Science News: Road ecologist examines

highway tolls on animal populations

by Kate Moore '12
NEWS EDITOR

One of the deadliest decisions a porcupine can make is crossing a busy road in Upstate New York. According to Erika L. Barthelmess, associate professor of Biology at St. Lawrence University, porcupines take the “most frequently hit” title among road kill in the area. In fact, medium—sized animals such as raccoons, skunks and porcupines are far more likely to meet their demise on a highway than the more obvious victims, such as deer.

Barthelmess shared her research on road ecology in a recent lecture entitled “Roads and Wildlife: The impact of roads on mammal population in Northern New York.” However, she was quick to point out that the title of her talk was misleading.
“One of the real challenges of road ecology is, if I tell you that 100 porcupines are killed, how do we know if that’s an important number?” said Barthelmess. “Interpreting these numbers is very challenging if you don’t have an abundance of data on the particular organisms you’re studying.”

Though Barthelmess has made use of distance sampling and mark-recapture methods, she has not yet been able to conclude if the high frequency of porcupine deaths poses a considerable threat to the population. Given that porcupines are long-lived animals and only produce a single offspring per year, she believes it may be likely that roads represent a serious danger to porcupines and other rodents and small mammals.

Barthelmess gathered data on road impacts by routinely checking three routes in the Canton, NY area for road kill. After surveying 7,904 kilometers over the course of 44 weeks, Barthelmess found that omnivorous and herbivorous animals constituted a larger portion of victims than carnivores, and that medium-sized animals were most likely to be hit. She also discovered that peaks in porcupine road-related deaths coincided with mating and dispersal periods.

Though unable to conclude if the high rate of porcupine deaths represents a threat to the species, Barthelmess pointed to potential solutions such as highway over- and underpasses that allow animals to cross roads safely. However, these passageways also present a problem by channeling all animals, regardless of species, into one area. Though a porcupine’s chances of surviving a road-crossing would be better if it took a tunnel, it would still be in danger if a natural predator used the tunnel at the same time.