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Student Investigates a Prickly Pest

2/3/2009 —

DuBois – Porcupines are well known for their sharp quills, which can cause significant damage to people and animals.  However, a Penn State DuBois student has found that the unapproachable creature can cause just as much damage to property by using its teeth. 

Wildlife Technologies Student Andie Graham is conducting an ongoing study into the damage porcupines cause to structures along a Rails to Trails recreational path in Jefferson County.  She began in April of 2007 by assessing a five-mile stretch of the Brockway Rails to Trail system, known to host an abundance of porcupines.  

“Several damage hotspots were found, and included items such as plastic culverts and signs, and wooden bridges and mile marker posts,” Graham said.  Obvious the damage was caused by an animal, she then had to pin point the culprit.  “It was determined to be caused by porcupine and not beaver due to visible teeth and claw marks, and the lack of wood chips surrounding the damage.  Beavers only eat live vegetation, which also helped in determining that it was caused by porcupines,” she explained.   

Two bridges, constructed of pine, showed the most damage.  Graham discovered a fence, made of naturally rot-resistance black locust, in the same area showed no damage.  To prove the porcupines had a taste for pine and not for locust, Graham placed 40 test posts in the ground in that same area.   Half were pine, and half were black locust.  Ten of each type of post were left untreated, while ten of each type were sprayed with a repellent spray intended to ward off porcupines. 

Over months of weekly inspections Graham found she had proven her hypothesis. The black locust posts went untouched, while the pine had been chewed.  However, Graham is still searching for a way to preserve pine structures as well, and may be onto something.  

“The wood had been stripped from the pine posts and was found on the ground next to it,” Graham said. “Based on this information, the repellent seems to deter porcupines from consuming the posts, but not from damaging the posts.”  

Graham also has a theory as to why the porcupines are attracted to the pine structures in the first place.  “It’s important to note that all of the pine posts have been pressure treated with preservatives, some of which contain sodium,” she explained.  “Since porcupines are fond of salt, this could explain why they prefer the pressure treated pine over the untreated locust.” 

Graham’s work from this point on will involve experimentation with different types of repellents and investigating seasonal patterns of the animals.

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