Masters Theses

Date of Award

12-1984

Degree Type

Thesis

Degree Name

Master of Science

Major

Ecology and Evolutionary Biology

Major Professor

Michael R. Pelton

Committee Members

James Carter, Edward Clebsch, Ralph Dimmick

Abstract

A total of 1310 locations was obtained on 18 radio collared black bears (Ursus americanus) in Pisgah National Forrest, North Carolina, during 1982 and 1983. Male home ranges averaged 3205 ha in summer and 6931 ha in fall. Female home ranges averaged 872 hectares in summer and 1712 hectares in fall. Nine of the collared animals were killed by hunters during the study, 4 of these illegally.

Bear habitat use was analyzed in relation to timber management parameters available in the U. S. Forrest Service "Continuous Inventory of Stand Condition" and other parameters derived from stand and topographic maps. Chi-square analysis indicated that bears preferred yellow poplar-oak and brush cover types at the expense of softwood cover types; oak-hickory stands where used in approximate proportion to their availability. In summer bears preferred stands less than 10 years old and stands between 50 and 70 years old; during the fall the preference for young stands disappeared but the preference for stands 50 to 70 years old continued. Minor differences related to sex and year were noted, but in general these patterns were related to food habits; summer soft mast is available in recent clear cuts; fall hard mast is relatively abundant in the 50 to 70 year old stands as acorn production in most oaks peaks at this age. Preference for yellow poplar-oak stands over oak-hickory stands may be due to annual differences in mast production between types, and the greater availability of other foods in the yellow poplar-oak stands.

Other habitat variables considered in the analysis of habitat use included stand condition, operability , method of cut, management type, topography, habitat diversity, and road density. Significant preferences or avoidances of categories within these variables were less easily explained, in part because some data useful in timber management have little relevance to bear habitat use.

Multiple regression models considering all the above mentioned variables with bear use of individual stands as the dependent variable were constructed. These models explained approximately 15% of the variance in habitat use. Inclusion of understory community data, which were available for only a small part of the study area, increased the variance explained to approximately 30%.

A regression analysis relating the number of times individual bears crossed roads to the density of roads in the home range indicated that logging road densities may begin to restrict bear movements at densities of 1.25 km/km2.

Conclusions from the study were that hunting is the primary human activity affecting bears in the area. The current program of regenerating 10% of the area every decade may ensure a stable food supply by making 50 to 70 year old mast producing stands available consistently through time. However, the benefits of regeneration through clearcutting must be weighed against the increased vulnerability of bears to hunting which will result from roads constructed in association with clearcutting.

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