Overpasses intended for human use can be crossed by middle and large-size mammals

Abstract

Road overpasses cost more than underpasses and can be built for most terrestrial mammals to resolve and/or minimize effects from habitat fragmentation. Many overpasses intended for human activity might also allow wildlife passage. Using digital infrared cameras from 2015 to 2016 in Hokkaido, Japan, we evaluated such use in three overpasses, where two were designed for humans and one for wildlife. Nine mammal species were detected at the three overpasses. Three middle-sized mammals—raccoons (Procyon lotor), red foxes (Vulpes vulpes), and raccoon dogs (Nyctereutes procyonoides)—and a large mammal species, the sika deer (Cervus nippon), frequently used all of the overpasses. Our results showed that the overpass designed for wildlife was richer in species than the two overpasses for humans. However, results also showed that there were no significant differences in use among four animal species in the three overpasses. We propose the construction of small overpasses without plants to conserve habitat reconnection of middle-sized to large mammals. Arboreal species’ habitats need structural change with additional of plants.