The Lesser Yellowlegs (Tringa flavipes) is a medium-sized shorebird that is a member of the sandpiper family Scolopacidae. It is a migratory bird that breeds in Canada and Alaska and winters primarily along the coasts of the southern United States, Mexico, and Central America. The Lesser Yellowlegs is known for its bright yellow legs and medium-length thin bill, which it uses to probe for food in the mudflats and shallow water of its coastal habitats. With their agile movements and loud “twee” calls, Lesser Yellowlegs are a distinctive sight during migration and on their wintering grounds. Keep reading to learn more about the identification, habitat, diet, breeding, conservation status, and other characteristics that define this elegant shorebird species.
Identification
The Lesser Yellowlegs reaches lengths of 8 to 10 inches, with a wingspan of about 16 to 19 inches. As their name suggests, Lesser Yellowlegs have bright yellow legs that contrast sharply with their gray plumage. Their medium-length bills are dark with a slight upward curve.
During the breeding season, Lesser Yellowlegs have bold black and white barred patterns on their backs and wings. Their undersides are white, and their tails have multiple thin horizontal black bars. In winter plumage, their upperparts are more uniformly gray. The Lesser Yellowlegs’ white rump patch and undertail coverts are key field marks year-round.
In flight, their thin pointed wings show a striking white bar on the coverts. Lesser Yellowlegs have swift and erratic flight patterns with rapid wingbeats.
Lesser Yellowlegs are often confused with the similar-looking Greater Yellowlegs. However, as their names denote, Lesser Yellowlegs are smaller in size than Greater Yellowlegs. Their bills are also shorter than those of Greater Yellowlegs. Lesser Yellowlegs have a bill length of 1.1 to 1.8 inches compared to Greater Yellowlegs’ bill length of 1.6 to 2.6 inches.
When viewed together, the bill length difference is apparent. Lesser Yellowlegs also have a smaller and more delicate overall appearance than the lankier Greater Yellowlegs. Their flight calls sound higher-pitched and softer than the loud, piercing flight calls of Greater Yellowlegs.
Habitat
During migration, Lesser Yellowlegs occupy a variety of wetland habitats, including flooded fields, ponds, marshes, wet meadows, river edges, reservoirs, tidal estuaries, and shorelines. On their wintering grounds, coastal habitats like salt marshes, tidal flats, sandy beaches, and mangrove forests are preferred.
In their Arctic and subarctic breeding territories, Lesser Yellowlegs inhabit open grassy or forest areas with numerous shallow wetlands. They may be found around ponds, bogs, fens, flooded meadows, shallow lakes, streams, and marshy tundra during the breeding season.
Diet
The diet of Lesser Yellowlegs consists primarily of small invertebrates that inhabit moist soils or shallow waters. They forage by wading in shallow water and stitching their bills into the mud to probe for prey. Their sensitive bill tips can detect slight vibrations to locate hidden animals.
Common food sources include insects like flies, beetles, dragonflies, damselflies; crustaceans including shrimp, amphipods, isopods; mollusks like snails and mussels; worms and other aquatic invertebrates. Lesser Yellowlegs may also eat tadpoles and small fish on occasion.
They employ a variety of foraging methods suited to their habitats – picking food from the water’s surface, probing mud or wet sand, gleaning along shorelines, and probing on the bottom in deeper waters. In the intertidal zone, receding tides concentrate prey and create prime feeding opportunities.
Breeding
Lesser Yellowlegs breed in the subarctic regions of central and western Canada and Alaska. They arrive on the breeding grounds in May. Their nesting territories are in open wetland areas, often with abundant shrubby vegetation nearby.
Both the male and female Lesser Yellowlegs contribute to building a simple scrape nest on the ground lined with grasses, leaves, lichens, and moss. Nest placement is near water but elevated to avoid flooding.
Lesser Yellowlegs lay a clutch of 3 to 5 eggs that are olive, brown, or greenish in color with dark brown spotting. The female incubates the eggs for 21 to 22 days while the male stays nearby to guard the territory.
The precocial young leave the nest within a day after hatching. Both parents tend the young, leading them to suitable feeding areas. The chicks fledge and become independent after about 3 to 4 weeks, at which point the adults begin their southbound migration. Lesser Yellowlegs first breed at 1 to 2 years of age.
Migration
Lesser Yellowlegs are long-distance migrants, wintering as far south as northern South America. They begin arriving at wintering grounds along the southern U.S. coast from July through October. Northbound migration occurs March through May.
During migration, Lesser Yellowlegs form large flocks, sometimes numbering in the hundreds of birds. They fly during day and night, stopping to rest and feed at wetlands along their migration route. Coastal areas, river mouths, and inland freshwater marshes provide key stopover habitat.
Lesser Yellowlegs have one of the longest migration routes of shorebirds. Birds breeding in Alaska traverse over 9,300 miles between their Arctic breeding territory and wintering grounds in South America. Their nonstop flights of 2,000 to 4,500 miles are aided by atmospheric conditions at high altitudes.
Conservation Status
Lesser Yellowlegs have an extensive breeding range estimated at over 4 million square kilometers. Their global population is estimated at 1.5 to 2 million birds. Partners in Flight estimates their population is stable overall.
Lesser Yellowlegs are not considered globally threatened, with a conservation status listed as Least Concern by the IUCN Red List. However, habitat loss and degradation on their migration routes and wintering areas is an ongoing concern. Pollution and disturbance also threaten key coastal wetlands relied upon by Lesser Yellowlegs.
Interesting Facts
- Lesser Yellowlegs make loud “twee” alarm calls when disturbed.
- They get their common name from their bright yellow legs.
- Their scientific name Tringa flavipes means “yellow-footed Tringa”, referring to their yellow legs.
- Lesser Yellowlegs sometimes move in a circle to stir up prey while foraging, a behavior called “foot trembling.”
- They migrate in flocks of up to several hundred birds.
- Lesser Yellowlegs breed farther north than any other shorebird in North America.
- They can dive briefly underwater to escape predators or capture prey.
- Their eggs are pointed at one end to help them roll in a circle around the nest if disturbed.
Conclusion
In summary, the Lesser Yellowlegs is an elegant, long-distance migratory shorebird known for its bright yellow legs and small size. Key characteristics include their gray and white barred plumage, medium-length bill used for probing, and shrill flight calls. They breed in subarctic wetlands and winter along southern coasts. Lesser Yellowlegs forage agilely for aquatic invertebrates in shallow waters across a variety of wetland habitats. Their populations appear stable, though habitat loss is an ongoing threat. The Lesser Yellowlegs’ graceful movements and far-ranging migrations make them a treasured part of the biodiversity of the Americas.