Importance of balsam fir as winter forage for white-tailed deer at the northeastern limit of their distribution range

Abstract

Interspersion of dense coniferous stands that offer cover and more open mixedwood stands providing food resources has been recommended for the management of white-tailed deer (Odocoileus virginianus) wintering yards in northeastern North America. On Anticosti Island, at the northeastern limit of this deer's distribution range, previous studies have shown continuous decline of deciduous browse. As native balsam fir (Abies balsamea) stands progressively shift to white spruce (Picea glauca), the persistence of the deer population will increasingly depends on its capacity to use white spruce stands. To provide insights into deer responses to long-term changes in their habitat, we investigated resource use along a gradient of expected habitat quality for deer. Stand use increased with the proportion of balsam fir, reaching an asymptote when > 40% of the stand's basal area was composed of fir. Stand use does not appear to be related to snow interception since sinking depth was lower in white spruce forests. Deer using white spruce stands mainly consumed balsam fir (72%), whereas spruce represented only 17% of their diet. The consumption of arboreal lichens increased from 6% in January to 21% in March. The observed patterns of habitat use and the composition of the winter diet confirm the dependence of deer on balsam fir in winter and give additional support to the hypothesis that litterfall from balsam fir provides an alternate food source sustaining high deer density in a boreal forest without predators.Nomenclature: Anonymous, 2005.