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Bonaparte's Gull (Chroicocephalus philadelphia)


Older books place this species, whose primary range is confined to North America, in the “catch-all” genus “Larus” in company with many other species of gulls, but in 2008 it was found to be part of a genetically distinct group with other, mostly “hooded”, gulls, and placed with them in the genus Chroicocephalus, a move first suggested in 1858. The adults are similar in appearance and molt the dark hoods out in winter, although often retaining them quite late into the season. Young and winter birds have light colored heads with dark splotches on the sides of the head.

The Bonaparte for whom they were named was French-born ornithologist Charles Lucien Bonaparte, nephew of Napoleon, and an important and honored 19th century figure in both American and European-British ornithology. The genus name is derived from the Ancient Greek, khroizo, “to color” and kephale, “head”.





The first specimen known to science happened to be from Philadelphia, Pennsylvania, in 1815, but we now know the species breeds in boreal forests from Alaska across Canada into Quebec, and migrates south as far as the southern U.S., Mexico and the West Indies, and only migrates through Philadelphia, and many other cities in every one of the 48 contiguous states.


These small (180 t- 225 grams, or about 6.3 to 7.9 oz), rather dainty, tern-like gulls are very common, yet easily overlooked because they don’t share the habits of larger gulls who forage around dumps and fast-food outlets, thus coming into close contact with people. An excellent place to see Bonaparte’s Gulls is not too far from where I live: the mouth of the Niagara River (and the whole Niagara Gorge) from November into December, when tens of thousands may be seen swarming in a “gull blizzard” where the river reaches Lake Ontario. In winter they occur up most of the Mississippi River and around the temperate coastlines of North America, Mexico, and the northern West Indies. A very few arrive in the U.K. or Europe, each year.

They are the only gulls that nest in trees, in loosely formed colonies, the nests being platforms of twigs and other vegetative materials constructed by both sexes, who appear to be monogamous, and who fiercely defend the nest against predators – and people. Nests are typically in open boreal forest or bogs, near water, well up in trees (the odd one on

the ground).


Two to four eggs are laid. The parents take turns incubating. I worry about the impact of this year’s fire season on these and other boreal birds, not just directly from the fires, but also from smoke pollution as birds’ lungs are susceptible to dangerous atmospheric conditions, which is why, historically, caged canaries were used to detect toxic gasses in mines before there was serious threat to the miners.

Bonaparte’s Gulls eat mostly invertebrates, small fish and other aquatic organisms, eggs and hatchlings of fish and other marine life that they may dive underwater to obtain. They consume numerous insects, often fly-catching in aerial chases into swarms of dispersing insects such as Mayflies, midges, and termites. They sometimes take food from smaller shorebirds, a practice called kleptoparasitism. They rarely eat vegetative food or visit landfills, but they do frequent shoreline sewage outflows, especially at low tide. They are deft in plucking food off the surface of water. In flight they show narrow, white, black-tipped triangular wing patches on the primary (outermost) feathers, that add to their attractiveness.

The painting is in oils on compressed hardboard (Masonite®) and is 24 by 18 inches. It was inspired when I was sketching some birds late in the fall and noticed how hooded the head of a bird still mostly in summer plumage looked when viewed from directly behind, the head wider than the top of the neck, and how mixed the plumages were. I wanted, too, to show how high they sit in the water, very buoyant. The painting is approximately life size. I’ve also included a small, watercolour and pencil sketch of the Bonaparte’s Gull I did from life some years ago.


Barry Kent MacKay

Bird Artist, Illustrator

Studio: (905) 472 9731

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