THE IMPACT OF WOOD TYPE, SEASON, AND REPELLENT USE ON NORTH AMERICAN PORCUPINE DAMAGE

We evaluated the impact of wood type, season, and repellent use on North American Porcupine damage to forty installed posts along Rails-to-Trails property in Brockway, Pennsylvania, USA. Treatments were (1) pressure-treated Pine posts with Ro-Pel (a liquid repellent), (2) pressure-treated Pine posts without Ro-Pel, (3) Black Locust posts with Ro-Pel, and (4) Black Locust posts without Ro-Pel. We assessed new damage to posts 1 – 4 times per month from June 2007 – January 2009. All damage was to Pine posts (x− = 12.9 cm2, SE = 3.70 cm2) and no damage was observed to Black Locust posts. Observed damage to untreated posts (x− = 9.93 cm2, SE = 2.10 cm2) was 3.3 times greater than damage to posts treated with Ro-Pel (x− = 2.99 cm2, SE = 2.86 cm2). Total monthly damage to Pine posts was greatest in August (x− = 2.31 cm2, SE = 1.51 cm2) and there was no observed damage in February, October, and November. When examining damage by season, damage to Pine posts was 54 times greater in summer (June – August; x− = 1.62 cm2, SE = 0.567 cm2) than in fall (September – November; x− = 0.030 cm2, SE = 0.030 cm2). We suspect the seasonality observed may be related to salt loss and salt-seeking behavior. We suggest that landowners and managers who anticipate Porcupine damage consider using alternatives to pressure-treated Pine for their wooden structures. In addition, repellent applications could be timed to correspond with the peak of damage to reduce cost.