Snowshoe hares (Lepus americanus) use twigs and bark of woody plants as their source of food throughout the winter. The decision to browse a potential food source likely depends on the relative quality of the browse items and predator avoidance. In the southern part of their distribution, the forest includes a wider variety of hardwood browse and a potentially different set of predators than in the north. To determine hare browse choices and preference in the northern hardwood forest, we examined species specific in-situ browse intensity in 4X4 meter plots and along 50 m transects in northern Adirondack forests where snowshoe hare tracks had been observed in the past several years (2009- 2010). We also examined preference in feeding arrays for wild hares (cafeteria style). We asked: 1) what are the dominant woody species that hare browse in-situ, 2) what are the relationships among proportion of browsed twigs, browsed twig diameter, relative availability of browse species, and nutrient content, 3) how does in-situ browse choice compare with preference shown in feeding arrays that contain species less commonly found in high density browse areas. Finally, we asked 4) how does availability of the browse species vary with forest structure.
Results/Conclusions
For all woody deciduous species found in 4 or more plots where hare sign was abundant, the proportion of available tips browsed increased linearly with availability. Striped maple and red maple appear to be browsed in greater proportion relative to availability than American beech (these were most abundant). However, when feeding arrays were offered that contained more choice, hares showed significant preference for paper birch, yellow birch and sugar maple over the commonly available striped and red maple. These data and our correlative data on forest structure (percent and type of lateral and vertical cover) suggest that snowshoe hare trade-off gathering preferred browse in favor of browsing available food sources in the areas where they are safer from predators in winter. Preliminary chemical analyses of woody browse suggest that relative preference shown by wild hares for browse in arrays correlates weakly with nitrogen content and energy availability.
