Papers in the Biological Sciences


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Published in Johnsgard in American Midland Naturalist (October 1961) 66(2). Copyright 1961, University of Notre Dame. Used by permission.


Through the use of data compiled by the Audubon Society's annual Christmas Counts, an attempt has been made to trace the distributional changes of wintering Mallards and Black Ducks in the eastern states from 1900 to the present. During this period the Black Duck has increased relative to the Mallard in few if any states (the Great Lakes region), whereas the Mallard has increased nearly everywhere else (except in the extreme northeast), particularly in the southern coastal states. Deforestation and changes in land use are sug- gested as probable reasons for this trend, which is not likely to be reversed.

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