Date of Award:

1968

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Advisor/Chair:

Jessop B. Low

Abstract

Dinosaur National Monument, in northwestern Colorado and northeastern Utah, is comprised of 206,409 acres and contains several deer winter ranges. A need for deer studies developed because of winter deer mortality and deteriorating range conditions'on some parts of the Monument. Approximately 500 deer winter on the Yampa Bench and approximately 300 deer winter on the Island Park winter range. These are the two main winter ranges within the Monument. Deer on the Yampa Bench migrated an average of 7.3 air miles to the south and summered on the Blue Mountain Plateau during the summer of 1966. This Plateau is owned by the Bureau of Land Management and private individuals. Deer from the Island Park winter range migrated an average of 22.6 air miles to the northwest in 1967, onto the Diamond Mountain Plateau and the Ashley National Forest. Deer tagged on the Split Mountain winter range were found to travel to the south and west. These deer summered mainly upon private lands. Deer remain on Harpers Corner approximately 10 months of the year until deep snows force them to lower elevations on Yampa Bench in early February and from which they return in early April. Vegetation composition and density data gave evidence that the deer and sheep which use the west end of the Yampa Bench are competing for forage. Carrying capacity data suggest that sheep use of this area be reduced. Carrying capacity data for the Split Mountain range suggest that cattle use should be reduced. If grazing use was kept off this area until June, the grasses would have a better opportunity to put on good growth before utilization of them began. Other winter ranges within the Monument are well within their carrying capacity limits. Thus, a safeguard exists on most winter ranges against deer winter mortality. The physical condition of deer on the Monument's winter ranges was very good during the winters of 1966 and 1967. Consequently, deer winter mortality was found to be slight on the Monument's ranges during these two winters. A few does remain on winter range areas within the Monument to summer. They generally 'use the river islands and the relatively inaccessible canyon slopes as fawning grounds. Nearly all of the deer that winter within the Monument migrate to higher elevations off the Monument to summer. This makes them subject to reduction by hunting. Deer hunting pressure on the hunting units adjoining the Monument has in recent years been sufficient to keep deer numbers within their respective winter range carrying capacities.

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