In April, Goose Pond Sanctuary serves as a migratory stopover for Bonaparte’s gulls, the smallest gull usually seen over most of North America.
Delicate in flight, it suggests a tern more than it does the larger gulls. Bonaparte’s are easy to identify with their black head during the breeding season.
They differ from large gulls in other ways as well: it seldom scavenges in garbage dumps, and it nests in trees on the ground. The name honors French zoologist Charles Lucien Bonaparte, a distant cousin of Napoleon who made important contributions to American ornithology while an active member of the Academy of Natural Sciences of Philadelphia during the 1820s.
Bonaparte’s are heading north to the boreal forest after wintering in the gulf coast. Sam Robbins in his 1990 Wisconsin Birdlife listed Bonaparte’s gulls as an uncommon migrant in southern Wisconsin. Before 1890’s, this gull was an abundant spring migrant at Lake Koshkonong. Kumlien and Holliser wrote in 1903 that “The systematic slaughter of this beautiful gull for millinery purposes has so reduced its numbers that we can no longer claim it as our most abundant species.” They mentioned how plume-hunters from Chicago would shoot these birds by the hundreds in southeast Wisconsin. We wonder if the plume hunters visited Goose Pond.
Sam reported by the 1980’s that small numbers can be found on inland lakes with larger numbers on the Great Lakes. We see Bonaparte’s gulls every year and flocks frequently number in the hundreds.
Mark and Brand Smith counted 255 Bonaparte’s on April 21 at Goose Pond while conducting a waterfowl count. Most of the gulls were resting on the shoreline of the east pond. They forage in flight by plunging into the water or dipping to the surface; also picks up items while swimming or wading. At Goose Pond they forage on fathead minnows. During the breeding season they frequently forage on insects that they catch on the wing.
It is interesting that they nest in isolated pairs or small colonies in conifer (spruce) stands. The nest is reported to usually be a small platform or open cup of sticks, lined with finer materials such as grass and moss.
We are glad that the numbers of Bonaparte's Gull have increased over last 100 years. Hopefully you can visit Goose Pond before they head north around the end of April.
By Mark and Sue Foote-Martin, Resident Managers, Goose Pond Sanctuary