Wildlife Deer Populations

Why Manage Deer?

Deer are an important part of Lake County's natural areas. Like other native species, they are beautiful and have a place in the ecosystem. But in some of our highest-quality Preserves, their numbers are so high that habitats are becoming unbalanced. These large plant eaters are consuming a great number of plants. Left unchecked, this could lead to the loss of native plants and animals, including endangered species.

One of our key roles is to preserve a diversity of habitats for future generations. To maintain a balance between deer and other species, our policy is to reduce deer numbers in the most humane and effective way possible.

How did this happen?

Deer habitat improved greatly as this region gradually became settled. The landscape now offered enough food and cover for deer to thrive. Coupled with the loss of predators, deer numbers surged.

Our winters are not severe enough to reduce herds. Unfortunately, automobiles are the only significant "predator" of deer in Lake County. Some people compound the problem by feeding deer, which may encourage the population to climb even more.

Most female deer start to have young when they're just two years old. And for about a dozen years, they can easily have twins each year.

How do you know their impact?

Our wildlife biologists have put up "deer exclosures" at several Preserves. Deer can't get into these fenced-off areas but squirrels, woodchucks and other plant eaters can. In nearby control areas, deer are allowed. We can measure and compare the plants in both areas to assess the deer's impact on the habitat.

Data collected since 1988 show that deer do pose a threat to the number and variety of plants. Also, those favored by deer are less vigorous and produce fewer flowers outside the exclosures. To see an exclosure, visit Ryerson Conservation Area. Plan your visit for spring, when differences are most apparent.

Humane removal

Deer are removed from several Preserves under humane conditions by qualified sharpshooters. Work occurs when Preserves are closed, and all venison is donated to Lake County charities. This is the best option now available and is used by agencies nationwide.

Deer numbers are estimated each winter with helicopter survey flights. Our goal is 15 deer per square mile, based on published research recommendations. At that level, we have a better chance of sustaining habitat for other species.

It's hoped that contraceptives will one day offer an effective form of population control, so we're staying abreast of research in that field.

They're all connected

Deer management is just one part of our Natural Resource Management Program. We use several other safe and field-proven techniques to help restore balance in your Forest Preserves.

Deer removal is not pleasant, but you can't give preference to one native species at the expense of all others. If trillium, trout lily and other plants disappear from our Preserves, the animals relying on them could also disappear.

Most affected sites are in the Illinois Nature Preserves System, a collection of the state's highest quality natural areas. Preserving this natural legacy is worth the effort. And evidence shows this nationally recognized program is working.