Doctoral Dissertations

Date of Award

5-1991

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Ecology and Evolutionary Biology

Major Professor

Michael R. Pelton

Committee Members

Edward Clebsch, David S. Etnier, Sandy Echternacht, Ralph W. Dimmick, Boyd L. Dearden

Abstract

Data on age, sex, body measurements, survival, and reproductive condition were collected from 1702 black bears (Ursus americanus) trapped in the Smoky Mountains (SM), 1972-1989. The age structure suggested a lightly to moderately exploited bear population. Bears of Great Smoky Mountain National Park (GSMNP or Park) were significantly (P = 0.026) older (mean = 4.52 yr) than those of Pisgah (3.86 yr) National Forest (P < 0.076). SM females had a mean minimum reproductive age of 4.2 yr, birth interval of 2.4 yr, and litter size of 2.0 cubs. The percentage of lactating females was significantly associated with age (X2 = 20.6, 2 df, P < 0.001), and lactation rates were significantly related to white oak mast production (r2 = 0.51, P < 0.01). The annual mortality rate was 26% and was lowest for Park bears (22%) and highest for those of the national forests (30%). Density ranged from 0.09 to 0.35 bears/km2, and the intrinsic rate of growth (2-11%) indicated a slightly to moderately increasing population.

Both extrinsic and intrinsic factors govern the population. Food is the chief control of bear reproduction. Hunting mortality appears to regulate the bears population in the national forests, and male aggression and subsequent subadult dispersal govern bear abundance of the less-exploited Park population. Given these factors, and the cumulative effects of inconsistent hard mast production, poaching, and a habitat threatened by the gypsy moth (Lymantria dispar), roads, and resort development, this bear population may be jeopardized.

Gender was associated with the bear's status (i.e., panhandler/wild) (panhandler: 60% male, wild: 54% male, P = 0.056). Wild male bears were significantly older than panhandler males (3.9 vs 2.9 yr, P = 0.0001); wild female bears were older than panhandler females (4.9 vs 3.7 yr, P = 0.004). Male and female panhandlers were significantly heavier than their wild counterparts (P < 0.05), and panhandler bears grew faster than wild bears. The number of lactating females was significantly associated with status (P < 0.001); 56% of the panhandler and only 33% of the wild females were lactating.

Panhandlers were more fertile and larger than wild bears likely reflecting the panhandlers' better access to and use of high-energy, human-made foods particularly during years of natural food shortage. Small amounts of these foods, the availability of which varies with panhandler bear management, appear to make differences in body size. Dispersal and the large home-range size of the males and subadults probably explain the propensity of these bears to become panhandlers. The above findings as well as differences in demographic characteristics among wild bears within the Smoky Mountains are further discussed as they relate to the nutritional qualities of the environment.

Neck and chest circumferences and total length were significant (P < 0.0001) predictors of body weight. The predictive capabilities of these variables were reliable, especially at the low0to-mid range of bear weights. This predictive relationship should ease the collection of weight data on black bears in the Smoky Mountains.

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