Thesis Title

Reproductive Endocrinology and Musth-Behavior of a Captive Male Asian Elephant (Elephas Maximus)


Connie Duer

Date of Graduation

Summer 2004


Master of Science in Biology



Committee Chair

Thomas Tomasi


Captive breeding programs for Asian elephants (Elephas maximus) in North America are dependent on successful management of male elephants. This is a difficult undertaking, which is made even more difficult by a temporary state of aggressive behavior unique to male elephants called "musth." Musth is not only characterized by aggressive behavior, but also temporal gland secretion (TGS), urine dribbling (UD), aphagia, and as a result of these, reduced immune system function. This study attempted to better understand these phenomena by looking at total testosterone (TT), free testosterone (FT), and estradiol (E) concentrations in serum from Onyx, a male elephant housed at Dickerson Park Zoo in Springfield, Missouri. Hormone concentrations were determined by radioimmunoassay (RIA). His musth-related behavior and physiological conditions were recorded daily by elephant staff on a musth report. We found that Onyx's hormone concentrations increased as musth approached, but variability was high. Musth behaviors increased during, but not prior to musth, and he tended to enter musth before females entered estrus. TGS, aggression, UD and the number of females in estrus increased with his hormone levels, however breeding behavior was not linked to levels of reproductive hormones. Although testosterone levels increased prior to musth, and presumably caused the musth behaviors, the high variability in hormone measurements does not make this a good way to predict the onset of musth.


Asian elephant, testosterone, musth, behavior, estradiol

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© Connie Duer