Bonaparte's
Gull, Larus
philadelphia
Bonaparte's are handsome small gulls that become adults in two years. They are tern-like in appearance, flight, and feeding behavior, often fluttering over water daintily picking food off the surface. Above, an adult on its nesting grounds in Alaska in late May; below, a bird in April, with a few remaining winter light feathers in its hood as it molts into breeding plumage.
Above, a Bonaparte's adult in full breeding plumage in California on May 1; below, two pictures of a flying breeding-plumage bird in Alaska in late May.
Above, adult non-breeding plumage.
This ratty-looking bird is molting out of the brown juvenal plumage into the gray adult-type feathers of first winter plumage.
The dark bar between the back and the flanks marks the bird as first winter; that same bar is the inward slanting arm of the conspicuous "M" visible on the upperparts of a first-winter Bonaparte's Gull.
The dark terminal bar on the tail, seen above and below, marks these birds as first-winter.
An all-white tail, seen in the bird above and those below, indicate an adult in non-breeding plumage.
