Term of Award

Winter 1999

Degree Name

Master of Science

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Department

Department of Biology

Committee Chair

C. Ray Chandler

Committee Member 1

Stephen P. Vives

Committee Member 2

J. Michelle Cawthorn

Abstract

A main goal of zoological institutions is the conservation of rare and threatened species. Critical to this goal is an understanding of the behavioral ecology of these species so that researchers can develop strategies for their conservation, both ex situ and in situ. A prime example of the importance of behavioral ecology to captive management is the Jackson's hartebeest (Alcelaphus buselaphus jacksoni). Once widespread in Africa, hartebeest populations have drastically declined due to the effects of human overpopulation. Successful captive propagation of hartebeest in zoological institutions is a vital step in the conservation of this species. However, this goal is hampered by the presence of female dominance hierarchies within herds. The goal of this study was to elucidate the behavioral and physiological correlates of female dominance behavior. A better understanding of dominance in captive female herds of hartebeest may lead to increased reproductive success and optimize herd stability.

Among the three North American facilities working with hartebeest is the St. Catherines Island Wildlife Survival Center (WSC). The WSC has maintained breeding herds of the Jackson's hartebeest (A. b. jacksoni) since 1978. This study focused on a herd of ten female Jackson's hartebeest at the WSC. The goals of this project were 1) to quantify the structure of the dominance hierarchy within this herd of female hartebeest, 2) to examine the correlates of dominance rank by comparing behavioral data with stress- and reproductive-related hormone levels obtained through fecal steroid analysis, and 3) to set forth management strategies designed to optimize herd stability and reproductive success. This study took place over a seventeen-month period and was divided into 3 phases. Phase I occurred when there was no breeding activity in the herd. Phase II took place during the breeding season when a breeding male was present in the herd. Phase III occurred when the majority of the females were in their last trimester of pregnancy.

A linear dominance hierarchy was found to exist in this herd of hartebeest, with dominant females initiating the most aggression directed toward the subordinate females. Subordinate females spent a higher percentage of time alone or with other females of similar rank. Age was positively correlated with rank, while size and kinship were not factors. Overall aggression was at its highest during the peak of the breeding season and lowest just prior to calving.

Levels of progesterone indicated that the rate of highest aggression correlated with estrous cycling. Progesterone levels were not affected by rank. Synchrony in estrus cycling appeared during this study, with a period of anestrus occurring during the spring and summer months. Cortisol levels did not correlate with rank or with rate of aggression.

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