Identifying yellowlegs could not be any easier

Shorebird identification rivals sparrow ID for all but the most experienced birders, particularly in the fall, when all shorebirds in nonbreeding plumage seem to be a single species, divided only by size.

Two species, however, make the ID process much simpler — to a degree.

Two of the most common shorebird species to pass through our area are the greater and lesser yellowlegs. Their name sets them apart. Among larger wading birds, they are the only two with yellow legs.

The upland sandpiper also has yellow legs and is between the two yellowlegs species in size at 12 inches in length, but it prefers fields, not water, and is famous for standing on fence posts. Other yellow-legged shore birds are much smaller than the two yellowleg species.

The two species of yellowlegs make for almost a singular avian biography. When only one bird is seen, it is often a challenge to name the species without being able to compare sizes, side by side.

The greater yellowlegs is 12-15 inches long with a wingspan of 23-26 inches. The lesser is 9½-11 inches long with a 19-21-inch wingspan.

Both have equally lemon-yellow legs, though some field guides note the greater species tends to be more orange. Both have long bills in relation to their sizes. The greater has a slightly upturned bill while the lesser shows a straight bill. Both bills are black, as are the eyes of both. Both often bob their bodies up and down as they feed.

The greater species may show a bit more streaking and heavier spotting and barring on the neck, sides and breast. The underparts are white and, in flight, both show a white rump and tail.

In both species, the female is slightly larger than the male and, of some importance to birders in Central Missouri, the lesser species often migrates in larger flocks.

Both species wade belly-deep in water, dabbing at food, not probing. They often swing their bills from side-to-side, often running after small fish.

The diets of each pretty much overlap — small fish, minnows, insects, water bugs, worms and some aquatic plants.

So what is different about these two yellowlegs except their size — where a female of the lesser may be almost as big as the male of the greater?

Heavier breast, neck and side streaking in breeding season (spring migration) and vocalization.

The greater’s voice is louder, clearer, repeating a whistle-like “few, few, few” three to five times. The lesser is less ringing in volume and is more of a “cu” or “cu-cu.”

At least that’s what the field guides tell Ol’ Clark, whose hearing is so bad he can’t hear either.

Both species are arriving in Central Missouri from as far away as Argentina en route to the Arctic as you read this. They will pass through as late as mid-May. There will be more lessers than greaters.

They both are among the earliest shorebird migrants in both spring and fall, arriving back in the area by late August.

When they return in the fall, their streaking and spotting will have faded some, but the legs and bills will not change. Nor will their vocalization. Those yellow/orange legs make ID easy when fall shorebirding can be as tough as fall warblers and female ducks, not to mention sparrows. Note, too, that in flight, the yellow legs of both stick out beyond the tail feathers.

You can find yellowlegs, greater or lesser, in mud flats, on creak and pools of rain water in agricultural fields.

Enjoy figuring out which is greater and which is lesser. ’Tis what makes birding fun.