Demography of southern red-backed voles (Clethrionomys gapperi) and deer mice (Peromyscus maniculatus) after logging in north-central Ontario

Populations of Clethrionomys gapperi and Peromyscus maniculatus were investigated on newly harvested upland black spruce (Picea mariana) clear-cuttings and in control areas (uncut, selective cut, older clear-cuttings) near Manitouwadge, Ontario. On control areas Clethrionomys had increased breeding intensity, better summer survival rates, and a relatively greater number of young in 1978 relative to 1976 and 1977. Those conditions appeared to be unrelated to summer weather and occurred after a cold, wet spring with a delayed snowmelt. Numbers of Clethrionomys on new clear-cuttings declined to nil over the first two summers following timber harvest. Demography on new clear-cuttings was similar to that on control areas except for poorer juvenile survival rates and fewer young. The disappearance of Clethrionomys from recent clear-cuttings was likely due to direct mortality. Demography of Peromyscus on control areas was similar each year except in 1978 when there was an increase in the breeding intensity of males and a decrease in the proportion of young. Numbers of Peromyscus on new clear-cuttings increased over the 3 years. Demography was similar on clear-cuttings and control areas in 1978, but in 1976 and 1977 the clear-cutting population had an excess of males, greater reproductive intensity of both males and females, more wounding of males, and less wounding of females. A highly mobile, young, male-dominated population with a high reproductive rate and a good summer survival rate was present on the 1- and 2-year-old cuts. Recent clear-cuttings in upland black spruce act as dispersal sinks for Peromyscus and provide new habitat for colonization by presaturation dispersers.