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Deer survival is influenced by many factors including disease, predation, weather, and hunter harvest. In the Upper Peninsula (UP), deer survival is especially influenced by winter food supply and cover. Deer commonly rely on felled tree tops and subsequent growth of tree saplings for winter food. Additionally, deer seek out landscapes with a high proportion of conifer trees, such as cedar and hemlock, to obtain shelter from snow and wind. The availability of these habitats effects over-winter survival in the UP.
Predators also play a role in the survival of deer, particularly fawn survival during the spring and summer. Although some predators (such as coyotes) are able to take deer of any age, other predators (such as black bears) are able to catch fawns only during the first couple weeks of life. During the winter, when deer are hampered by snow and in poor physical condition, predators are able to prey upon deer easier. Understanding deer survival, and the factors that influence it throughout the year, is vitally important for proper management of the deer herd.
White-tailed deer provide food, sport, income, and viewing opportunities to UP residents and visitors. In some areas, deer overabundance results in damage to farm crops, deer-vehicle accidents, and suppression of forest vegetation. For these reasons, it is important to monitor the deer population and understand the reasons why it increases or declines.
Historically, deer abundance in the UP has been affected by the intensity of timber harvesting and winter severity. Although these factors still exert a strong influence on deer populations, the role of predation is getting more attention by both sportspersons and deer managers. Research is needed to better understand the impact of predation on deer, while also determining how predation is influenced by winter weather and deer habitat conditions.
Figure 1. Percent annual population change of black bear, gray wolf, coyote and white-tailed deer in Michigan’s western Upper Peninsula from 1990-2006).