The Nilgai (Boselaphus tragocamelus) is one of only two species in the tribe Boselaphini, one of the three tribes in the subfamily Bovinae (the other species in this tribe is the much smaller Chowsingha, Tetracerus quadricornis). Nilgai are native to northeastern Pakistan, lowland areas of southern Nepal, and peninsular India. They have been successfully introduced to Italy near Rome (but were extirpated there during World War II), South Africa, the southern United States (Texas), and northern Mexico.
In their native range in India and Nepal, Nilgai prefer level to rolling terrain with scattered short trees and brush interspersed with open grasslands. They are rarely found in dense forest. Although Nilgai are mainly crepuscular, they can be active throughout the day and night (they sometimes raid agricultural fields at night). In both their native range and in Texas the distribution of Nilgai is limited by the availability of drinking water.
Females are typically sexually mature at two years. Twins are common (accounting for around 50% of births in southern Texas, with occasional triplets). Males may be sexually mature at three years, but males of 4 to 5 years are the most active breeders. During the breeding season, males may fight and serious injuries are not uncommon.
Only male Nilgai have horns. These are typically short, black, smooth, and nearly straight. Both sexes have tails that are white below and white patches on the throat, cheeks, and lips, as well as a white ring above and a white ring below the .
Globally, Nilgai populations are secure. There are around 100,000 Nilgai in India and a handful in Pakistan; they have been extirpated from Bangladesh. The introduced population in southern Texas includes around 37,000 individuals.
: Leo Shapiro