A Microhistological Investigation of Winter Diets of White-Tailed Deer in Relict Eastern Hemlock Stands, Upper Peninsula of Michigan

Abstract

To better understand winter foraging patterns of Odocoileus virginianus (White-tailed Deer) in the context of global change, we assessed foraging trends using microhistological analysis of fecal pellets from 2006–2018 across a network of monitoring plots in 39 relict Tsuga canadensis (Eastern Hemlock) stands in the western Upper Peninsula of Michigan. We found that deciduous browse comprised the majority of the diet, but conifer species were also eaten. During severe winters, Eastern Hemlock and Abies balsamea (Balsam Fir) were more prevalent in the diet, whereas in mild winters, Thuja occidentalis (Northern White Cedar) was more prevalent. Because Northern White Cedar comprises only a small amount of the forest community in these stands, deer were likely traveling beyond these winter yarding areas to forage. The relationship between conifer consumption and winter severity highlights the importance of energy conservation for winter survival of White-tailed Deer. More extreme winter weather is predicted with climate change, potentially prolonging confinement and limited forage availability, which is liable to alter energy budgets of deer, thus potentially altering population dynamics.