Demographics of Canada geese introduced in western Colorado

Abstract

Breeding populations of Canada geese (Branta canadensis) were established throughout western Colorado during 1955–1988 using geese transplanted from other areas. Subsequently, there has been no assessment of demographics and winter distributions on these local populations. Managers need this information to effectively manage breeding populations of Canada geese to provide publics with recreational opportunities and to reduce human-goose conflicts in western Colorado, particularly for segments of internationally recognized populations with cooperative management plans. We conducted a band recovery study during 2000–2006 to assess demographics and winter distributions of Canada geese breeding in 7 subareas of western Colorado. Cooperators banded 19,189 geese during June and early July. We recaptured 5,185 of these geese 1–4 times during banding operations in subsequent years and most (97%) were recaptured in the subarea of banding the year after banding. We obtained 2,921 useable band recoveries through May 2007, and most (98%) recoveries were a result of either being shot or found dead during hunting season. Direct band recoveries (<1 year after banding) were recovered almost exclusively in Colorado (87%) and New Mexico (12%), and indirect band recoveries (≥1 year after banding) showed similar distribution (73% in Colorado and 16% in New Mexico). Geese in subareas of western Colorado had different recovery distributions, and contributed to 4 wintering concentrations of Canada geese in western and central Colorado and New Mexico. Annual survival probability for adult geese was 0.864 ± 0.012. The survival probability for juvenile geese was 0.503 ± 0.026, but we did find evidence that this estimate may be biased low. We used the band reporting probability of 0.525 ± 0.071 to derive harvest rates from band recovery rates. Harvest rate was 0.128 ± 0.018 for adult geese and 0.169 ± 0.024 for juvenile geese. Survival probability was lesser and harvest rate greater for the 3 western subareas (Western Plateau) compared to the 4 eastern subareas (Rocky Mountains). Our results suggest that Canada geese that breed and molt in western Colorado have high survival probability and are largely non-migratory with some movement in winter from high to low elevation areas primarily in Colorado. To effectively manage the growing resident goose population in western Colorado, managers may need to increase harvest rates for these geese. © 2014 The Wildlife Society.