Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Renovating Erickson-Percival Reservoir

There's this:

Loons return to northern forested lakes and rivers in the springtime, usually in April or early May. The breeding range includes Alaska and much of Canada south to portions of Washington, Idaho, Montana, North Dakota, Minnesota, Wisconsin, Michigan, New York, Vermont, New Hampshire, and Maine.

Breeding loons, like those radiomarked in this study, leave breeding areas in late October to early November.

Loons spend the winter season along the Atlantic, Pacific, and Gulf of Mexico coasts. Some loons winter on inland reservoirs.