Evaluating passage use for small and medium sized mammals in an eastern Canadian boreal forest
While many studies have looked at how large mammals respond to road mitigation measures, few studies have examined the effects on smaller mammals or taken a multispecies approach. We investigated the effectiveness of three different types of wildlife passages along Highway 175 in northern Quebec for small and medium sized mammals using infrared cameras. Wildlife passages (n=17) were monitored year round from 2012 to 2014. Two research questions were addressed: (1) Do environmental and structural characteristics explain differences in crossing success across passage types?; and (2) Does the frequency of passageway usage differ by species? Using Generalized Linear Mixed Models, a global model and species-specific models for the most abundant species were generated to answer these questions.
Pipe culverts, one of three passage types, were significantly less likely to be crossed in general, and particularly by weasels. Passage success was less likely with a median present overall, except for weasels. Species’ responded to the passages differently, with crossing success decreasing as latitude increased and openness decreased. For micro-mammals, increasing latitude and the presence of artificial light decreased crossings. Taken together, these results have local and global management implications. By highlighting how agencies can engineer more effective wildlife passages, in particular by minimizing the barrier effect of the structures themselves, this study hopes to encourage further construction of wildlife passages on a larger scale.