COLONY SIZE, AGE, AND SEX STRUCTURE

Response of beaver (Castor canadensis) to baited Conibear 330 traps set under the ice near lodges in Newfoundland indicated kits were as vulnerable at 1-3 m from the lodge as they were from 6- 9 m. There was no difference (P > 0.05) between the percentages of kits and adults or males and females trapped. Of 46 colonies, 15% were single, 24% were pair, and 61% were family colonies. Colony size averaged 3.5 beaver for 26 colonies totally removed, of which 13 were family colonies averaging 5.3 beaver. There was no difference (P > 0.05) in the sex ratio. Of the family colonies, 42% contained 2.5-year- old beaver, and 24% contained 3 beaver 2.5 years old or older. Of the pair colonies, 42% contained a yearling. J. WILDL. MANAGE. 46(3):655-661 Because beaver are colonial and re- stricted in their movements during winter freeze-up, and because trapping is the usual method of harvest, knowledge of trap response, colony size, and age and sex structure is of importance to manage- ment. Most available data indicate that there are slightly more male than female beaver born, but the sex ratio of adults favors females (Shelton 1966). Some wildlife agencies restrict trapping near the lodge because kits allegedly are more susceptible there than are adults. New- foundland regulations state that only 1 beaver per colony may be trapped. The extent to which trap response affects har- vest under these regulations is unknown. Colony size has been reported in North America and Russia, but usually without comment concerning harvest history or their distribution or status as random or nuisance. This study was undertaken to increase the understanding of the effect of several colony parameters on response to winter trapping.