Boselaphus tragocamelusnilgai

Geographic Range

Boselaphus tragocamelus, also called the nilgai antelope, evolved in penninsular India during the Tertiary geological period, where they are also currently found. They were imported to the United States as zoo animals before the mid-1920s and released into Texas about 1930. Today they are found on large ranches in Kenedy and Willacy counties of Texas.

Habitat

Nilgai antelopes live in dry areas with a variety of land types. They range from grassy, steppe woodlands, to hillsides. In India, they occur in the foothills of the Himalayan Mountains southward to Mysore. The brush country of South Texas is well suited to their natural preferences.

Physical Description

Nilgai antelope are among the largest of the asian antelopes. They stand about 120-150cm at the shoulder and have a body length of 180-200cm. They have a short coat which is yellow-brown in females and turns blue-grey in adult males. Calves are pale brown. The hair of the adult nilgai antelope is thin and oily, but the skin is thick on the chest and neck of the males. There are patches of white on the face and below the chin. This extends into a broad, white "bib" on the throat. In males below the "bib" hangs a tuft of hair, or "beard" that can be as long as 13cm.

A white band along the brisket area goes over the abdomen and spreads between the hind legs, which forms a narrow rump patch that is outlined with darker hair. They have slender legs which support their stocky bodies. The head is long and slender and males have horns about 20-25cm, which are black in color, sharp, and curved.

  • Range mass
    120 to 240 kg
    264.32 to 528.63 lb

Reproduction

Females and males remain segregated for most of the year, except for when the bulls join the cows for breeding. Breeding groups consist of one dominant bull and one to many cows. Mating usually occurs from December to March, but breeding can occur through the year. The gestation period is 240-258 days and it is common for nilgai antelopes to bear twins. Females can conceive at 18 months of age, but very few mate before 3 years of age. Males are sexually mature by 2 1/2 years of age, but cannot compete very well with other males until 4 years of age.

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • Range number of offspring
    1 to 2
  • Average number of offspring
    1.3
  • Average number of offspring
    1.5
    AnAge
  • Range gestation period
    8.27 to 8.6 months
  • Average gestation period
    8.435 months
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    815 days
    AnAge
  • Parental Investment
  • altricial
  • post-independence association with parents

Lifespan/Longevity

Behavior

Nilgai antelopes are usually found in herds of about 10 animals, but larger groups of 20 to 70 have been seen. They are dinural with most activity in the early morning and late afternoon. They have good eyesight and hearing that is equal to or better than the white-tail deer, but they do not have a good sense of smell. Though they are normally silent, they can make a roaring like vocalization when alarmed. When chased they can reach speeds up to 29 mph.

Communication and Perception

Food Habits

Nilgai antelopes graze and browse, with grass as the main source of their diet. In Asia, they eat mainly woody plants. In Texas, they eat mesquite, oak, partridge peas, croton, nightshade, and a variety of grasses. Sometime they upgrade their diet by eating plant parts, such as flowers, seeds, fruits, leaves, and stem tops.

Economic Importance for Humans: Positive

The nilgai antelope is hunted for its meat. Overhunting may negatively impact populations of nilgai antelope.

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

Nilgai antelope may damage human food crops in the areas in which they are found.

Conservation Status

Hunting by humans threatens nilgai antelopes.

Other Comments

The nilgai antelope was first described by Pallas in 1766. Nilgai is from the Hindi word nilgaw which means "blue bull" referring to the color of the adult male. The species name, Boselaphus tragocamelus is derived from 'bos', Latin for ox, 'elaphos', Greek for deer, 'tragos', Greek for a male goat, and 'kamelos', Greek for camel.

Contributors

Melody Benton (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

food

A substance that provides both nutrients and energy to a living thing.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5? N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

References

1990. Grzimek's Encyclopedia of Mammals. New York, New York: McGraw Hill.

1994. "The Mammals of Texas-Online Edition (Nilgai)" (On-line). Accessed November 17, 1999 at http://www.nsrl.ttu.edu/tmot/bosetrag.htm.

Huffman, B. "Nilgai (Boselaphus tragocamelus)" (On-line). Accessed November 17, 1999 at http://www.pathcom.com/~dhuffman/nilgai.html.

Nowak, R. 1991. Walker's Mammals of the World (Fifth Edition). Baltimore, Maryland: John Hopkins University Press.

Sheffield, W. 1997. "The Handbook of Texas Online (Nilgai Antelope)" (On-line). Accessed November 17, 1999 at http://www.tsha.utexas.edu/handbook/online/articles/view/NN/tcn1.html.