Egg fertility among vasectomized and non-vasectomized male resident Canadageese at the Wildlife Conservation Park Bronx Zoo

In 1991, a vasectomy program was initiated at the Wildlife Conservation Par k/ Bronx Zoo to minimize the population growth of resident Canada geese (Br anta canadensis). Sixty-nine males were vasectomized over a 6-year period. From 1994 to 1998, egg fertility was examined in females paired with vasect omized and non-vasectomized geese. Of the 340 eggs laid by females paired w ith vasectomized males, 12% were fertile. In comparsion, of the 526 eggs la id by females paired with non-vasectomized males, 90% were fertile. The vas ectomy procedure was easier to perform on males captured during the breedin g season than on those captured during molt owing to the enlarged size of t he vas deferens. Where resident Canada goose populations are small and reso urces available, the implementation of a vasectomy program can be effective in reducing population growth. (C) 2000 Wiley-Liss, Inc.