THE ROLE OF STRESS AND INDIVIDUAL RECOGNITION IN THE FUNCTION OF THE AFRICAN ELEPHANT’S TEMPORAL GLAND

Abstract

Biochemical measurements were made from a sample of temporal gland secretion from each of 5 wild African elephant bulls (23-38 yr of age) collected in Kruger National Park, South Africa. Total protein content was high (26-57 mg/ml), acid phosphatase ranged between 1.9 and 6.3 mM/h/mg protein and lactic dehydrogenase levels were undetectable. Total lipid content in the secretion averaged 80 mg% and ranged from 75-87 mg%. Triglycerides were just detectable, varying from 2-8 mg% and phospholipids ranged from 9-11 mg% (average 10 mg%). Cholesterol content was high, measuring 12, 19, 26, 36 and 70 mg% for 5 samples of secretion. Field observations indicated that stress triggered liberation of temporal gland secretion. Among 116 elephants collected in Uganda, secretory activity of their temporal glands was more frequent during dry (probably more stressful) than during wet seasons. Among 62 elephants driven by helicopter to roadways for collection in Kruger National Park, 23 driven relatively far and fast were in prominent musth; most of those driven slower and shorter distances showed no evidence of musth. The matriarchal leader of an elephant family near Lake Albert, Uganda developed very prominent temporal gland activity after 1 h and 45 min of vigorously defending 3 of her family members. Chemical individuality of cholesterol levels in temporal glands of 5 adult bulls suggested a pheromone-producing function which served for individual recognition by the African elephant. Direct observations of wild elephants suggested that the temporal gland functions as a scent gland helping to recognize other members of the group or to find them.