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Do animals feel safe using wildlife crossings?

Wildlife bridges and tunnels not only protect animals from vehicle collisions but also assist in preventing inbreeding among small and fragile populations that are hemmed in by roadways or other human development by helping connect them with a wider pool of potential mates. However, whether the animals themselves feel safe while using such wildlife crossings is not yet well understood.

Now, by reviewing a set of nearly 600 animal-activated videos, a research team led by the University of California, Los Angeles (UCLA) has investigated reactions of deer and elk around a wildlife tunnel beneath a four-lane highway in Alberta, Canada. The analysis revealed that the animals were less likely to use the undercrossing after they had displayed a vigilant or fearful response to passing vehicles. These findings suggest that wildlife managers should focus more on animals’ perceptions of their environments when designing wildlife crossing structures, in order to signal that a crossing area is safe.

“It’s only through studies like this that focus on how animals perceive and react to the stimuli in their environment — which can either attract them or repel them — that we’ll gain the necessary insights to develop effective wildlife crossings,” said study co-author Daniel Blumstein, a professor of Ecology and Evolutionary Biology at UCLA. “Importantly, different species are likely to respond differently, and other external contextual cues might also influence how a given species responds.” 

The video recordings showed that elk and deer on the roadside near the tunnel often shifted from foraging for food to becoming vigilant or even fleeing when vehicles passed on the highway above. Surprisingly, the animals appeared to react more strongly when vehicles passed infrequently than when the traffic flowed steadily.

“We are not certain why animals are more responsive to fewer vehicles,” said study senior author Erik Abelson, a research scientist at the University of Texas at Austin, who conducted this research during a postdoctoral fellowship at UCLA. “It is possible that when there are many cars barreling down the road, they can be heard from farther away and don’t surprise the animals as much.”

These findings show that animals respond dynamically to human activities in ways which can affect if and how they use wildlife crossings. While some animals, such as racoons, are so accustomed to human activities that they don’t respond negatively at all, others may be much more cautious. 

“If we can figure out ways to leverage wildlife behaviors, we may be able to make wildlife crossings more effective. For example, walls to dampen sound or to reduce the visual effects of passing headlights may encourage use of crossing structures. We hope that this study is just one of many that will examine different wildlife species and levels of traffic to better develop tools that increase the use of crossing structures by wildlife and, ultimately, protect the lives of humans and wildlife,” Abelson concluded.

The study is published in the journal PLoS ONE.

By Andrei Ionescu, Staff Writer

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