Age and Sex Criteria and Weights of Canada Geese

Abstract

A total of 2,179 Canada geese, Branta c. canadensis, shot by hunters and live-trapped in banding studies at Horse Shoe lake, Alexander Co., Illinois, were weighed and examined in testing the reliability of criteria for age and sex detn. The max. wt. was obtained by a [male] of 11 lbs., 9 oz. Only 6 birds exceeded 10 lbs.; all were [male][male] cf. The average wt. of juvenile [male][male] was 6.5 lbs., of adult [male][male] 7.01 lbs., of juvenile [male][male] 7.5 lbs., and of adult [male][male] 8.4 lbs. The differences between the wt. of juvenile and adult geese of each sex and the wts. of [male][male] and [female][female] at any age were significant. The wt. loss during the winter was significant in all groups. The best criterion for distinguishing the juvenile bird is the notch in the tips of the rectrices. The dull brownish cast of these feathers as well as of the remiges is distinct from the glossy black of the adult. Molt of the rectrices is centrifugal and in juvenile birds it continues through the winter. Pigmentation of the cloaca, ureteral papillae, penis and clitoris increases with age. This gradual change as well as the gradual increase in size of the penis, the slow resorption of the bursa of Fabricius and occluding oviducal membrane, all indicate that sexual maturity in wild Canada geese is not reached until the 3d or 4th year of life.