Bonaparte's Gull


Common Name:Bonaparte's Gull





SpeciesLarus philadelphia

Photo: Kyle Horton



Bonaparte's Gulls are in the order Charadriiformes which consists of gulls, terns, alcids and sandpipers. They are in the family Laridae which groups them together with Gulls. These gulls are very petite, almost tern-like as they are 13.5 inches (34 cm) in size with a 33 inch (84 cm) wingspan. Bonaparte's Gulls are not sexualy dimorphic which means that both sexes look alike. Adults have a black head during the breeding season and black ear patches during the winter season. They have white crescents above and below their eye.

Their breast, neck, belly and tail are all very white and they have a pale gray back and upper wings. Their primaries also have black tips that create a black trailing edge when they are flying and black wingtips when they are at rest. Bonaparte's Gulls take 2 years to become adults. At first they appear to be brown which will rapidly fade away. A juvenile's head and body will look like an adult's during the winter season. They will have a white tail with a black band at the end.


These gulls spend the breeding season in Alaska and western and central Canada. During the winter months, Bonaparte's Gulls are found in southern United States, parts of Mexico and Cuba. During a mild winter they can be found around the Great Lakes. Bonaparte's Gulls prefer being near water in places such as: ocean bays, coastal waters, sewage outlets, wet meadows and mudflats. The diet of Bonaparte's Gulls consists mostly of terrestrial invertebrates, though they will eat aquatic invertebrates as well. During migration they will eat mostly fish, shrimp and other crustaceans. When foraging, they take items from the surface of the water or just below while floating or swimming in the water. When they are foraging for fish they will drop from a high height in the air to the water.



Not much is known about the breeding biology of Bonaparte's Gulls. They are believed to be monogamous with one brood per year. It is thought that both the male and female will construct the nest which is usually located in abandoned tree nests. They place the nest on a branch close to the trunk of the tree or sometimes it is near the ground. The female will lay about 3 buff eggs that are marked with brown. It is believed that both sexes incubate the eggs for the 24 day period. The development of the young is semiprecocial which means they are mobile, fed and remain at the nest. Both parents will care for the young until they are ready to fledge.




Bonaparte's Gulls can be seen on the Niagara River and around Lake Erie during temperate winters in Buffalo.


Photo: Kyle Horton


Birds of Western New York is brought to you by the Institute for the Study of Human-Animal Relations at Canisius College in Buffalo, NY.