Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa; Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa; Reproductive Biology Unit, German Primate Centre, Kellnerweg 4, 37077 Göttingen, Germany; Applied Behavioural Ecology and Ecosystem Research Unit, School of Environmental Sciences, University of South Africa, Private Bag X5, Florida 1710, South Africa; Save the Elephants, Transboundary Elephant Research Programme, P.O. Box 960, Hoedspruit 1380, South Africa; Department of Biomedical Sciences-Biochemistry, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria
Ganswindt, A., Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa, Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa, Reproductive Biology Unit, German Primate Centre, Kellnerweg 4, 37077 Göttingen, Germany; Muenscher, S., Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa; Henley, M., Applied Behavioural Ecology and Ecosystem Research Unit, School of Environmental Sciences, University of South Africa, Private Bag X5, Florida 1710, South Africa, Save the Elephants, Transboundary Elephant Research Programme, P.O. Box 960, Hoedspruit 1380, South Africa; Henley, S., Applied Behavioural Ecology and Ecosystem Research Unit, School of Environmental Sciences, University of South Africa, Private Bag X5, Florida 1710, South Africa, Save the Elephants, Transboundary Elephant Research Programme, P.O. Box 960, Hoedspruit 1380, South Africa; Heistermann, M., Reproductive Biology Unit, German Primate Centre, Kellnerweg 4, 37077 Göttingen, Germany; Palme, R., Department of Biomedical Sciences-Biochemistry, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria; Thompson, P., Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa; Bertschinger, H., Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa
Sexual activity in mature male African elephants is predominantly associated with the occurrence of musth, a state or condition which refers to a set of physical, physiological and behavioral characteristics, including an elevation in androgen levels. Although musth appears to be energetically costly, the degree to which it is associated with changes in adrenal endocrine function (e.g., glucocorticoid output) is still unclear. To investigate the possible effect of musth on adrenocortical function, and the impact of socioecological changes on androgen and glucocorticoid levels, six adult African elephant bulls were followed for 13. months in the Kruger National Park, South Africa, and observations and fecal sample collection for endocrine monitoring was carried out about twice weekly. Our data showed that the occurrence of musth was associated with reduced glucocorticoid output, suggesting that musth does not represent a physiological stress mediated by the hypothalamic-pituitary-adrenal axis. This confirms previous findings in captive-housed animals, providing evidence for a suppressive effect of the musth condition on adrenocortical activity. Furthermore, a seasonal effect on androgen and glucocorticoid levels was found, which appears to vary depending on the reproductive status of the animal. The results also indicate a relationship between the presence or absence of social partners and changes in testicular and adrenal endocrine activity. Finally, the data confirm previous findings in captive-housed elephants, that an elevation in androgen concentrations usually occurs before the onset of physical musth signs, and therefore support the idea that the change in androgen levels represents the initial stimulus for the musth condition. © 2010 Elsevier Inc.