The nilgai, also known as the “blue bull,” is the largest antelope native to Asia. Its common name, derived from Hindi, describes the bluish-gray coat of adult males. This mammal combines a distinctive appearance with substantial size, inhabiting both its native and introduced ranges. Though possessing traits reminiscent of deer and cattle, the nilgai is a distinct species within the antelope family.
Physical Traits
The nilgai has a sturdy, horse-like build, standing 1 to 1.5 meters (3.3 to 4.9 feet) at the shoulder. Males are significantly larger, weighing 109–288 kg (240–635 lb), while females are lighter, typically 100–213 kg (220–470 lb). Coloration shows sexual dimorphism; adult males display a bluish-gray coat, contrasted with the orange to tawny brown of females and juveniles. Both sexes have a sloping back, a deep neck, and white markings on the face, ears, and a white patch on the throat, often described as a “bib.”
Only male nilgai have horns that are short, conical, smooth, and typically black, measuring 15–24 cm (5.9–9.4 inches) in length. These horns lack the ringed structure found in many other bovids. Males also have a short crest of hair along the neck and a tuft of coarse hair, or “pendant,” below the throat patch. Their skin, particularly thick on the head and neck of males, provides defense during altercations.
Geographic Distribution
The nilgai is indigenous to the Indian subcontinent; its native range spans India, Nepal, and parts of Pakistan. Historically, they were widespread across northern India, from the Himalayan foothills to central India. They thrive in dry areas with scattered trees, grasslands, and scrub, generally avoiding dense forests and deserts.
Beyond its native habitat, the nilgai has an introduced population in the United States, particularly in Texas. They were initially brought to the U.S. as zoo attractions before the mid-1920s and released onto private ranches in South Texas around 1930. The South Texas brush country, with its dry savanna and woodland, proved ideal for their establishment and proliferation. Introduced for game animal purposes and as a potential beef supplement, a substantial free-ranging population now numbers in the tens of thousands.
Behavior and Diet
Nilgai are diurnal, active during early morning and late afternoon. They are shy and cautious, often fleeing at speeds up to 48 km/h (29 mph) when alarmed. Their social structure involves sexually segregated groups for much of the year. Females and their young form small herds of one to six individuals, while males may be solitary or gather in smaller groups. During the breeding season, peaking from December to March, males join female herds.
As herbivores, nilgai are adaptable in their feeding habits, acting as both browsers and grazers. Their diet consists of grasses and herbs, but they also consume woody plants, leaves, buds, and fruits, allowing them to forage in varied landscapes. This flexibility allows them to thrive even where domestic livestock might reduce available forage. They are known to stand on their hind legs to reach higher browse.
Ecological Role and Management
In their native habitats, nilgai are classified as “Least Concern” by the IUCN, indicating a stable population. They face localized threats, primarily from habitat loss and fragmentation due to agricultural expansion and human development. Despite protected status in some regions due to religious reverence, they are sometimes considered agricultural pests in parts of India due to crop damage.
In introduced regions like Texas, nilgai are a well-established exotic species. Their adaptation to the South Texas ecosystem has led to a population estimated between 15,000 and 50,000 individuals. They serve as a popular exotic game animal, contributing to the local economy through hunting. While coexisting with native ungulates, their presence can lead to competition for forage, particularly in areas with high cattle stocking rates, and agricultural damage. Management strategies in Texas involve regulated hunting to control populations and mitigate impacts on native species and agricultural interests.