Reproductive Endocrinology and Musth Indicators in a Captive Asian Elephant (Elephas maximus).

Abstract

Even in the best situations, the artificial social constructs of captivity alter natural elephant behavior and unfortunately create distress. Asian elephants are powerful and intelligent animals that require consideration for their well-being and prudent management. The males present particular difficulties due to a temporary state of heightened aggressive behavior unique to male elephants called "musth." When he is in this state, the danger the elephant poses to other animals and the people around him is considerable. In addition to antagonistic behavior, musth is also characterized by temporal gland secretion and urine dribbling. In previous studies, musth has been attributed to elevated testosterone levels. This study attempted to enhance the knowledge base concerning these phenomena by examining hormone concentrations (n = 357) in Onyx, a male Asian elephant housed at Dickerson Park Zoo, with intermittent access to females (n = 1-5) over a 12-year period. Behavior and signs of musth also were recorded daily by elephant department staff. Musth indicators (temporal gland secretion, aggression, urine dribbling) increased with musth but not prior to it. We confirmed that temporal gland secretion was a better indicator of behavioral musth than urine dribbling. Hormones concentrations increased as musth approached, and presumably initiated musth indicators, but variability was high. Therefore, these hormones cannot be used to predict the onset of musth in this individual. Rather, the free/total testosterone ratio was a good indication of the 60-day pre-musth period. In addition, testosterone production and musth indicators increased in intensity when a young bull at the zoo started entering musth.