Colorado State University Study Finds Lack of Fire a Factor in Decline of Mule Deer Habitat

Most people think putting out a natural forest fire is beneficial to wildlife, but for the mule deer herds across the West that are projected to be below population objectives, that might not be true.

Two researchers at Colorado State University’s Natural Resources Ecology Laboratory have found fire suppression is a factor in the decline of quality habitat and food supply for mule deer on the Western Slope of Colorado.

The study was funded by the Colorado Division of Wildlife and conducted by Daniel Manier, a postdoctoral research associate, and senior research scientist Tom Hobbs. Manier and Hobbs discovered that lack of fire is part of a complex combination of ecologic changes that might be contributing to the declining growth of mule deer populations.

Mule deer prefer plants that are close to the ground. They eat grasses and wildflowers in addition to many shrubs. When trees and dense shrubs become overgrown, they compete with plants that deer prefer to eat, eventually changing the composition of plants in important deer habitat. In the past, natural fires have cleared deer habitat of trees and shrubs, which are replaced with new vegetation, thus creating a beneficial and plentiful food source.

"Deer have evolved over thousands of years with natural disturbances of the landscape, and when fire is removed, habitat conditions change in ways that are detrimental to deer," Hobbs said.

Manier and Hobbs also found that fire suppression, which led to a gradual increase in forested areas in the region, caused an acceleration in canopy coverage in the area that was studied. The increase in tree cover caused a reduction in grazing areas.

"The lack of fire caused an initial encroachment on the habitat, but there have been conservation efforts to increase the quality of the deer environment," Manier said. "The question is have those efforts been enough to begin to increase the population?"

Along with fire suppression and the related increased forest coverage, human activity in the region also has contributed to the reduction in quality mule deer habitat.

"We’re not seeing a single stress that’s causing the slowing of growth among the deer population, but there has been a definite change in the quantity and quality of habitat for this particular species," Hobbs said.

For more information about the study, call Manier at (970) 491-7715 or Hobbs at (970) 491-5738.