While wildlife passages are built to maintain habitat connectivity and evaluated on how effectively they achieve this, an often overlooked aspect of road mitigation is how the passages may be used for reasons other than their intended purpose, particularly when a vegetated median may provide additional habitat. We investigated why small and medium sized mammals in northern Quebec were less likely to cross the entire width of Highway 175 when passages were segmented by a vegetated median and examined what factors may influence passage use and foraging in the median. Wildlife passages (n = 6) were monitored continuously from May 2012 to August 2015 using infrared cameras. Using generalized linear models, we compared complete crossings with and without foraging and exploratory crossings with and without foraging to see if mammals were changing their use of the passages based on various temporal and structural characteristics associated with the passages.
Results/Conclusions
Higher ambient temperatures inside the passages led to increased foraging events during complete highway crossings. Passages at higher elevations were foraged in more than passages at lower elevations before a crossing occurred, but foraged in less during explorations. Passages with wider medians were foraged in more during an exploration and crossing than passages with narrow medians. Newer passages experienced more foraging during a crossing and exploration than did older passages. Season affected foraging in the median during crossings, with lower levels of foraging in the summer compared to winter, while foraging was higher in the winter than summer. For explorations, foraging was lower in spring than both summer and autumn. Further, micromammals were less likely to forage during exploratory crossings compared to all other mammal species studied. Our results demonstrate that highway passages that preserve some of the natural habitat in their design, such as by maintaining access to a vegetated median, can limit complete functional loss of the highway corridor for wildlife.