Recipe for Reducing Roadkill

A lion that was struck by a car earlier this week in Washington had to be shot (4 times) to end its life while it was reportedly screaming and thrashing in the ditch on the side of the road. Endangered Florida panthers living amidst a network of roads in the last vestige of wildlands in Florida are facing dangers like getting flattened by semis. A small, isolated population of lions in the Santa Monica Mountains gets closer to extinction every time one gets hit on the freeway. And families enjoying one of the seven wonders of the world have their vacation come to a screeching halt when their car collides with a mountain lion at Grand Canyon National Park (see photo).

Photo caption: P8, a subadult male, suffered fatal injuries while crossing East Rim Drive, July 2005

Roadkill is nasty for drivers and animals alike. And it takes a toll on wildlife. All told, millions of animals are killed by vehicles each year across the world. For large mammals like mountain lions that tend to occur in low densities and take several years to raise their young, the loss of an individual can have a snowball effect on the population dynamics. For example, if you were to hit, say, the last known female mountain lion in the Santa Monica Mountains while she was raising her litter of four cubs, that could have spelled the end of that population. That's what we in the field call a local extinction. For larger, more connected populations that aren't currently on the brink of extinction, combining road kill with the usual sources of mortality (like disease, poaching, hunting, eating rat poison, rampant habitat loss, fighting over territory, and wandering into towns) could put them on that trajectory.

Even if you don't give a rat's ass about maintaining connected populations of wildlife, you should be worried about roadkill. Deer, elk, and moose could be considered the most dangerous animals in the United States. They hop out in front of cars like so many obstacles in an obstacle course in great numbers every single night and get hit by cars, causing all kinds of damage to vehicles, injuring drivers and passengers, slowing down traffic, and generally making life miserable for the people who collided with them.

There are more and more roads, and more and more cars on those roads everyday. And in my opinion, not enough is being done to decrease the ever skyrocketing amount of roadkill that comes along with all those cars on all those roads.

But there is a solution! Wildlife crossings. In fact biologists have been studying wildlife crossings for quite some time now, determining what type of crossing appeals to which creature, how big, small, light, or dark it should be, even using data from GPS collars to determine where the crossings should be. Deer and Elk tend to like wide open, vegetated structures, while lions, foxes, and turtles can make do with dimly lit culverts. Yippee, you say, why don't we have these wonderful crossings everywhere?

Exactly. Canada has some great examples we can follow, especially near Banff National Park where they have reduced the traffic-related mortality of all large mammals on the Trans Canadian Highway by more than 80 percent.

So what are we waiting for? We're not. Construction of wildlife crossings is underway in some parts of the country including the Oro Valley near Tucson, AZ. Nevada is building its first wildlife overpass, and groups like the I-90 Wildlife Bridges coalition, Green Highways, statewide Missing Linkages projects in California and Arizona (full disclosure: my pet projects), and countless others have been on top of this issue for a while, pushing for a more wildlife-friendly transportation infrastructure. I hope that the trend toward building safer highways for us all takes off.