Migration and population dynamics of American coots in western North America
Ryder, R.A.
Proceedings Internatl Ornithol Congress 13: 441-453
1963
Document Number: 403717
Based upon an analysis of 4,721 recoveries of banded coots, it appears that Fulica americana migrates southward over a variety of routes more or less on a broad front. Coots that breed in the eastern prairie provinces of Canada and plains states winter largely in Louisiana and eastern Mexico, whereas those from more western nesting grounds winter mainly in California and western Mexico. Apparently, coots from more southern nesting regions are likely to winter as far south as Central American and the Caribbean. Mean and annual mortality rates were computed as follows: 55% for all age samples, 61% for coots banded as adults, and 83% for those banded before their 1st migration. The latter birds experience 1st-year mortality of 87-88%, and 60-65% in years thereafter. Although somewhat biased too low, these rates are somewhat higher than those for most dabbling ducks (Anatinae). A dynamic population model based on statistics assumed to represent current norms suggests that the population is now slowly declining.