Modifying Scent-Marking Behavior to Reduce Woodchuck Damage to Fruit Trees.

Woodchucks (Marmota monax) damage fruit trees by gnawing on main stems during scent marking, a behavior unrelated to feeding. I tested whether damage could be reduced by providing alternative sites for scent marking or by applying predator odor to trees. Nearly all hardwood stakes supplied as alternative sites for scent marking were used, and the elapsed time from activation of a burrow until onset of damage to an adjacent tree was significantly greater for sites with stakes. However, the mean level of damage to trees was not significantly reduced. Impregnating hardwood stakes with sodium chloride increased their use as gnawing sites relative to untreated stakes, presumably due to dietary sodium deficits incurred by woodchucks during spring. Use of NaCl-treated stakes did not reduce damage to adjacent trees, however. Application of a predator odor, bobcat urine, as a topical spray reduced mean levels of gnawing by 98.3% relative to untreated trees, and placement of bobcat urine in capillary tubes at the bases of trees also resulted in significant reductions in damage over a 3-mo period. © 1991 by the Ecological Society of America.