The ecology of a free-living population of the ass (Equus africanus) at Kalpitiya, Sri Lanka Original Research Article

The ass was introduced into Sri Lanka many centuries ago, probably from north-eastern Africa by Arab traders, and became a conspicuous member of the herbivore fauna of the north-western coastal areas of the island. Now devalued as a ‘beast of burdenʹ by the internal combustion engine, it survives as a few small and isolated populations. A study of the population at Kalpitiya near Puttalam was started in 1995. Its members resemble the wild Nubian subspecies (Equus africanus africanus) closely in their external features. Monthly counts using the road-strip method indicate a density of 16.8 per km2 and a social structure of (a) small family units usually consisting of one male with one or more females and their young, (b) small groups of bachelor males and (c) isolated males. Feeding occupies the greater part of the daylight hours: mating and foaling occur throughout the year. About 85% of the population is adult and thus aged three years or more. Vertical sections of the cementum at the base of the upper M1 teeth from a sample of collected skulls suggest an annual increment of about 0.2 mm which includes two ‘darkʹ layers perhaps formed during the two dry seasons. On this interpretation the maximum longevity would be about 45 years. The subspecies forms an important part of the biological diversity of the coastal zone and appears to be excellently adapted to inhabit a marginal habitat without over-exploiting it. Its survival in Sri Lanka has been threatened particularly by loss of habitat due to indiscriminate development of prawn farms (which also destroy the coastal mangrove forests), and now by the resettlement of refugees from civil conflict in northern and eastern Sri Lanka, and potentially ill considered and over ambitious tourist developments. As at the least a rare breed of the species which is a feral relict, and possibly a genetically little modified form of the Nubian subspecies, which is close to extinction in its native land, it is in urgent need of management and protection based on conservation of its habitat.