Beaver population ecology in interior Alaska

Abstract

The ecology of beaver (Castor canadensis Kuhl) populations along two streams in interior Alaska was studied in 1972 and 1973. The two study areas were similar in most respects, except for the history of human trapping intensity. The heavily trapped population exhibited the following contrasts to the essentially unexploited population: (1) higher mortality among adult age classes, (2) higher survivorship of the prereproductives, (3) a sex ratio with a preponderance of females, (4) decreased age at first breeding and consequently, (5) a smaller average size at maturity. Males appear to expend lower effort for parental activities than do females, and consequently exhibit higher survivorship than their mates. Population regulating mechanisms, management implications, and the evolution of an optimal life history strategy are discussed. The distribution and abundance of beaver colonies were related to habitat types and characteristics of the physical environment by multiple linear regression analysis.