Bonaparte's Gull (Larus philadelphia)

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A Field Guide to Eastern Birds. by Roger Tory Peterson.

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Adult Summer Plumage

Immature

Adult Winter Plumage

Color Photographs: © by and courtesy of John Cassady

Bonaparte's Gull (Larus philadelphia)

Identification: Length from tip of bill to tip of tail 12 to 14 inches.

Adult Summer Plumage: Head black with a white eye ring. Bill black. Neck, back, breast, and underside white. Wings light gray except for an apical wedge of white feathers. White wedge not continued in a narrow band along the forward edge of the wing. Large outer wing feathers tipped with black. Tail white.

Adult Winter Plumage: Similar to the Summer Plumage, but head white with a brown spot below and behind the eye.

Immature: Head white with a brown spot behind and below the eye. Wing light gray with a brownish band running from the rear base of the wing to the wrist. Trail edge of inner half of wing brownish.. White apical wedge streaked with black. Tail white with a apical black band.

Similar Species:  There are several species of gulls with black heads in their adult, summer plumage. These species are best identified by the configuration of colors on the wings. The Laughing Gull has an entirely gray wing with a narrow, white, rear margin. The wings tend to shade to black toward the apex. Franklin's Gull has gray wings with a black band bordered by white both before and behind. The large apical feathers are not tipped with black. Sabine's Gull has a black outer, forward wing patch, and inner, white rear margin, and a pale gray inner, forward margin. The entire forward wing margin of the Black-headed Gull is white and the bill is red, not black. The rest of the wing is light gray. The tips of the primary feathers are black. Finally the Little Gull is smaller than these other species. The entire wing is light gray and the rear margin with white. The immature Franklin's Gull is most similar to that of the Laughing Gull. However the head of the Laughing Gull is all brown, not white with diffuse gray markings.

Breeding Range (see map below): Bonaparte's Gull is an inland species during the breeding season breeding in the taiga regions of Canada and Alaska from Hudson's Bay in the east westward to Alaska.

Overwintering Range:  This species overwinters along the coastal regions of the United States and around the Great Lakes.

Habitat: Bonaparte's Gull is found near lakes and rivers surrounded by forest during the breeding season. Overwintering individuals are found along the coast and in estuaries and bays.

Food: Aquatic invertebrates, garbage and carrion, and small fish.

Behavior: Bonaparte's Gull tends to keep to itself and is not associated with groups of other gull species. The flight is light and airy, almost tern-like. The voice is a harsh tea-ar.

Reproduction:  The clutch consists of spotted olive-green to tan eggs. The eggs are laid in a nest lined with twigs, grass, and moss. The nest is most commonly placed in a fir or spruce tree near a lake or river.