Wetland selection by Eared Grebes, Podiceps nigricollis, in Minnesota
Canadian Field-Naturalist 106(4): 480-488
In 1986, 1 studied wetland selection by Eared Grebes (Podiceps nigricollis) in Minnesota by comparing a group of wetlands used for breeding by grebes (n = 23) to a stratified random sample of unused wetlands (n = 26) in the same or nearby counties. Incidental observations made during the 1987-1989 field seasons pertinent to wetland selection are also included. Eared Grebes showed a preference for Type 4 wetlands that were gt 30 ha in size and that contained 42-100% ( hivin x = 78%) open water. Used wetlands were shallower and had more submergent vegetation and less treed perimeter than did unused wetlands. They were also less likely to have a public access than were unused wetlands, and they received less human use in the summer. In the drought of 1988, grebes left small wetlands and formed larger-than-usual breeding colonies on large wetlands. In 1989, two colonies were found on wetlands that were recently reflooded following managed drawdowns. Eared Grebes regularly occur, and sometimes nest, on sewage lagoons and on the most alkaline wetland in the state. The maintenance of wetland quantity, diversity, and dynamism is important to the continued reproductive success of Eared Grebes in Minnesota.