LB 16-144 - Effectiveness of Wildlife bridges on the Size of Mammal’s home-range

Effectiveness of wildlife bridges in preventing habitat fragmentation caused by road development must be evaluated quantitatively for wildlife conservation. Methods for assessing wildlife bridge effectiveness need to vary according to the size of the home-range of mammals because small mammals use wildlife bridges as habitats whereas medium and large mammals use them as corridors. In this study, for small mammals, we identified the routes of striped field mouse (Apodemus agrarius) using the capture-recapture method with live traps and implemented the general linear model to derive the environmental variables affecting the usage of the wildlife bridge by this species. For medium and large mammals, occupancy model with camera trapping was used to compare the occupancy rates in the wildlife bridge and surrounding forests. Consequently, fifteen mice were recaptured, none of which crossed the wildlife bridge, and seven mice moved between the surrounding forests and the wildlife bridge. Vegetation cover (1–2, 2–8, and 8 m over), vegetation composition, and maximum diameter at breast height (DBH) were the environmental variables that were positively correlated with the use of wildlife bridges by striped field mouse, while the slope was negatively correlated. Wild boars (Sus scrofa), water deer (Hydropotes inermis), and raccoon dogs (Nyctereutes procyonoides) were the most observed medium and large mammalian species. Wild boars, which had the largest home-range, had similar occupancy rates in the wildlife bridge and the surrounding forest, while those of water deer and raccoon dogs were a little different. In conclusion, striped field mouse use the wildlife bridge as a habitat and not a corridor; increased density of shrubs and trees and low slopes in the wildlife bridge and the surrounding forest increases the mouse density, thereby creating a sustainable ecosystem near the bridge. The similar occupancy rates of medium and large mammals indicate the significant effectiveness of bridges as corridors. From our result, for mammals, wildlife bridges can be utilized as both of habitats and corridors; thereby wildlife bridges can contribute to conserve wildlife.