Feeding avoidance of balsam poplar by snowshoe hares is related to abundance of buds

In boreal forests of North America balsam poplar (Populus balsamifera) stems contain several chemicals distasteful to snowshoe hares. Some chemicals occur in internodes, others in buds. We examined whether an antifeedant chemical in buds (2,4,6-trihydroxydihydrochalcone) also inhibited hares from feeding on internodes. This chemical was painted onto buds of palatable willow (Salix lucida) twigs which were presented to harts in cafeteria trials. Hares avoided twigs with painted buds and the degree of aversion was related to the abundance of painted buds. Although the number of buds per unit mass of balsam poplar stems declined from one to five years old, the remaining buds were sufficient to induce a feeding deterrence.