Aspects of the ecology of the Asian elephant Elephas maximus L. in the Ruhuna National Park, Sri Lanka

Abstract

Observations on the elephant Elephas maximus L. were carried out in the Ruhuna National Park, Sri Lanka, from May 1978 to June 1980. Solitary animals were the most commonly observed, of which 91% represented adult males. The most stable social organisation was that of the adult females and their attendant young. Adult males lead a solitary or semi-solitary life, joining the herds mainly for breeding. The population structure is composed mostly of adults and subadults. Within the herds, the adult sex ratio was in favour of the females. The average herd-size was 5·9. There was a movement of the elephants from the coastal areas towards the central and northern regions of the Park as the drought proceeded. The peak of activity of the groups appeared slightly later in the evening than that of the solitary animals. Sexual activity and breeding were observed in the dry season, while newborn calves were seen in the wet season. Data are not sufficient to establish a seasonal pattern, if any, in breeding. The minimum density was found to be 0·15 km −2. The average biomass was about 278 kg km −2. Since the beginning of the 19th century, the elephant population in Sri Lanka seems to have declined by 85%. Their future survival is certain to be limited to the National Parks, which should be large enough to include a variety of habitat types. Smaller Parks should be linked to larger ones, so as to minimise the risk of extinction through random events.