Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Wildland Resources

Department name when degree awarded

Wildlife Management

Committee Chair(s)

Jessop B. Low


Jessop B. Low


An "exclosure" is defined by Daubenmore (1940) as an experimental area which is protected from the activities of a particular class of animals by a barrier such as a fence or screen thereby controlling a single factor of environment, namely, the animal influence.

Several different types of exclosures are employed by the land management agencies in Utah. Small portable "paddocks" a few feet square are extensively used to gauge seasonal grazing pressure by livestock. Permanently fenced areas, ranging up to many acres in size, serve to demonstrate the effects of livestock use on the range. Another modification is the "big game" exclosure.

Typically, big game exclosures in Utah are fixed installations consisting of 3 parts. The first is fenced to exclude both big game and livestock and is referred to as the "total-protected area." The second part is fenced to exclude only livestock and is referred to as the "game-only" area. The third part is unfenced (often designed by (stakes) and subject to use by all classes of range animals. It is referred to as the "open-range" area. Where there is no livestock the game-only area is omitted, thus making an exclosure having only 2 parts.

Big game exclosures came into use in Utah when deer populations conflicted with livestock interests in central and southern Utah during the early 1930's. As a result of the increases in deer numbers 2 groups were opposing certain policies of the land management agencies. On one hand, stockmen, threatened with grazing allotment cuts, believed that overabundant deer, and not livestock, were mainly responsible for the deteriorating grasses and forbs. On the other hand, sportsmen could not believe overpopulations possible and refused to harvest the deer. A tool was needed to demonstrate to these diametrically opposed interests the actual circumstances, and big game exclosures fitted that need.

Big game exclosures were first built in Utah by R. L. Turpin of the Utah State Department of Fish and Game and Orange Olsen and H. M. Christensen of the U. S. Forest Service. Three small exclosures were erected in 1932 on Beaver Mountain of the Fishlake National Forest, the first in Baker's Canyon on deer winter range, the second near Merchant Valley on deer intermediate range, and a third south of Big Flat on summer range. Additional exclosures were added in 1933 on the summer range of Beaver Mountain.

These pioneer exclosures demonstrated that deer had little effect on herbage, preferring browse instead, and that livestock were responsible for overgrazing the forbs and grasses.

Different land management agencies subsequently established other big game exclosures on important ranges of the State, located for the most part where local problems and interests dictated. No policy was followed in their positioning, design, and study, and many have been neglected.

The objectives of this study were fourfold:

  1. To describe the existing big game exclosures in Utah.
  2. To point out some of the effects of big game and livestock on the range.
  3. To investigate differences in deer use between game-only areas and the surrounding open-range.
  4. To evaluate the role of big game exclosures in range management in Utah, and indicate the direction of future endeavor.

The present study was sponsored by the Utah State Department of Fish and Game, in cooperation with the Utah Cooperative Wildlife Research Unit at the Utah State Agricultural College, the U. S. Forest Service, and the U. S. Bureau of Land Management. During the spring and summer of 1954, each exclosure was visited and systematically studied, land managers were interviewed, and past records reviewed. No previous study of this scope has been made in the western states1/, although the use of big game exclosures is widespread.

Early records indicate that deer, and other big game animals, were not abundant when the first settlers came to Utah in 1847. Unrestricted year around hunting further reduced their numbers until a low was reached in the years following the turn of the century, 1900. However, the "buck law", predator, animal control, game refuges, law enforcement, and a probable ecological plant succession from grasses to browse on ranges overgrazed by livestock, brought a rapid increase in deer numbers (Durrant, 1952). By 1930, deer "problem areas" were first noticed, and by 1940 important segments of the game ranges were being destructively browsed. Deer have been more abundant in recent years than at any time since white man first visited the area (Rasmussen and Gaufin, 1949).

In 1890, the range lands of Utah supported unregulated use by approximately 360,000 beef cattle and 2,000,000 sheep (Rasmussen and Gaufin, 1949). Heaviest livestock pressure on the ranges was probably felt. from 1915 to 1920 as a consequence of the demands for meat created by World War I. Following that war, livestock reductions were effected, but concurrent with these reductions deer numbers were growing, so that total animal pressure was probably not much relieved (Anon., 1950). Today (1954), Utah's cattle numbers are likely increasing, while sheep numbers are decreasing. Shorter seasons on the range and increased use of feedlots, however, have lessened over-all cattle pressure on the range.

From historic records and the examination of isolated tracts that escaped overgrazing, Utah's foothill ranges are thought to have once been well supplied with native forbs and grasses (Julander, 1954). With the arrival of settlers, and as their cattle and sheep herds prospered, much of this cover was destroyed. In its place grew big sage, juniper, and other shrubby species that were better able to withstand use by livestock. Simultaneously, as large areas in the foothills and mountains of the State grew to browse, the deer herds began to respond to protection from hunters and predators. The combination of abundant feed and protection produced a favorable condition for deer that lasted until about 1942, when their numbers outgrew the capacity of important parts of the range (Julander, 1954).