One of the greatest courtship spectacles in the world of birds can be observed every spring on Lake Osakis: the barging displays of mated pairs of Western Grebes. The birds rush across the surface of the water for up to 20 meters before diving. The lake has excellent habitat not only for Western Grebes but also for a few Clark’s Grebes, which are at the eastern limit of their range. Other species to watch for in spring include Red-necked, Eared, and Horned Grebes, Forster’s and Black Terns, American White Pelicans, and Common Loons.
From mid-August through early September, another avian spectacle occurs at the south end of the lake. Every evening at sunset, more than 50,000 Purple Martins swarm over the lake and settle into the emergent vegetation to roost overnight. While waiting for the martins to appear, watch for Western and Clark’s Grebes, Franklin’s Gulls, and a few Bonaparte’s Gulls. Late summer is also a good time to scan shallow wetlands or flooded fields for migrating Marbled Godwit, Wilson’s Phalarope, and other shorebirds. — Carrol Henderson
Carrol Henderson is the nongame wildlife program supervisor for the Minnesota Department of Natural Resources and the author of many books about birds. He wrote about Agassiz National Wildlife Refuge in our June 2007 issue.