The Nilgai is the largest antelope in Asia and is ubiquitous across the northern Indian subcontinent. It is the sole member of the genus Boselaphus. The Nilgai is the only one of the four Indian antelopes that are still abundant.
A sturdy thin-legged antelope, the nilgai is characterised by a sloping back, a deep neck with a white patch on the throat, a short mane of hair behind and along the back ending behind the shoulder, and around two white spots each on its face, ears, cheeks, lips, and chin. The nilgai, however, is more horse-like than cowlick. On the other hand, it has a hock-length cow’s tail that ends in a black tuft. Both sexes have similar markings; white areas include the cheek spots, ear tips, large throat bib, brisket, belly, rump patch, and underside of the tail. Its lower legs are banded black and white.
The ears, tipped with black, are 15–18 cm long. A column of coarse hair, known as the “pendant” and around 13 cm long in males. The tufted tail, up to 54 cm has a few white spots and is tipped with black. The forelegs are generally longer and the legs are often marked with white “socks”. While females and juveniles are orange to tawny, males are much darker – their coat is typically bluish-grey.
The ventral parts, the insides of the thighs and the tail are all white. A white stripe extends from the underbelly and broadens as it approaches the rump, forming a patch lined with dark hair. Males have thicker skin on their heads and neck that protect them in fights. The coat is not well-insulated with fat during winter, and consequently severe cold might be fatal for the nilgai. Males are horned, and the occasional female. The horns are 15–24 cm long but generally shorter than 30 cm. Smooth and straight, these may point backwards or forward. The horns of the nilgai lack the ringed structure typical of those of other bovids.
The nilgai is endemic to the Indian subcontinent: major populations occur in India, Nepal, and Pakistan. Significant numbers occur in the Terai lowlands in the foothills of the Himalayas; the antelope is abundant across northern India. It prefers areas with short bushes and scattered trees in scrub forests and grassy plains. They are common in agricultural lands but hardly occur in dense woods. In southern Texas, it roams in the prairies, scrub forests and oak forests. Though sedentary and less dependent on water, nilgai may desert their territories if all water sources in and around it dry up.
The nilgai is found feeding peaks at dawn, in the morning, in the afternoon and during the evening. Females and juveniles do not interact appreciably with males, except during the mating season. Groups are generally small, with ten or fewer individuals, though groups of 20 to 70 individuals can occur at times. However, three distinct groupings are formed: one or two females with young calves, three to six adult and yearling females with calves, and male groups with two to 18 members. Fights take place in both sexes and involve pushing their necks against each other or ramming into one another using horns. Fights can be gory; despite the protective skin deep, lacerated wounds and even deaths might occur. The nilgai is a browser or mixed feeder, but primarily a grazer in Texas. It prefers grasses and herbs, but also feeds on woody plants in the dry tropical forests of India. Diets generally suffice in protein and fats.
Observations of females in southern Texas revealed that ovaries are developed by two years of age and the first birth takes place typically a year later, though in a few cases, females as young as one-and-a-half years may mate successfully. Females can breed again around a year after parturition. Males in the same location were found to have active testes by the age of three years, which matured considerably by the next year. Males become sexually active at four or five years.
Mating may occur throughout the year, with peaks of three to four months. The time of the year when these peaks occur varies geographically. Males become aggressive and fight among themselves for dominance. These fights are characterised by displays of the enlarged chest, the throat patch and the beard while holding the head upright; and threatening the opponent by running with the horns pointed toward him and circling him. The victorious bull would protect the vicinity of the targeted female from other males. The courtship typically lasts for 45 minutes.
Gestation lasts eight to nine months, following which a single calf or twins (even triplets at times) are born. Calves are precocial; they can stand within 40 minutes of birth, and forage by the fourth week. Pregnant females isolate themselves before giving birth. As typical of several bovid species, nilgai calves are kept in hiding for the first few weeks of their lives. This period of concealment can last as long as a month. Calves, mainly males, bicker playfully by neck-fighting. Young males would leave their mothers at ten months to join bachelor groups. The lifespan of the nilgai is typically ten years.
• Remains of nilgai have been excavated at Pandu Rajar Dhibi in West Bengal, suggesting that they were domesticated or hunted in eastern India in the Neolithic period (6500–1400 BCE) and during the Indus Valley civilisation (3300–1700 BCE) in the Indian subcontinent.
• There is a reference to the nilgai in the Aitareya Brahmana (a Hindu religious text dated 500–1000 BCE), where one of the Prajapatis (progenitor god) is said to have assumed the form of a nilgai.
• Nilgai is extensively featured in paintings, dagger hilts and texts from the Mughal era.
• Their representation, however, is less frequent than that of horses and camels. On being disturbed while hunting nilgai, the Mughal emperor Jahangir recorded his ire.
• For centuries Indian villagers have associated the nilgai with the cow, a sacred animal revered by Hindus, and the name (“gai” means “cow” in Hindi) indicates the similarity they saw with the cow.
• Tribes such as the Bishnois traditionally take care of wild animals like the nilgai
