Predators helping prey

Despite serving as their top predator in Michigan, wolves can positively impact deer populations statewide.

A wolf standing alone in the wild.
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When we think of the interaction of wolves and deer in Michigan, for many people, their first inclination is to assume that wolves are bad for the deer population. Wolves are, after all, the top predator in Michigan and white-tailed deer are their primary food source in the Great Lakes states, according to the International Wolf Center. So, how could an animal that kills another actually be beneficial to the species being killed?

There are several important concepts to understand when it comes to wolf-deer dynamics, and most predator-prey relationships of any kind. First, many prey species have developed traits that enhance their ability to avoid being killed by predators. White-tailed deer, for example, are very fast and agile, have excellent hearing, can discern many different smells from quite a distance and utilize their white tails to alert each other of any impending threat. Many prey species also have an impressive ability to defend themselves against their foe.

Based on the findings from New Mexico State University Extension, this means that wolves are usually most successful in their hunts when targeting less vigorous prey, such as old, injured or diseased animals, which leads to a second important concept to understand: some wolf predation each year is compensatory, meaning that wolves are killing deer that would have died anyway. In other words, the mortality caused by wolves may be substituting for some other form or cause of mortality—starvation, disease, old age, weather (e.g., severe winters) and others. 

In any given area, there is only enough food, water, shelter and space available to support a certain number of individual prey species—its carrying capacity. If the population is higher than the carrying capacity, then degradation of the habitat can occur (e.g., over-browsing of plants and other food sources) and a number of individuals may die from factors such as limited food availability and spread of disease. So, the presence of predators can actually allow for the creation of better habitat for all wildlife species by giving tree and plant species a chance to regenerate.

Finally, there has been research recently conducted by the National Academy of Sciences in Wisconsin suggesting that the presence of wolves reduces the incidence of deer being hit by cars on roadways. Since wolves utilize open areas, such as roadways, to aid in finding prey, deer learn to avoid these areas. The researchers found that this behavioral change may reduce car-deer collisions by up to 24 percent in Wisconsin counties with wolves.   

Although it’s sometimes hard to accept the notion of your favorite animals being killed by predators, it is a part of the natural cycle. Whether you’re a deer hunter, wildlife watcher or just simply like to see deer, Michigan State University Extension believes supporting healthy wildlife populations is something we must all consider.

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