De Silva M., Dissanayake S., Santiapillai C. 1994.
Aspects of the population dynamics of the wild Asiatic water buffalo (Bubalus bubalis) in Rahuna National Park , Sri Lanka
J. South Asian nat. Hist. 1: 65-76.
A population of Bubalus bubalis L. was studied for two years in Rahuna National Park (RNP) in Sri Lanka by seasonal direct counting. The park contains a shallow river and a large number of water holes, most of which dry up during the dry season. The vegetation consist of scrub forest interspersed with grassland, which covers an area of about 30% of the park. The buffalo population in an area of 140 km 2 usually fluctuated between 500 and 600. However, after a prolonged drought period the population decreased to 300 in January 1993.
Although the observed male to female ratio up to the subadult stage is 1:1, that of the adults fluctuated between 1:4.7 and 1:1.9 favouring females, males being relatively more frequent during the breeding season. Since there appears to be no selective mortality of adult males, the observed deviation from 1:1 sex ratio could probably be due to adult males moving away from the study area into deeper forest.
The main breeding season of the buffalo in RNP lasts from March to May. Calves are born from end of December to about mid-May, from the end of the main rainy season to the beginning of the dry season when the grasses show a luxuriant growth; the peak of calving is in mid-January. Only about half the adult females appears to calve in any one year. The buffalo population in RNP is maintaining itself, any tendency of increasing being controlled by the enhanced mortality during prolonged drought periods, which occur once every few years.
The elephant (Elephas maximus), spotted deer (Axis axis) and sambar (Cervus unicolor) are the major competitors of the buffalo for the food resources in the park. The leopard Panthera pardus and the crocodiles Crocodylus porosus and C.palustris, and perhaps the jackal (Canis aureus) are the only significant predators of the buffalo and they too are important only during the calf and juvenile stages.