University of Illinois Extension

IDNR’s Deer Management Strategy

How Many Deer?

Deer are often seen in herds during late winter. Photo courtesy of the Illinois Department of Natural Resources.

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There is no simple answer to the question of: "How many deer make up a healthy deer population?" Deer density per square mile (640 acres) indicates the number of deer in an area, but without knowledge of the quality of the habitat in the area, the number conveys little information about the deer population. The importance of, and concern about, the number of deer per square mile differs depending on whether the deer are located in the suburbs, in a natural area with a mix of forest and grasslands, or in an area under agricultural production. Most people have difficulty visualizing the number of deer per square mile or per county, or whether the deer numbers would be problematic.

The number of deer that a landscape can support while still remaining "healthy" over the long-term is called the ecological carrying capacity. The ecological carrying capacity can be lower or higher than people might expect because of the problems and damage that the deer can cause to Illinois’ different habitats. As a result, the Illinois Department of Natural Resources (IDNR) manages Illinois’ deer population based on the number of deer in a given area that society will tolerate or allow (cultural carrying capacity), but also considers ecological carrying capacity, especially of the state’s natural areas.

By definition, anyone who has some interest in Illinois deer belongs to one or more "special interest groups". These include hunters, wildlife observers, farmers, homeowners, outfitters, nursery owners, conservationists, motorists, crop insurance providers, businessmen, and many others. Each of these "special interest groups" has a very different perspective on the size and condition of the deer population in Illinois. The IDNR takes the diverse, and often opposing, public input and works to develop a deer population level that is acceptable to the majority of people in a given area.

Evaluation and Damage Topics