Movements of Rodents Across Roads

In west-central Kansas, the capture-recapture method was used during summer and fall of 1976 to estimate movements of small rodents a crossroads. The seven species studied were the thirteen- lined ground squirrel (Spermophilus tridecemlineatus ), hispid pocket mouse (Perognathus hispidus), western harvest mouse (Reithrodontomys megalotis), deer mouse (Peromyscus maniculatus), hispid cotton rat (Sigmodon hispidus ), prairie vole (Microtus ochrogaster), and house mouse (Musmusculus). Grids were established on both sides of two gravel roads, a bituminous two-lane highway, and a divided interstate highway. Results indicated that rodents, with the exception of ground squirrels, did not cross roads: however, when artificially transported across roads, members of five species returned. Evidently, roads inhibit normal movements of rodents, but once displaced across roads, rodents will return home. Studies on the relationships of wildlife to roads have dealt primarily with game species (Kline 1965: Carbaugh 1975) and mortality caused by automobiles (Dickerson 1939: Davis 1940; Haugan 1944). Little attention has been given to the movements of rodents with respect to roads; only one published paper focuses on this particular subject (Oxley et al. 1974). These authors concluded that small forest mammals such as the eastern chipmunk (Tamias striatus) and the white footed mouse (Peromyscus leucopus) were reluctant to venture onto road surfaces where the distance between forest edges exceeded 20 m, and that a four- lane, divided highway might be as effective a barrier to the dispersal of small forest mammals as is a body of fresh water twice that wide. In research involving populations of cotton rats (Sigmodon hispidus), Joule and Cameron (1974) used paved roads 15 m wide to delimit study areas. They found \that the paved roads between plots effectively reduce small mammal movement to approximately 5 per cent of movement within plots, with some seasonal variation.\ The purposes of this study were to (1) determine if roads inhibit the movements of rodents and (2) ascertain if displaced rodents will return across roads.