Feeding responses of snowshoe hares (Lepus americanus) to volatile constituents of red fox (Vulpes vulpes) urine.

This study investigated the influence of the volatile constituents of red fox (Vulpes vulpes) urine in suppressing feeding by snowshoe hares (Lepus americanus) on coniferous tree seedlings. Pen and field bioassays indicated that the odor of fox urine and its principal component, 3-methyl-3-butenyl methyl sulfide, had a negative effect on feeding behavior of hares. The other sulfur-containing compounds, 2-phenylethyl methyl sulfide and 3-methylbutyl methyl sulfide, as well as six other constituents, were not effective. Synthetic urine mixtures composed of eight and nine volatile constituents, respectively, did not suppress feeding in pen bioassays. However, the mixture of eight compounds in a field bioassay did result in significantly fewer seedlings being eaten by hares than in the control. 3-Methyl-3-butenyl methyl sulfide may act as an interspecific chemical signal which induces a fear or avoidance response in hares. Additional work is required to determine the optimum concentration and release system for 3-methyl-3-butenyl methyl sulfide to be used as a mammalian semiochemical in crop protection.