Breeding Habitat:Wetland-open water
Nest Type:N/A
Migration Status:N/A
Nest Location:N/A
The breeding habitats of Eared Grebes are similar to its relatives, large marshes, shallow lakes, sewage ponds, and similar areas where permanent open water supports extensive stands of dense emergent vegetation. Breeding pairs are widely distributed in central and western North America north to southern Canada (AOU 1983), a range that has not markedly changed during historic times. While many nesting records pertain to isolated pairs, this species also regularly forms large colonies of 100-1000+ pairs on a single body of water (Stewart 1975). There are considerable annual fluctuations in the size of these nesting colonies, indicating that local populations may select different nesting locations each year in response to varying habitat conditions.
Eared Grebes are locally distributed along BBS routes in western and central North America, becoming locally plentiful wherever suitable nesting habitats are located along routes (Relative Abundance Map). Some records along the southern portion of this range could pertain to late migrants or non-breeders.
As is true for many wetland birds, Eared Grebes are relatively poorly represented along BBS routes and its trend estimates should be viewed with some caution. Additionally, their semi-colonial breeding behavior and irregular movements cause the counts to fluctuate considerably from year to year, and the appearance or disappearance of a single colony can dramatically alter the trends from a state/province or stratum. Hence, these trend estimates are relatively imprecise and may be strongly influenced by the trends from a small number of routes. The 1966-1994 BBS trend estimates are generally positive, with increases in Saskatchewan, two physiographic strata, the Western BBS Region, United States, and survey-wide (Trend List). The 1966-1979 trends are generally significant increases, but should be viewed with caution given the small sample sizes and relative imprecision of these estimates. After 1980, the population trends are mixed but include a decline in the Central BBS Region. No consistent geographic patterns are apparent in the trend map, only a mixture of increases and declines (Trend Map). The survey-wide indices have generally increased since the mid- 1970s (Survey-wide Annual Indices). Indices for states/provinces and strata are quite variable and imprecise, showing no consistent temporal patterns.
Given the potential biases in the BBS data, these positive trend estimates may not accurately reflect the actual trends of the continental population. Some habitat loss has occurred during recent decades (Tiner 1984), undoubtedly producing local declines in abundance. However, given its semi-colonial behavior and tendency to shift its breeding locations in response to habitat availability, its overall populations could still be fairly stable despite the habitat destruction as breeding pairs could congregate in larger colonies in the remaining wetlands.
American Ornithologists Union. 1983. Check-list of North American
birds, 6th ed. Allen Press, Lawrence, KS. 877 pp.
Stewart, R.E. 1975. Breeding birds of North Dakota. Harrison
Smith, Lund Press, Minneapolis, MN. 295 pp.
Tiner, R.W., Jr. 1984. Wetlands of the United States: current
status and recent trends. National Wetlands Inventory,
Washington, D.C. 59 pp.