NECK COLLAR RETENTION IN DUSKY CANADA GEESE

A total of 4965 Dusky Canada Geese (Branta canadensis occidentalis) were neck-collared on the Copper River Delta, Alaska, in 1984-1990. Collar retention rates for adult geese were obtained from examination of 910 recaptures. The effects of sex, collar age and collaring year on retention rates were determined using logit models. As there was a significant interaction between the effects of sex and collar age on retention rates, the sexes were modeled separately. The average annual retention rate for female geese (0.875 +/- 0.163 SE) was independent of all effects considered. Retention rates for males was influenced by collar age and the year collared. It is concluded that collar losses were substantial and that losses specific to the years modeled should be considered in any population model.