Wildlife overpasses are used to mitigate road-driven forest fragmentation and restore ecological connectivity, yet their effects should be evaluated in the habitat context of forest-associated species. We applied a control–impact (CI) design to evaluate the fragmentation-mitigating effects of wildlife overpasses for mammals by comparing habitat use between crossing-connected forest patches and nearby unconnected patches within the same road corridor, while analyzing environmental correlates. Based on home-range requirements, we defined habitat-limited small patches (<3 km 2 ) and habitat-suitable large patches (≥3 km 2 ) and interpreted crossing effects under this patch-size context. From July 2023 to October 2024, we deployed one to two camera traps per patch (24 stations across 22 forest patches), classified species as forest-associated species or habitat generalists, and fitted species-specific generalized linear models (GLM) to evaluate effects of crossing presence, patch-size context, and environmental variables on habitat use. Across all patches, roe deer used connected patches more. In small patches, habitat use was higher in connected patches for roe deer and yellow-throated marten, whereas Asian badger showed no significant crossing effect and tended toward higher use in unconnected patches. Habitat generalists generally showed higher habitat use in unconnected patches, with significant effects for water deer and wild boar. Forest-associated species showed species-specific responses to forest variables, whereas habitat generalists showed generally negative associations with forest and distance-to-land-cover variables; slope and traffic responses varied among species. Overall, the effects of wildlife overpasses were most evident for forest-associated species, supporting patch-scale, context-based evaluations that incorporate habitat specialization and surrounding habitat conditions.
Jeong et al. (Tue,) studied this question.