Larus philadelphia breeds in western Canada and Alaska from July to October. Bonaparte's gulls migrate south to spend the winter on the Pacific coast from Vancouver Island to points southward. Some migrate southward as far as Panama. They sometimes occur as vagrants in in a number of European countries as well as Japan, Israel, and Morroco. (Peterson, 1980; UNEP World Conservation Monitoring Center, 2001)
Bonaparte's gulls are found in ocean bays, coastal waters, islands, and lakes. (Miklos, 1994)
Bonaparte's gulls are slate-gray headed with a very small black bill and bright orange-red legs and feet. They have a white terminal band on tail feathers and secondaries. In young birds, the wing has a dark-bordered appearance, with flashy white wing tips. Adults reach 43 to 53 cm in body length. (Pough 1953)
Bonaparte's gulls nest in loose colonies throughout most of Canada, from Manitoba to west-central Ontario and north to Alaska. They are the only gull species that nests almost exclusively in nests built in trees, rather than on the ground. They lay two to four eggs in nests built from twigs and moss in spruce or tamarack trees near water. The eggs are grayish to greenish brown, marked with dark brown and lilac and 4.8 by 3.3 cm on average. (Peterson, 1980)
Bonaparte's gulls fly buoyantly and ternlike, with the bill held down. They are very active on the wing. Along the coast, where they are more abundant in fall, they feed offshore over tide channels and rips and kelp beds. They feed largely by dipping to the surface of the water. However, occasionally they drop into the water, take a few deep strokes, then glide to the surface to flutter in one spot for a moment before taking off again (Reed 1915).
The vocalizations of Bonaparte's gulls can be described as a harsh high pitched see-whee and a low pitched kuk-kuk-kuk. They produce many conversational whistled notes when feeding.
Small fish, crustacea, snails and marine worms are staple foods of Larus philadelphia along the coast. However, inland in summer they feed chiefly on insects they capture in the air, pick from croplands, or gather from the surface of lakes or ponds. (Miklos 1994).
Bonaparte's gulls are beneficial to agriculture, destroying insect pests, grubs, and worms in the fields.
There are no adverse affects of Bonaparte's gulls on humans.
The global population of Bonaparte's gulls is estimated to be between 260,000 and 530,000. This number seems to be stable.
Bonaparte's gulls are named after a nephew of Napoleon, Charles Lucien Bonaparte, who was a leading ornithologist in the 1800's in America and Europe. (Miklos, 1994)
Sam Park (author), University of California, Irvine, Rudi Berkelhamer (editor), University of California, Irvine.
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
mainly lives in water that is not salty.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
makes seasonal movements between breeding and wintering grounds
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
uses sight to communicate
Burger, J., M. Gochfeld. 2002. Bonaparte's gull (Larus philadelphia). Pp. 1-24 in A Poole, F Gill, eds. The Birds of North America, Vol. 634. Philadelphia, PA: The Birds of North America, Inc.
Miklos, D. 1994. National Audubon Society Field Guide to North American Birds. New York: Alfred A. Knopf, inc..
Peterson, R. 1980. A Field Guide to the Birds. Boston: Houghton Mifflin Company.
Pough, R. 1953. All the Birds of Eastern and Central North America. New York: Doubleday & Company,inc..
Reed, C. 1915. The Bird Book. New York: Doubleday, page & Company.
UNEP World Conservation Monitoring Center, 2001. "Threatened and Endangered Species: Larus philadelphia" (On-line). Accessed 2 March 2001 at http://www.unep-wcmc.org/index.html?http://ims.wcmc.org.uk/isdb/Taxonomy/tax-species-result.cfm?Genus=Larus&Species=philadelphia~main.