Demographic Responses of a Chipmunk (Eutamias townsendii) Population with Supplemental Food

Abstract

If chipmunk (E. townsendii Bachman) populations are limited by food when independent of other factors, then provision of a preferred supplemental food should increase density and related demographic attributes. Chipmunk populations were live-trapped from the autumn of 1976 to the spring of 1980 in 2 coastal forest-cutover ecotones at Maple Ridge, British Columbia [Canada]. Extra food was supplied during 1977 and 1978. The fed population increased 40-50% above the control population and maintained this difference through the 2 yr of the experiment. Juvenile survival, during the summer and through the winter hibernation period, was increased in the fed population over that of the control. Body weights were higher and juveniles grew significantly faster in the population with extra food than in the control. Range length tended to be less for chipmunks in the fed population. After the food was withdrawn, the population density declined on the experimental area and related demographic variables became similar to those in the control. Food limits population size in Townsend''s chipmunk.