(Note from Miles: I was able to photograph this bird near Geraldton in June 2018)
Bonaparte’s Gull is by far the most numerous of the pigeon-sized gulls to be found in Ontario. It nests in trees in northern Ontario.
In migration large flocks may be found along the shores and harbours of the larger bodies of water in southern Ontario.
Some linger along the north shore of Lake Erie until freezeup and well into the winter along the Niagara River, but most migrate south to the Gulf of Mexico.
Most black hooded gulls seen in Ontario are this species. After the breeding season the black hood is lost and replaced by “dirty ear” patches.
In either plumage Bonaparte’s Gulls can be identifies almost as far as they can be seen in flight by the white flash in the leading edge of the wing.
(The Black-headed Gull also shows this white leading edge but is seldom seen in Ontario and never in large flocks).
Dr J Murray Speirs