contrary, males grow darker as the breeding season approaches. Both melanism and albinism have been observed in wild blackbuck. Albino blackbuck are often zoo attractions as in the Indira Gandhi Zoological Park (Andhra Pradesh, India). Blackbuck bear a close resemblance to gazelles, and are distinguished mainly by the fact that while gazelles are brown in the dorsal parts, blackbuck develop a dark brown or black colour in these parts. Distribution and habitat The blackbuck is native to the Indian subcontinent, but locally extinct in Pakistan and Bangladesh. In Nepal, the last surviving blackbuck population inhabits the Blackbuck Conservation Area south of Bardia National Park. In 2008, the population was estimated to comprise 184 individuals. In Pakistan, blackbuck occasionally occur along the border with India. A few blackbucks are present in the Indian Institute of Technology Madras campus. The blackbuck inhabits grassy plains and thinly forested areas where perennial water sources are available for its daily need to drink. Herds travel long distances to obtain water. The British naturalist William Thomas Blanford described the range of the blackbuck in his 1891 The Fauna of British India, including Ceylon and Burma as: Today, only small, scattered herds are seen that are largely confined to protected areas. The antelope was introduced in Texas in the Edwards Plateau in 1932. By 1988, the population had increased and the antelope was the most populous exotic animal in Texas after the chital. As of early 2000s, the population in the United States was estimated at 35,000. The blackbuck was introduced into Argentina, numbering about 8,600 individuals as of the early 2000s. Ecology and behaviour The blackbuck is a diurnal antelope, though is less active at noon when summer temperatures rise. It can run at a speed of . Group size fluctuates and seems to depend on the availability of forage and the nature of the habitat. Large herds have an edge over smaller ones in that danger can be detected faster, though individual vigilance is lower in the former. Large herds spend more time feeding than small herds. A disadvantage for large herds, however, is that traveling requires more resources. Herd size reduces in summer. Males often adopt lekking as a strategy on the part of males to garner females for mating. Territories are established by males on the basis of the local distribution of female groups, which in turn is determined by the habitat, so