General

Bonaparte's Gull: Medium gull with black head and bill, gray back, and white underparts and tail. White outer primaries with black trailing edges are visible in flight. Legs are red-orange. Sexes are similar. Winter adult lacks black hood but has dark spot behind eye; legs are pink. Juvenile is resembles winter adult but has brown-washed back, nape and crown, and black-tipped tail.

Range and Habitat

Bonaparte's Gull: Breeds across northern North America from western Alaska to Hudson Bay. Spends winters along Atlantic and Pacific coasts and Gulf of Mexico. Preferred habitats include large lakes, rivers, and marshlands.

Breeding and Nesting

Bonaparte's Gull: Two to four brown blotched, olive to buff eggs are laid in a nest made of sticks and twigs, lined with grass and moss, and built near or over water; typically builds nest in a tree rather than on the ground. Both parents incubate eggs for 24 days.

Foraging and Feeding

Bonaparte's Gull: Feeds mostly on insects picked from the water surface or rotting vegetation along shorelines during breeding season. Diet shifts to small fish, crustaceans, marine worms, and other invertebrates in winter. Forages by picking food from the water surface while swimming or flying with dangling feet; also makes shallow plunge dives.

Vocalization

Bonaparte's Gull: Utters shrieking whistles and a call of "cheer."

Similar Species

Bonaparte's Gull: Black-headed Gull has pale bill and dark primary undersides.