Chlidonias leucopterus

White-winged Tern

Family: Laridae · Class: Aves · Order: Charadriiformes

The White-winged Tern is a small to medium-sized tern measuring 20 to 23 centimeters (7.9 to 9.1 inches) in length with a wingspan of 64 to 67 centimeters (25 to 26 inches). Adults in breeding plumage display distinctive black head and body contrasting sharply with white wing coverts and rump. The wings appear predominantly white from above, giving the species its common name. Non-breeding adults show a pale gray back and white underparts with a dark ear patch and partial black cap. The bill is black and relatively short compared to other terns, while the legs are dark red to black. Juveniles resemble non-breeding adults but with brownish markings on the back and wings. The White-winged Tern breeds across a vast range from Eastern Europe through Central Asia to Mongolia and northern China. In North America, this species is considered a vagrant, with scattered records along both Atlantic and Pacific coasts. California records are extremely rare, with fewer than ten documented occurrences since the mid-20th century. Most California sightings have occurred along the coast during fall migration, primarily in the Salton Sea region and coastal areas from San Diego to Humboldt counties. This species typically inhabits freshwater and brackish wetlands during the breeding season, including shallow lakes, marshes, flooded meadows, and rice fields. White-winged Terns prefer areas with extensive emergent vegetation such as cattails and sedges. During migration and winter, they utilize coastal lagoons, estuaries, and offshore waters. In California, vagrant individuals have been observed in various wetland habitats including sewage treatment ponds, coastal mudflats, and inland lakes. White-winged Terns are highly aerial, spending considerable time foraging over water surfaces. Their diet consists primarily of aquatic insects, small fish, crustaceans, and amphibians. They employ various feeding techniques including surface dipping, shallow diving, and hawking insects from the air. The species is colonial during breeding, with pairs constructing floating nests of plant material anchored to emergent vegetation. Females typically lay 2 to 3 olive-brown eggs with dark markings. Incubation lasts approximately 18 to 22 days, with both parents sharing duties. The White-winged Tern is not federally listed in the United States, as it is not a regular breeding species in North America. Globally, the species is classified as Least Concern by the International Union for Conservation of Nature, with stable populations across its primary range. However, some regional populations face threats from wetland drainage, agricultural intensification, and climate change. The species' rarity in California makes it of special interest to birders and researchers studying vagrant patterns. Each California occurrence provides valuable data on long-distance dispersal and potential range expansion patterns. Climate change may influence future vagrancy patterns, potentially affecting the frequency of White-winged Tern observations along the Pacific Coast.

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, and more.