The park's higher elevations provide summer range for an estimated 38,000 grazing wildlife called ungulates - elk, bison, pronghorn, deer, bighorn sheep, and moose. But each year the accumulating snow spurs most of them to lower areas where the winter is warmer and drier, where there is more open range and fewer forests. A third of this range is on public and private lands north of the park, where wild ungulates often compete with livestock for grassland in winter. At that time, the number of elk wintering on the Northern Range was down to about 4,500. Instead, the elk population fluctuates over time as its birth and death rates are affected by a combination of factors, including winter severity, the quantity and quality of available forage, emigration, parasites, disease, and predation by other animals.
Elk are also subject to hunting when they leave the park.
The Effect of Natural Regulation on the Northern Range In a world where progress is generally assoc-iated with our ability to control and shape our physical environment to some ideal vision of the way we think things should be, the idea of accepting natural regulation has been controversial. It's obviously not appropriate for all animals in all parks, or in any situation where it is necessary to protect human life or property. But three decades of experience have shown that, combined with regulated hunting in the surrounding national forests, natural regulation has controlled the size of the elk population. Although the number of elk wintering on the Northern Range has increased in response to the conversion of more than 10,000 acres north of the park from livestock to wildlife use and increased migration to that land, it has also responded to weather variations and other environmental factors. Elk increased during years with mild winters and wet summers, and declined after the drought and fires of 1988.