Rodent populations on the northern Great Plains respond to weather variation at a landscape scale

Abstract

Extreme weather variation on the northern Great Plains of North America can potentially influence the abundance of grassland rodents across vast areas. We used the remains of 33,697 small mammals collected from owl pellets in central and western Canada over 15 years to determine the influence of weather on the annual abundance of deer mice (Peromyscus maniculatus), sagebrush voles (Lemmiscus curtatus), and meadow voles (Microtus pennsylvanicus). Weather variation affected the annual abundances of all 3 species; however, influence on deer mouse and sagebrush vole annual abundances was relatively small compared to that on meadow voles. This finding may indicate that factors other than weather (i.e., habitat availability) are more important for the abundance of deer mice and sagebrush voles at the landscape scale. In contrast, meadow voles were positively associated with the duration of snow cover above the hiemal threshold (20 cm), exhibiting up to 5-fold increases (i.e., irruptions) in abundance following winters of persistent, deep snow cover. Our study is the first to examine the effects of weather on landscape-scale abundance of rodent species on the northern Great Plains of North America, providing further insight into the role weather plays in driving rodent population fluctuations in this highly seasonal environment. © 2014 American Society of Mammalogists.