Bonaparte's Gull

Utah Winter Gulls

by Dennis Shirley

     Bonaparte's Gull (similar species)

Breeding Adult - thin eye crescents, small black bill (in all plumages),
little white in the primaries, red legs (not shown)
Photo by Kendall Brown ©Kendall W. Brown

Non-breeding Adult - white head with gray hindcrown and ear spot,
long wedge of white on outer wing
by Lu Giddings ©Lu Giddings

First Winter - narrow black tail band, black trailing edge of wing with small white tips
on all but outer 2 primaries, large wedge of white in primaries, flesh-colored legs
by Paul Higgins ©Paul Higgins

Bonaparte's Gull

Similar Species

Franklin's Gull - is larger, with a darker mantle. Adults have a white wing bar inside the black wing tips. Immature Franklin's have larger bill, and are lighter and more spotted beneath; have a more distinct wing and tail pattern.

Little Gull - has a much smaller bill; has black, not white, eye crescents; has a much more distinctive cap on the back of the head in winter plumage. Adult Bonaparte's underwing is white rather than black; Immature has a black trailing edge on the wing, narrowly tipped with white, and lacks blackish cap.

Black-headed Gull (not in Utah) - Bonaparte's Gull is obviously smaller; has white underwing narrowly bordered with black (only primaries on adults; entire tailing edge in immatures); smaller bill is all or mostly black. Breeding adult Bonaparte's has more prominent white eye crescents. Immatures upperwing has black edges on outer primary coverts, a narrow, neat, black trailing edge with most primaires and secondaries showing white tips with new plumage.

Adult Franklin's - has a white bar across the wing tips
and has gray in the middle of the tail.
Photo by Margaret T. Sanchez ©Margaret T. Sanchez

Non-breeding Little Gull (on left) - is obviously much smaller, has a relatively smaller bill,
has black not white eye crescents, and has a small black cap on its head.
Photo by Jack Binch ©Jack Binch

Bonaparte's Gulls - have pointed wings and a black trailing edge of the wing unlike Little Gulls.
Photo by Kendall Brown ©Kendall W. Brown