Predators And Prey - And People

During the first part of the 20th century, when wildlife management was in its infancy, most people considered predators a threat to game populations.

Their reasoning seemed logical. Because predators kill game animals, killing predators should result in more game. Guided by this notion, and with enthusiastic support from sportsmen, state and federal wildlife agencies implemented rigorous predator control programs. To further encourage public participation in these programs, these agencies often offered bounties for predator carcasses.

It wasn't long before wildlife biologists started noticing flaws in the idea of predator eradication. Focusing on large-scale removal of small fur-bearing predators like raccoons and opossums had proven ineffective. Eliminating large predators, coupled with a ban on hunting to protect deer populations, had proven disastrous. With no predators to control population growth, deer overpopulate and ravage their habitat and, eventually, fall victim to starvation and disease.

Learning from these failures, wildlife managers began to understand that predators and prey exist co-dependently. More important, they also began to recognize that habitat quality and quantity are the primary keys to maintaining healthy game populations.

Unlike emphasizing predator control, providing good habitat for wildlife proved economical. The success of habitat programs prompted government agencies to eliminate bounty programs. Only recently have wildlife biologists managed game populations by emphasizing habitat. This new direction and policy even resulted in some predators, such as birds of prey, receiving protected legal status.

Wildlife professionals recognize, however, that predators can be a factor in the declines of specific prey populations.

In the late 1980s and early 1990s, for example, duck numbers across North America dipped to a 50-year low. Researchers discovered that in the northern prairie states and Canada, small predators, mostly raccoons and skunks, were destroying up to 50 percent of all duck nesting attempts by eating eggs and killing nesting hens.

Even so, wildlife biologists found that the increased predation had links to habitat quality.

"Broad swaths of vegetation that surround potholes in the northern United States serve as ideal breeding habitat for ducks," said David Wissehr, a waterfowl biologist with the Missouri Department of Conservation. "Extreme dry conditions in the late 1980s and early 1990s resulted in many potholes drying up.

"Ground surrounding existing potholes dried to a point that allowed farmers to cut hay and plant crops closer to the water's edge," he added. "These conditions forced ducks to nest in concentrated numbers in the remaining thin bands of habitat along the edges of potholes, leaving nesting