Habitat selection by small mammals of riparian communities: evaluating the effects of habitat alteration

Small mammals of riparian communities in Iowa were studied during the summer using liveand snap-trapping techniques. Six general habitat types were identified from the herbaceous vegetation on 28 study plots selected to represent a range of habitats from open fields to deciduous forest. Predominant habitat alterations were grazing, timber removal, and stream-channel realignment. Small-mammal species diversity was highest in channelized habitats and lowest in dry floodplains. An index of breadth of habitat usage was calculated for 9 species of mammals; white-footed mice (Peromyscus leucopus) exhibited the most generalized habitat usage. With the use of stepwise multiple regression, relationships were determined between small-mammal species abundances and 12 variables describing microhabitat features. In many instances, small-mammal numbers also were correlated significantly with each other. The potential effects of 6 habitat alterations on the 9 small-mammal species are predicted. J. WILDL. MANAGE. 44(1):16-24 Suitable habitat probably is the most important factor influencing the distribution and abundance of small mammals within their geographic ranges (Baker 1968:101, Vaughan 1972:250-256). Some small-mammal species have specific habitat requirements and consequently are limited in their distribution, whereas others occupy a wide variety of habitats (Kaufman and Fleharty 1974, Kirkland and Griffin 1974, Briese and Smith 1975, Miller and Getz 1976). Reports of the general habitats occupied by small mammals are common in the literature, but few studies have quantified the factors within a locality that influence a species abundance. Recently, small-mammal abundance and distribution have been related to several measures of habitat structure (M'Closkey 1975, M'Closkey and Fieldwick 1975, M'Closkey and Lajoie 1975, Dueser and Shugart 1978, Holbrook 1978). Habitat disturbances such as streamchannel realignment (Possardt and Dodge 1978), clear-cutting (Kirkland 1977, Martell and Radvanyi 1977), fire (Krefting and Ahlgren 1974, Fala 1975), and strip mining (Verts 1959, DeCapita and Bookhout 1975) can affect small-mammal populations and alter community composition. Regardless of the nature of disturbance, if vegetation is changed and habitat is altered, populations of some species may benefit while others are affected adversely. The objectives of our study were (a) to determine habitat preferences of some small mammals and the factors influencing their abundance; and (b) to quantify the effects of habitat alterations, particularly stream-channel realignment and grazing, on community composition and species abundance. Although this study was conducted in southwestern Iowa, the results are applicable to other riparian communities, especially those with similar small-mammal communities. We thank the people of Guthrie County for allowing us to sample small mammals on their property. A. Brackney and D. Schlapkohl assisted in the field, and 1 Journal Paper J-9463 of the Iowa Agriculture and Home Economics Experiment Station, Ames. Project 2085, funded by the U.S. Fish and Wildlife Service, Office of Biological Services, National Stream Alteration Team. 2 Present Address: 9025 W. Herbert, Milwaukee, WI 53225. 16 J. Wildl. Manage. 44(1):1980 This content downloaded from 157.55.39.243 on Thu, 06 Oct 2016 04:44:14 UTC All use subject to http://about.jstor.org/terms HABITAT SELECTION BY SMALL MAMMALS * Geier and Best 17 D. F. Cox and M. Hand provided help with statistical analyses. Vegetation data were collected by J. P. Vogler. R. B. Dahlgren, W. L. Franklin, and R. Q. Landers reviewed an earlier draft of the