Managing Wildlife, Habitat and People

During the birth of contemporary wildlife management in the 1930s, biologists such as Aldo Leopold began to understand that effective wildlife management was not just about understanding the relationship between animals and habitat, but between animals and people. Biologists began recognizing the concept of “carrying-capacity,” first coined by the cargo shipping industry, could improve wildlife management. Over time, application of carrying-capacity has let biologists better understand and manage wildlife-habitat relationships, or the “biological carrying-capacity.” Similarly, managing wildlife-human relationships has been improved by considering the “social carrying-capacity.”

Biological carrying-capacity (BCC) is the number of animals an environment can support indefinitely. When the environment has good habitat for a species, it will support more of those animals. In Illinois, we can expect a mix of agriculture, young forest and grasses to support high deer and turkey numbers. But what happens when deer and turkey become so numerous they eat all of their habitat? Their populations reach the BCC limit and population numbers naturally fall because they have less food and space to survive and reproduce. This natural population decrease then allows the habitat to recover, and population numbers follow. This is a natural process and occurs with nearly any organism given limited resources. Humans are an exception because we can manufacture the food, clean water and shelter needed to sustain immense population growth, to a point.

The problem biologists increasingly face, particularly with growing urbanization, is how to manage wildlife that become so numerous that they conflict with human interests. This is where the application of social carrying-capacity (SCC) comes into play.

SCC is the maximum number of animals capable of living in an area which is socially acceptable to people in that area. You might think about this as the number of geese you are willing to tolerate defecating on your sidewalk, how many raccoons you are willing to tolerate getting into your trash, or how many songbirds you would like to see at your bird feeder. Understanding SCC is important to understanding how to best manage wildlife in specific areas. For example, some municipalities in Illinois use hunting or trapping to reduce deer or raccoon populations, which have increased substantially due to the safe and food-rich habitat our neighborhoods provide.

When considering management goals for wildlife and habitat, biologists consider the BCC and SCC of each species. Although estimating BCC is straightforward, estimating SCC is tough because of the broad spectrum of public option on wildlife. That is why it’s so difficult for biologists to manage wildlife populations at a level everyone will be happy with. Fortunately, by combining the SCC with the BCC, biologists can work for a population management goal that is good balance for the animals, ecosystem and people.

So, if you are concerned how wildlife are managed, know that wildlife biologists are doing their best to balance what is best for the environment and society.

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Prior to joining the Illinois Department of Natural Resources’ Division of Wildlife Resources in December 2017 as the Wildlife and Hunting Heritage Program Manager Jared Duquette served as the Hunter and Trapper Recruitment Scientist with the Illinois Natural History Survey. Jared has a PhD in wildlife ecology and is an avid backcountry hiker, archery deer and waterfowl hunter, and harmonica player.