Belcher's gull, also known as the band-tailed gull, is a bird in the family Laridae found along the Pacific coast of South America. It formerly included the very similar Olrog's gull as a subspecies, but that bird occurs on the Atlantic coast of South America and is now accepted as Larus atlanticus. Belcher's gull is a medium-sized gull with a blackish mantle, white head and underparts, a black band on the otherwise white tail, and a yellow bill with a red and black tip. Non-breeding adults have a brownish-black head and a white eye-ring. The name of this bird commemorates the British explorer Sir Edward Belcher, who performed survey work on the Pacific coast of South America.
Region
Pacific coast of South America
Typical Environment
Found mainly along the Peruvian coast and north Chile, with occasional records into southwest Ecuador. It frequents rocky and sandy shores, guano islands, breakwaters, estuaries, and harbor areas. The species is highly tied to the productive Humboldt Current, often gathering where fishing activity and upwelling concentrate food. Breeding typically occurs on coastal islands and islets, using open ground or low vegetation.
Altitude Range
Sea level to 200 m
Climate Zone
Arid
Ease of Keeping
Beginner friendly: 1/5
Belcher's gull, or band-tailed gull, inhabits the Pacific coast of South America, especially along the cold Humboldt Current. It was once lumped with the very similar Olrog's gull, which is now recognized as Larus atlanticus on the Atlantic side. The broad black band near the tip of its otherwise white tail is a distinctive field mark, as is the yellow bill with red and black on the tip. It readily scavenges around fishing ports and markets and often follows boats.
The band on the tail is a diagnostic feature.
Foraging on the beach in Peru
Adult and immature Belcher's gulls, Callao, Peru
Temperament
social and opportunistic
Flight Pattern
strong flier with steady wingbeats; capable of leisurely soaring in coastal winds
Social Behavior
Often forms loose flocks along beaches and ports and breeds colonially on coastal islands or man-made structures. Nests are shallow scrapes lined with vegetation or debris, typically with 2–3 eggs. Pairs are seasonally monogamous and defend small territories around the nest.
Migratory Pattern
Resident
Song Description
Vocalizations are typical gull-like, with loud, raucous yelps and ke-yah calls, especially at colonies. Also gives rapid kek-kek alarm notes and harsh scolding calls when defending food or nest sites.
Plumage
Breeding adults show a blackish-slate mantle with white head, neck, and underparts; tail is white with a broad black subterminal band. Non-breeding adults develop a dusky to brownish-black hood and a distinct white eye-ring. Primaries are blackish with pale tips, giving a crisp contrast to the upperwing.
Diet
Takes small fish, crustaceans, mollusks, and marine invertebrates, and will scavenge carrion and fish offal. Frequently follows fishing boats and patrols fish markets and harbor edges for scraps. Will also raid eggs or chicks of other seabirds and occasionally kleptoparasitize other gulls or terns.
Preferred Environment
Forages in the surf and intertidal zone, on rocky platforms, mudflats, and sandy beaches. Common around piers, breakwaters, and harbors where discards are available.
