A 14-Year Study of Blarina brevicauda Populations in East-Central Illinois

Abstract

Short-tailed shrew, Blarina brevicauda , populations in east-central Illinois displayed annual population cycles within bluegrass ( Poa pratensis ), tallgrass, and alfalfa ( Medicago sativa ) habitats. There was no indication of multiannual population fluctuations in any habitat. Amplitudes of annual fluctuation were relatively consistent within each habitat type. Population density was significantly higher in bluegrass than in the other two habitats, and higher in alfalfa than in tallgrass from February to July. The annual peak in tallgrass occurred 3 months later (October) than in the other two habitats (July). Males were reproductively active January–July and females, March–September. Survival was highest in bluegrass, intermediate in tallgrass, and lowest in alfalfa. January–August precipitation >24% below the mean was followed by lower peaks in B. brevicauda populations in bluegrass and alfalfa; ≥9% above-normal precipitation was followed by higher populations in alfalfa and bluegrass. There was no correlation between precipitation and population density in tallgrass. There was no correlation between summer temperatures and numbers of B. brevicauda .