Yellowstone's Northern Range - Greater Yellowstone Science ...

EXECUTIVE SUMMARY
The condition of the winter range of the northern Yellowstone elk herd
(refen-ed to here as the northern range) of Yellowstone National Park has
been of concern to the public, managers, and scientists for more than 70
years. Before 1970, almost all observers regarded the range as overgrazed due to an
overpopulation of elk. Other problems thought to have been caused by high elk
numbers included declines in woody vegetation, especially willow and aspen, declines
in white-tailed deer and beaver, and increased erosion. These concerns led to increasingly
aggressive attempts to control elk herd size, which peaked in the 1960s, when
thousands of elk were slaughtered. The agency's control actions resulted in a monumental
public outcry and U.S. Senate hearings that led to the termination of elk control in
the park.
Because of changing attitudes about natural systems in the scientific community
and growing uncertainty over how ecological processes worked in Yellowstone National
Park, National Park Service (NPS) managers and biologists decided to test the common
assumption that the elk were inevitably inclined to overpopulate the range and, alternatively,
to determine if the elk herd might be "naturally" regulated, or regulated by its
environment. Natural regulation of animal populations was an established topic in
ecology by the 1950s. In the 1960s and 1970s, by applying prevailing ecological theories
relating to natural regulation, NPS scientists provided substantial evidence that traditional
views of the range as overgrazed were either erroneous or based on incomplete information.
During the 1980s, concern over the condition of the range continued among the
public and the scientific community. In 1986, Congress funded a major study initiative
to address the overgrazing issue. Researchers noted that commercial range managers
defined an overgrazed range differently than did wildland ecologists. Use of commercial