With their primary breeding grounds inprairie Manitoba, the eastern continental population of canvasbacks stagedduring the fall in the olden days on Lake Cristina and Heron Lake in Minnesota;the Detroit River, Lake St. Clair and Saginaw Bay in Michigan; the IllinoisRiver in Illinois, in Iowa along the Upper Mississippi, and Lakes Poygan, Puckaway, Butte des Morts, Winnebago, Winneconne, and Koshkonong in Wisconsin. Lake Koshkonong was the countless hosts of migratory waterfowl which knew it from a time before a white man ever gazed upon its waters.

From its beginning, the Koshkonong marsh wascovered with from one to two feet of water and filled entirely with wild riceand in a few deep-water places wild celery grew. During the fall and springmigration, the marsh was literally alive with mallards, teal, and otherdabbling ducks with a few canvasbacks and redheads in a few deeper areas. Thenthe dam in 1851 was built which raised the water level enticing more wildcelery to grow and year after year it grew more and the canvasbacks came ingreat numbers. Then the dam was made higher in 1874, which raised the level ofwater even higher and once again more wild celery grew while the wild ricereceded closer to the shore. Then the canvasbacks came in greater number whichwas beyond computation and the mallards departed for the most part to thesurrounding marshes boarding on the sides of the lake. Furthermore, during summer,thousands of young canvasbacks could be seen as the result of the breedingseason unconscious of the fate that awaited them within a few months from thehands of sportsmen and market hunters.

But all of this changed with theoverharvesting of canvasbacks, the introduction of carp, the extended raisingof the dam, the onset of WWI, the Dust Bowl Years, pollution, the drainage ofthe numerous marshes which existed outside of the boundary of the lake and thedrainage of other small wetlands near the lake along with their ancient hangoutson the lake being covered with the dwellings of the white man which added extrahunting pressure on waterfowl using the lake and increased use of the lake forleisure motorboating which ran many waterfowl off the lake.