PLASMA TESTOSTERONE LEVELS IN RELATION TO MUSTH AND SEXUAL ACTIVITY IN THE MALE ASIATIC ELEPHANT, <i>ELEPHAS MAXIMUS</i>

Abstract

Summary. Testosterone was measured in the peripheral blood plasma of eleven male Asiatic elephants, using a competitive protein-binding assay. When the animals showed no signs of musth, the testosterone levels were low (&amp;lt;0·2 to 1·4 ng/ml) ; as they began to come into musth and the temporal glands started to enlarge, the testosterone levels rose (4·3 to 13·7 ng/ml), and when the animals were in full musth, with discharging temporal glands and an aggressive temperament, the levels were extremely high (29·6 to 65·4 ng/ml). Musth may therefore be comparable to the rutting behaviour of some seasonally breeding mammals, although, in the elephant, there is some indication that it may be induced by sexual activity.