Bonaparte's Gull

Bonaparte's Gull is one of the smallest and most graceful gulls in North America, with a light, buoyant, almost tern-like flight. In breeding plumage it has a neat black hood, pale gray back and wings, white underparts, and a slender black bill, quite different from the heavier red or yellow bills of most other gulls.

One of its most striking features in flight is the white wedge on the leading edge of the outer primaries, which flashes conspicuously as the bird wheels and dips over water. Legs are orange-red, another distinctive feature among small gulls. In non-breeding plumage the black hood is replaced by a white head with a small, neat black spot behind the eye.

Unusually for a gull, Bonaparte's Gull nests in coniferous trees near water rather than on the ground or in dense colonies, a habit shared by very few other gull species worldwide.

Key field marks

• Small size and light, tern-like flight
• Thin black bill (breeding and non-breeding)
• Black hood in breeding plumage; small black ear spot in winter
• White wedge on the leading edge of the outer wing, conspicuous in flight
• Orange-red legs

Similar species

• Little Gull: even smaller, with a dark underwing and rounder wings, lacking the white leading-edge wedge.
• Black-headed Gull: larger, with a red bill and legs and a browner hood when breeding.
• Laughing and Franklin's Gulls: notably larger and stockier, with red or dark bills and different wingtip patterns.

Habitat

Breeding habitat is boreal forest with scattered spruce or larch near shallow lakes, ponds, and muskeg bogs. In migration and winter, Bonaparte's Gulls favor coastal bays, harbors, estuaries, and large inland lakes and rivers.

Range and migration

It breeds across the boreal forest of Alaska and Canada and winters along both the Atlantic and Pacific coasts of North America, south to Mexico, as well as on the Great Lakes and other large inland waters during migration.

Behavior

Bonaparte's Gulls are agile fliers, often feeding in loose flocks by picking prey directly from the water's surface or making short plunge-dives, sometimes associating with feeding whales, fish schools, or terns.

Voice

Calls include a soft, nasal, tern-like "cheer" or rasping note, quieter than the calls of larger gulls.

Feeding

Diet consists mainly of small fish and aquatic invertebrates, along with flying insects caught on the wing during the breeding season.

Nesting and breeding

Unusually among gulls, Bonaparte's Gull builds a stick nest in a conifer tree, typically a few meters above the ground near water, rather than nesting on open ground. Clutches usually contain two to four eggs, incubated by both parents.