Behavioural Ecology of a Grassland Antelope, the Blackbuck Antilope cervicapra: Linking Habitat, Ecology and Behaviour

Abstract

The blackbuck (Antelope cervicapra), a medium-sized antelope endemic to the Indian subcontinent, is found in diverse shortgrass and savanna habitats. It displays extreme sexual dimorphism and highly variable social and mating systems . The behavioural ecology, demography and nutritional physiology of the blackbuck appear to be closely adapted to a stochastic low-resource environment and predation pressure. The chapter, based on extensive coverage of blackbuck habitats across India and intensive long-term data from a typical blackbuck habitat, elucidates these adaptations and explores links between habitat, ecology and behaviour. Blackbuck populations fluctuate mostly in response to catastrophic events, such as floods and droughts. They show high fecundity and a fast numerical response to predation and food availability. Combined predation on calves and adults by jackals, wolves and feral dogs can potentially regulate their population below nutritional carrying capacity. Predation by wolves and sex differences in mating strategies seem to shape the demographic structure of blackbuck. Male blackbuck have shorter life spans than females and males show a mortality peak in midlife corresponding to a peak in mate-competition. Blackbuck are primarily grazers and can survive on seasonally low-quality diets (crude protein  <3 %) by catabolizing proteins, and reducing movement and forage intake during summer. Blackbuck respond to an arid environment by producing concentrated alkaline urine and dry feces . However, they need to drink when forage water content is below 30 %. Blackbuck social organisation is highly variable and appears to be strongly influenced by habitat. Group sizes increase with habitat openness and resource availability. A comparison of peninsular Indian ungulates reveals that blackbuck in semi-arid grasslands show, by far, the largest group sizes. Blackbuck mating system similarly shows a close association with habitat. Like the large group sizes, the rare and spectacular lek mating system is associated with high local animal numbers and open grassland habitat. In most populations, local numbers are lower and resource-based mating territoriality is the dominant mating system. Taken together, the behaviour, nutritional ecology, breeding biology and demography of the blackbuck are suggestive of an antelope highly specialised to the shortgrass semi-arid biome.