigger, it’s a Greater. (2) OK, no Killdeer, so look at the bill: if it is straight, all black, and hardly longer than the head, your bird is a Lesser; if it is paler at the base, noticeably longer than the head (up to 50%), and maybe a tiny bit upturned, the bird is a Greater. See photos above. (3) Ask the bird to call. If gives a loud, shrill, three-note whistle (tew-tew-tew!), it’s a Greater, and if the calls are more subdued and mostly two syllables, it’s a Lesser. Both species, in flight, have a solid dark back and wings with a contrastingly white rump and tail and trailing yellow legs.

ST. LOUIS STATUS: Very common migrants in wetland habitats, March through May and again July through October, sometimes stretching into November or, very rarely, December.

Learn more and listen to the songs and calls of Greater Yellowlegs here and Lesser Yellowlegs here.

A Lesser and a Greater together.

Photo Credit: Al Smith