Co-use of existing crossing structures along roads by wildlife and humans: Wishful thinking?

This study assesses existing human-purpose underpasses below an unfenced high-traffic 4-lane highway in the Appalachian region of Quebec, Canada, as potential crossing structures for native mammal species. Eight three types (five water culverts with minimum height and width 1.8 m, one low-use gravel road byway, two railroad underpasses) were continuously monitored by motion-detection infrared camera traps time periods spanning up to 778 days (September 2016 November 2018). We asked how ratios successful crossings through (termed full crossings) aversions aversions) differed between species we explored influence human activity levels on use these wildlife. All had low observations (with averages less than 35 activities per day). Our results provide evidence that 21 mammals area successfully crossed at least eight observed a occasion. Some some regular basis, namely raccoon, red fox, white-tailed deer. propose classification into five co-use classes (no or very high co-use) explore relationship presence. found humans sharing passages four identified tolerant (high classes), but was be limited not occurring most other The strengths this include length during which monitoring took place, well placement cameras each structure (two facing inward outward) determine whether individuals displayed avoidance behaviour. suggest select show underpasses. patterns documented over two-year can assist future estimates permeability. Further, measurements have species-specific implications retrofitting constructing wildlife fences purpose-built passages.