Population Density, Life Span, and Mortality Rates of Small Mammals in the Blue-Grass Meadow and Blue-Grass Field Associations of Southern Michigan

Publisher Website
Google Scholar
Abstract
Small mammals were live-trapped and marked on study areas of blue-grass meadow and blue-grass field association at regular intervals to determine population densities, life spans, and mortality rates over a 5-yr. period, from 1938 through 1942. The meadow vole (Microtus pennsylvanicus pennsylvanicus). lemming vole (Synaptomys c. cooperi) and jumping mouse (Zapus h. hudsonius) showed marked annual fluctuations in abundance. The prairie deer-mouse (Peromyscus maniculatus bairdii) and wood mouse (P. leucopus noveboracensis) varied in population density from yr. to yr. but showed no evidence of marked cyclic or irruptive variations in numbers. Closely related spp. failed to show parallel trends in population density unless there was also similarity in ecological habits. Spp. with generally similar habits showed some concurrent trends in population density regardless of phylo-genetic relationship. The avg. life span in nature of the prairie deer-mouse was estimated at 4.88 [plus or minus] 0.2 months, that of the wood mouse at 4.64 [plus or minus] 0.21 months, and that of the meadow vole at 4.23 [plus or minus] 0.22 months. In all of these spp. the life span in nature is much shorter than the potential life span as detd. from captive animals. The short life span observed in nature is mostly attributable to predation.