Growth rates of the vole Microtus townsendii during a population cycle [male, female, spring, autumn, seasonal, growth rates, population density, vole, British Columbia, Canada]
1980
Beacham, T.D. (Bedford Inst. of Oceanography, Dartmouth, Nova Scotia (Canada). Marine Fish Div.)
Four populations of the vole Microtus townsendii were trapped concurrently with live-traps and pitfalls from May 1976 until June 1978. Males always grew faster than females. Voles born in the spring had the highest growth rate of any season, and growth rates decreased throughout the summer and autumn. Spring growth rates of male M. townsendii less than 40 g remained constant through the population cycle, but summer and autumn growth rates became progressively less. Growth rates of males over 40 g generally declined seasonally and through the population cycle, but summer and autumn growth rates became progressively less. Growth rates of males over 40 g generally declined seasonally and through the population cycle. Heavy-weight males present in peak populations gained weight throughout the preceeding winter while all other males lost weight; they also grew faster than medium-weight males at all weight ranges from the increase until the peak spring. After the peak spring, heavy-weight and medium-weight males grew at similar rates, which suggests that they had diffent asymptotic weights during this portion of the cycle.
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