Small-Mammal Distributions Across the Prairie-Forest Transition of Minnesota and North Dakota

Abstract

Thirteen taxa of small mammals were collected in the continuous forest, aspen groves, riparian woodland and prairie areas of the prairie-forest transition. Mammals captured were placed in three groups on the basis of habitat selection. Of the forest species, Peromyscus maniculatus gracilis was the most restricted and occurred only in or near conifer forest. P. leucopus noveboracensis was found in coniferous, deciduous and river-bottom forests and in large aspen groves. Clethrionomys gapperi had a similar distribution, but was also found in some small aspen groves with grassy ground cover. Tamias striatus was collected in the continuous forest and nearby large groves. Eutamias minimus and Synaptomys cooperi were collected only in the continuous forest. The prairie species, P. m. bairdii, Onychomys leucogaster and Microtus pennsylvanicus. were found essentially in grassland situations. P. m. bairdii also occurs in aspen groves and river-bottom forests where P. 1. noveboracensis is absent. M. pennsylvanicus appears to be a permanent resident in young groves with a grassy undercover. The non-selective species, Sorex cinereus. Blarina brevicauda and Zapus hudsonius, were found throughout the area in all habitats trapped. Sorex arcticus may also be present in moister habitats throughout the transition. The small-mammal fauna of the prairie-forest ecotone includes fragments of both prairie and forest faunas and reflects the state of flux in the plant associations.