Reducing Wildlife–Vehicle Collisions

Last weekend we were driving through Wynad sanctuary. Naturally we discussed the crossing of wild animals.  We had only recently read a good paper from US which appeared in Journal of Wildlife Management

Wildlife managers and transportation mangers are a worried lot when it to comes to roads passing through wildlife habitats. Mitigating the impacts of highways on wildlife and increasing driver safety is high on their agenda.

Wildlife underpasses are a good option but this has to be constructed very carefully. In this piece of research the researchers used camera and track surveys to evaluate wildlife use before and after construction of 3 wildlife underpasses and associated fencing on a new section of United States Highway 64 in Washington County, North Carolina, USA. Theyrecorded 242 occasions of white-tailed deer (Odocoileus virginianus) use of underpass areas before highway construction began.

After the construction of the underpass they collected 2,433 photographs of 9 species with deer representing 93% of all crossings. White-tailed deer use of underpass areas averaged 6.7 times greater after the new highway and underpasses were completed.

The researchers recorded 3,614 wildlife crossings of ≥20 species based on track counts. This represented most medium and large mammals known to occur in the area and several reptiles and birds. After completion of the highway wildlife mortality due to vehicle collisions were recorded during a 13-month period. There were 128 incidences representing ≥24 species. Within fenced highway segments, mortalities were lowest near underpasses and increased with distance from the underpasses.

More mortality was recorded in fenced areas when compared to unfenced areas. The researchers say with greater distance from an underpass, animals with smaller home ranges seemed less likely to reach the underpass and instead attempted to climb over or crawl under fencing.

The research clearly demonstrated that underpasses and fencing reduced the number of deer–vehicle collisions. The researchers sign off saying “Continuous fencing between underpasses may further reduce the number of vehicle collisions for deer but additional design features (e.g., buried fencing) should be considered for other wildlife species.”

Effectiveness of Wildlife Underpasses and Fencing to Reduce Wildlife–Vehicle Collisions

Matthew F. McCollister and Frank T. van Manen

Journal of Wildlife Management 74(8):1722-1731. 2010