Yellowlegs

Mixed assemblages of small shorebirds combing our coastal wetlands in spring are likely to be accompanied by several yellowlegs, immediately recognizable by their greater size. As the “peeps” scurry over the mud and along the waters edge, the yellowlegs, with a more careful, heron-like elegance, wade out into ponds and sloughs in search of different prey.

General description: Yellowlegs can be distinguished from other shorebirds by the long, straight or almost imperceptibly upturned bill and the very long, bright yellow legs. The neck is longer and more slender than that of most shorebirds. In flight, the wings are uniformly dark, lacking stripes, the rump and tail are almost completely white, and the legs extend well beyond the tail. Distinguishing between the two Alaskan species of yellowlegs is more difficult. Plumage of the two birds is nearly identical. None of the following distinctions are completely reliable by themselves, and if possible they should be used in conjunction with each other.

When seen together, as often occurs in migration, the greater yellowlegs (Tringa melanoleuca) stands 9-10 inches high (0.25 m), taller than the lesser yellowlegs (Tringa flavipes). The greater yellowlegs has a somewhat thicker bill than the lesser, and it may turn upward very slightly, while that of the lesser yellowlegs is slighter and quite straight. The calls of the two species are distinctive. The greater yellowlegs has a louder and clearer call, often uttered in a three- or four-note sequence, “kyew kyew kyew,” with a falling inflection to each syllable. The lesser yellowlegs tends to call once or twice. Both species of yellowlegs have a “yodelling” song in addition to the better known sharp alarm calls. This song is given either from the ground or during display flights and has been variously interpreted as “toowhee, toowhee,” “tweda, tweda,” or “whee-oodle, whee-oodle.” It is heard both on the breeding grounds and in migration.

The plumage of both species is darker in spring than fall. Birds seen in migration may wear transitional plumage. Both species “teeter” and bob as if improperly connected to their legs. This habit is also characteristic of the spotted and solitary sandpipers and of dippers. The “purpose” of this seemingly tiresome behavior is a favorite subject for speculation among birders, but no concensus has been reached. All of these birds spend considerable time in or near water.

Life history: Yellowlegs usually appear in southeast Alaska in late April. Some continue north to nest in southcoastal and southwest Alaska, with many lesser yellowlegs in central Alaska.

Four blotchy buff colored eggs are laid in an unlined depression in the moss. A nearby tree is often used as an observation post. At this time parents will dive threateningly at any predators and intruders that venture close to the nest.

Fall migration begins in late July and lasts through September. Wintering yellowlegs are scattered along the coast from South America through California and Oregon. In mild years greater yellowlegs winter as far north as southern Vancouver Island.

Behavior and feeding: The exaggerated legs of the Tringa genus are best explained by the custom of feeding in the water, often wading out beyond the belly depths of less elevated relatives. Among shorebirds, long bills usually accompany long legs for the same reason. The greater yellowlegs is an accomplished fisher, at times preying almost exclusively on small estuarine fishes such as sticklebacks and sculpins. Sometimes groups of feeding yellowlegs will form lines, wading abreast to corner fish in the shallows. Both yellowlegs, particularly the lesser, also eat invertebrates. Adults and larvae of aquatic insects such as water boatmen, diving beetles, dragonfly nymphs, and flies are important in the diet, as are sand fleas and intertidal amphipods. Terrestrial invertebrates such as ants, grasshoppers, snails, spiders and worms are also taken. In spite of the length of the yellowlegs bill, it is rarely used for probing in sand or mud. The greater yellowlegs will swing its bill from side to side in the water; the lesser yellowlegs does not.

In addition to tidal sloughs and mudflats, both species frequent the edges of freshwater lakes and ponds. Lesser yellowlegs occasionally swim, an unusual practice among shorebirds. The lesser yellowlegs seems somewhat more gregarious than the greater, although both are seen in loose flocks.

In the days of market hunting on the Atlantic Coast, shorebirds of many species were decimated by gunners, especially species like the golden plover, with the most pronounced flocking tendencies. Yellowlegs escaped this fate to some extent, because of their wariness and reputation as poor table fare. Their noisy alarm calls often foiled a hunter's stalk for more desirable birds, and the nickname of “tell-tale” dates to this period. But cautious as they were, yellowlegs were easily attracted by decoys or whistled imitations of their calls. Flocks of lesser yellowlegs would linger over the spot where one of their number was shot until many more were killed.

Tracks: Most migrating shorebirds forage on unvegetated terrain suitable for tracking. Learning to distinguish their tracks can be a useful additon to a birdwatcher's skills. Both yellowlegs walk with the middle toes pointing straight ahead (the majority of shorebirds are “pigeon-toed”). The greater yellowleg's toes are longer and relatively more slender. The junction of outer and middle toes are slightly webbed in each track of the greater yellowlegs but not in the lesser's. Tracks of greater yellowlegs average 2 1/8 inches in length; lessers average 1 3/8 inches.