Term of Award

Winter 2002

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 Vives

Committee Member 2

Bruce Schulte

Committee Member 3

John Averett

Abstract

With increasing species extinctions and dwindling natural habitats, conservation has become a fundamental necessity for the maintenance of biodiversity. Since many in situ habitats can no longer guarantee successful natural populations, ex situ measures (e.g., captive breeding) have been employed. In recent years there has been a remarkable increase in the use of captive propagation procedures for maintaining populations of endangered and threatened taxa. Although captive breeding has played an important role in the recovery of some species, adequate success has remained elusive for many taxa. The African hartebeest (Alcelaphus buselaphus) is a good example of the challenges faced in a captive setting. Once widespread in Africa, hartebeest populations have declined due to agricultural expansion, cattle grazing, and an increase in poaching practices, forcing the extinction of one subspecies and currently threatening the survival of others. Unfortunately, captive populations ofhartebeest face challenges as well, including social aggression, reproductive difficulties, and spatial constraints. Understanding the behavioral ecology of the hartebeest is therefore essential for the development of successful techniques for captive management. The goal of this research was to quantify the consequences of social dominance in a female hartebeest herd and to quantify baseline testosterone levels in male Cape hartebeest (Alcelaphus buselaphus caama) and Jackson's hartebeest (Alcelaphus buselaphus jacksoni).

Currently, there are only three captive management centers in North America that house hartebeest and are familiar with the challenges of this species. The St. Catherines Island Wildlife Survival Center (WSC) presently houses both Cape and Jackson's hartebeest. My study focused on a herd ofeleven female Jackson's hartebeest and four males, and a herd offour female Cape hartebeest and three males. Specifically, I will address 4 questions: 1) Do lower-ranking females suffer more aggression or less access to resources; 2) Does the presence ofa breeding male alter dominance interactions among females; 3) Do baseline testosterone levels suggest a suitable time period for gradually introducing males into a bachelor herd, and 4) Do elevated testosterone levels indicate times of greater copulatory behavior in breeding males? Additionally, a final objective ofthis thesis was to develop an ethogram ofagonistic behaviors in Cape hartebeest females. This research took place over a fifteen-month period and was divided into three phases for the Jackson's female herd and two phases for the Cape female herd based on the presence of the breeding male. Phase I for both herds occurred before the breeding male was introduced. Phase II for both herds occurred while breeding activity was ongoing with the introduction of the male. Phase III, only in the Jackson's herd, occurred once the male was removed.

A stable and linear hierarchy was found in the female Jackson's herd, with higher ranking individuals initiating more agonistic interactions. However, subordinate females did not necessarily receive the most agonistic threat. Low-risk agonistic encounters were most abundant over the course of the study, and overall agonistic interactions between females decreased with the introduction of the breeding male. Analysis of repeated close proximity with other females of similar rank suggested that individuals were most often nearest to those females closest to them in rank. Rank did not influence time spent away from the herd or use of shade, but the two lowest-ranking females were alone most often and used less shade than any other female, suggesting that they may need special management attention. Additionally, a feeding hierarchy did exist within the female herd, with higher-ranking females eating earlier than other individuals.

Levels of fecal testosterone were not affected by breeding opportunity nor subspecies difference, but did suggest seasonal variation. This seasonal influence implies a possible 'window of opportunity' for gradual introductions of male hartebeest into a bachelor herd during the winter months (November through February) when testosterone levels are at a minimum.

Copyright

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