Nest Success of Giant Canada Geese in Southern Illinois‪.‬

ABSTRACT Giant Canada Geese (Branta canadensis maxima) were released by the Illinois Department of Conservation (IDOC) in west-central Illinois in the late 1960's and in southern Illinois in the mid-1980's in an effort to re-establish resident flocks of Canada geese in Illinois for their aesthetic value and harvest potential. Illinois Department of Natural Resources Giant Canada Goose surveys, however, indicate a density three times greater in the northern 2/3 of the state than in the southern 1/3 of the state. To determine if variation in nest success explains the difference in Giant Canada Goose nesting density between northern and southern Illinois, we estimated nest success of geese nesting in various wetland habitat types in southern Illinois, then compared those estimates to estimates from other studies conducted in central and northern Illinois. In 2003, 181 nests were located and in 2004, 221 nests were located providing 402 total nests for the study. The most parsimonious model included a covariate of clutch initiation date and habitat type, but daily nest survival was held constant between years, and among days of the breeding season, and locations. Nest success for a nest initiated on the mean initiation date over all study sites and years combined was estimated to be 61% (SE = 4.8%). Nest success in our study was greater than or equal to estimates of nest success in other regions of Illinois indicating variation in nest success is not leading to lower population densities of Giant Canada Geese in southern Illinois.