JACKSON, Wyo. — Conservation author Ben Goldfarb’s research into road ecology reveals the ways that road signage is ineffective for wildlife, making wildlife crossings necessary to combat both roadkill and the “barrier effect.”
Last month, Goldfarb visited Jackson Hole to discuss his new book aimed at raising awareness of how roads shape nature and the ways that humans manage that impact.
“I think that’s one of the irony of roads, because of all the mobility and freedom they bring us, they do the opposite for essentially all other species.”
Ben Goldfarb
“Roads are so ubiquitous, they’re somewhat invisible to us,” Goldfarb said at his author talk at Spring Creek Ranch. “When we do think about them, we think about them in relatively positive terms. They’re symbols of human mobility and connection and freedom. I think that’s one of the ironies of roads, because of all the mobility and freedom they bring us, they do the opposite for essentially all other species.”
Goldfarb identifies two main ways that roads hinder wildlife populations, the first of which is roadkill. While Goldfarb suggests roadkill has become such a common phenomenon it’s largely invisible to people, he calls it an “enormous biological catastrophe.”
A 2023 peer-reviewed research paper confirms roadkill is the most common cause of death in almost a third of all wildlife populations studied, which puts road mortality from wildlife-vehicle collisions ahead of disease, hunting and predation by other animals as causes of death. According to Goldfarb, roadkill “hijacks evolution itself” when the defense mechanisms that evolved over thousands of generations are useless in the face of a car or truck speeding down a highway.
But Goldfarb considers the barrier effect a potentially even bigger problem. The barrier effect is a result of steady streams of traffic preventing wildlife from crossing roads and accessing critical resources, where the road acts as a barrier to animals reaching certain habitats.
Goldfarb points to a study of the Red Desert mule deer herd that migrates from Rock Springs to Hoback Junction where satellite collars on the deer show I-80 acts as a barrier that causes up to 40 percent of animal deaths due to inability to access habitat. Another satellite collar study shows how a grizzly bear in northern Montana spent two years trying to cross I-90 before finally making it across in 2021.
“Any road with more than 10,000 cars today should be considered absolute barriers to all wildlife,” Goldfarb said in his talk.
But solutions to these problems have historically defaulted to road signage alerting drivers to the presence of animals, which Goldfarb’s research suggests accomplishes little, if anything. Even though signage has evolved in the past decades, Goldfarb still refers to it as “visual pollution” and “litter on sticks.”
The best tool that Goldfarb says should be prioritized to combat road impact is wildlife crossings. He points to how grizzly bears in Banff were suffering genetic fragmentation due to roads, but decades of research on constructed wildlife crossings confirms that these structures are effective at restoring the population and promoting an intergenerational network of crossings.
Goldfarb acknowledges that crossings are much more expensive than road signage, but he says communities will actually save money by investing in building these structures because it will prevent even costlier collisions. The Nature Conservancy says the most recent adjusted estimated total costs for injuries and damages are $8,264 per deer collision, $21,723 per elk collision and $38,615 per moose collision, excluding the values of each animal involved in a crash.
However, despite the benefits to them, Goldfarb warns that many road ecologists are wary of how the construction of wildlife crossings can become justification for ill-conceived road expansion projects.
