Waterfowl Use of the Laurentian Great Lakes

Abstract

Literature on habitat and limiting factors of waterfowl in Great Lakes wetlands and deep water habitats is reviewed; more than 30 species of waterfowl use coastal habitats at some time during the year. Waterfowl use of the Great Lakes has declined dramatically from presettlement times; the obvious cause is human encroachment on coastal wetlands and destruction of river delta and embayed wetland complexes. Loss of wetland habitats from diking and filling above the average water level constitutes a permanent habitat loss, especially during high water cycles. The greatest number of species and individuals use 15 concentration areas during the spring and fall migratory periods when use by diving ducks, sea and stiff tailed ducks, and swans and geese predominates. Lesser numbers of species use the coastal wetlands for breeding. Large concentrations of dabbling ducks, primarily mallards ( Anas platyrhynchos) and American black ducks ( A. rubripes), and mergansers ( Mergus spp.) are found on ice-free areas during winter. Wetland habitats have become more favorable, due to human modifications, to dabbling duck species found in the prairie habitats of North America. Mallards have become the most numerous species breeding in coastal wetlands along with a concomitant decline in black ducks, which may be a consequence of introgression. Habitat modifications, degradation, and loss have great potential to affect existing waterfowl populations negatively and to point the way toward future research.