Green bridges in a re-colonizing landscape: Wolves (Canis lupus) in Brandenburg, Germany

Abstract

Gray wolves (Canis lupus) are recolonizing many parts of central Europe and are a key part of international conservation directives. However, roads may hinder the reestablishment of gray wolves throughout their historic range by reducing landscape connectivity and increasing mortality from wildlife-vehicle collisions. The impact of roads on wolves might be mitigated by the construction of green bridges (i.e., large vegetated overpasses, designed to accommodate the movement of wildlife over transportation corridors). In this study, we investigated the seasonal and diurnal use of a green bridge by wolves and three of their main prey species: red deer (Cervus elaphus), roe deer (Capreolus capreolus), and wild boar (Sus scrofa). We found that all four species used the green bridge. Wolves were most active in winter, whereas prey species were most active in spring and summer. All species were more active at dusk and during the night than at dawn and during the day. We found no evidence that wolf presence influenced bridge-use by prey species, consistent with other tests of the prey-trap hypothesis. Our results suggest that green bridges are used by wolves and prey species alike, and may foster connectivity and recolonization for these species in rewilding landscapes.