But the fact remains that we have places to be and even a few well-intentioned road signs cannot slow us down. In our ceaseless efforts to connect our world, we don’t always consider the ways that our road network has fragmented the animal habitats it paves over.
The unpleasant task of shoveling the battered carrion from our roadways falls to local highway departments. But what exactly happens to the bodies from there? I reached out to representatives from a few local county highway departments and it turns out their methods vary, but most are taken to landfills or compost bins. Scavengers remove many of these animals before road crews have a chance to clear the roads, a valuable but underappreciated ecosystem service provided by crows, ravens, foxes, and the like.
A study published in the New Zealand Journal of Zoology found that seasonal peaks in road kill for specific species was dependent upon breeding periods and dispersal. Deer and moose are particularly vulnerable to vehicle collisions during their fall mating seasons, according to a representative for the New York State Department of Environmental Conservation (DEC). Disseminating information on these predictable changes in animal behavior provides some aid, but the number of incidents remains troubling. This suggests that accommodating for animal behavior could be more effective than attempting to educate human drivers.
A fact sheet published by the Defenders of Wildlife conservation group indicates that 1.5 million wildlife-vehicle collisions occur annually in the United States, with the majority resulting in animal fatalities. In New York, an estimated 30,000 deer are killed every year in vehicle collisions, according to DEC. There are also human consequences to account for, with wildlife collisions responsible for over 200 human deaths nationally and over a billion dollars in property damage, the Defenders of Wildlife reported.
The high rate of wildlife-vehicle collisions is partially the result of increasing land development. A study published in Wildlife Biology by John A Bisonette and Silvia Rosa states that 50% of land in the United States is within 382m (1253.28ft) of a road. This has resulted in a closer proximity between roads and animal habitats, with road density reaching 0.75km/km² (1.21mile/mile²) according to the same study. Phil Brown wrote an article for the Adirondack Almanack earlier this year about how increased land development has threatened remote areas in the Adirondack Park. According to a study, land that now qualifies as remote – at least three miles from a road and at least two miles from a lake allowing motorboats – has dropped to less than 3% in the Park.
Road salt poses another potential aggravator for wildlife collisions. Salty pools of water, which collect along roadsides, attract deer and moose, whose only other source of salt are aquatic plants. According to a study published by Paul Grossman and his colleagues in Ecology and Society, salt pools result in animal movement primarily during spring and early summer when aquatic plants are unavailable.
Mitigation strategies for wildlife-vehicle collisions have been employed in other states to some success. Road systems incorporating overpasses and coverts allow for animals to move across busy highways, and effectively reconnect fragmented habitats. The initial costs of these infrastructure projects could be offset by the resulting reduction in vehicle damages from wildlife collisions. According to John A Bisonette and Silvia Rosa’s study, deer collision mitigation strategies in Montana resulted in a 98.5% decline in deer mortality from a six-year period prior to construction. The Montana mitigation strategy combined fences with wildlife underpasses, whereas the study’s control lacked these features and resulted in only a 2.9% decline in deer mortality in the same period.
Hunter Peters recently completed an internship at the Adirondack Almanack.