Bonaparte’s Gull

Chroicocephalus philadelphia

Compiled by Niyati Acharya

The species is named after Charles Lucien Bonaparte, a French ornithologist and nephew to the former French emperor Napoleon Bonaparte, who spent eight years in America contributing to the understanding of the taxonomy and nomenclature of birds there and elsewhere.

The Bonaparte’s gull is the most common small gull through most of North America, especially inland. Breeding adults have a black head, thin white eye arcs, bright red legs, light gray upperparts, and black wingtips.  A distinctive wing pattern on adults in flight is a white wedge on the leading edge of the wing, with small black tips on the outer wing feathers.  Nonbreeding adults and immatures have pinkish legs and a mostly white head with a black ear spot.  Immatures are more heavily marked with brown and black on the wings.  The species breed near water in boreal forests, and is the only gull that makes a stick nest in a tree.  They are often seen in large flocks along beaches, bays, coves, and lakes during migration and winter.  The feed on small fish and invertebrates, often gracefully fluttering around and picking them off the water surface.

Bonaparte’s Gulls prefer larger lakes, but occur on smaller ponds, as well.  These gulls like to rest on the tops of boat lift canopies.  They are one of the smallest species of gulls, averaging 11 to 15 inches in length.  During breeding season, Bonaparte’s gulls gain a slaty-black hood.  The sexes are similar in appearance.  These gulls prefer to be on the treed edges of lakes, ponds, marshes, or islands. They typically nest within 200 feet of open water. 

Their heads bob as they feed on the surface of the water, and they seem to work together in flocks of 15-20 as they feed.  Like most gulls, Bonaparte’s gulls have a varied diet, with prey items changing over the course of the year and from year to year.  During the breeding season, they are largely insectivorous. During migration and into the winter, insects are first supplemented, then replaced by other food items, including fish, small crustaceans, mollusks, euphausiids, marine worms, and other invertebrates. 

Bonaparte’s gulls occur in Missouri during spring and fall migration and, less commonly, in winter.  Like other gulls, they look different during different life stages, and they have different seasonal plumage patterns.  Breeding adults have black heads. Other times, the head is white except for a smudgy black spot behind the eye.  Wing markings are also helpful for identification.

The call is a harsh, scratchy “cherrr,” or “kheh,” somewhat like a Forster’s tern but lower in pitch.

Sources include: Ebird.org, Mt.gov, Glenlakeassociation.org, Mdc.mo.gov, 

Photo credit:  Weimer, Mike, Menke, Dave/USFWS, Weimer, Mike, USFWS