There are three big take-aways from my master’s research project that was published recently as a open-source article.
- Wildlife crossing structures do, in fact, promote crossings for large mammals in general.
- But, the location really matters.
- And, we need WAY more structures if we hope to completely restore connectivity of movement.
Andis AZ, Huijser MP and Broberg L. 2017. Performance of arch-style road crossing structures from relative movement rates of large mammals. Front. Ecol. Evol. 5:122. doi: 10.3389/fevo.2017.00122
In general large mammals are 146% more likely to cross through the structures than any random point they mosey by in the surrounding habitat. This indicates that there is a funneling effect for the structures. This is great news, and it corroborates some of the wildlife-vehicle collision reductions we’ve seen on this highway. But, if our goal is to promote entirely free movement across the highway corridor, this means that we would need to install enough structures to have about half the road (40.7%) length undercut by wildlife tunnels. It is worth considering that our study used the habitat within 300m adjacent of the structure alongside the road as our control plots, so this is really only true for animals that are already habituated enough to even approach the road. If we had placed our control plots out in the wilderness, I think the data would have told a much different story, since we know that many animals are reluctant to even approach road corridors.
Now that this research is finally published and off my todo list (where it’s been for almost 2 years), I appreciate a minute to reflect on the process. This was my first real foray into academic science. My undergrad in wilderness philosophy had me analyzing metaphoric reconstructions, and in my professional conservation career I facilitated and utilized academic research, but never created it. There are a MILLION things I would have done differently if I could go and do this study over.
However, considering this was a major project to complete, off-the-couch, within a single field season of a masters program, I’m really pleased. I had a steadfast crew of interns to accompany me in the field every couple of weeks when we switched camera sites. I got to work with a great collaborators and mentors in Marcel Huijser and Len Broberg. I got to hang out on the beautiful Flathead Reservation all summer under the shadow of the Mission Mountains. And I gained a glimpse into the Salish and Kootenai Tribes’ respect for the land and their fight for an ecological highway (… a fight that lasted almost 20 years; Kroll’s 2015 article1 is a great overview).
Press:
The Wildlife Society – Along busy Highway 93, large mammals choose crossing structures
ScienceDaily – No more deer in the headlights: Study finds large mammals do use crossing structures
The Missoulian – Wildlife road crossings work well for deer, less so for bears
Macazine – Kein Hirsch mehr im Scheinwerferlicht: Studie zeigt, dass große Säugetiere Straßenkreuzungen verwenden (German news)
1Kroll, G. 2015. An environmental history of roadkill: Road ecology and the making of the permeable highway. Environmental History. 20:1. 4-28. https://doi.org/10.1093/envhis/emu129