Thenilgai (Boselaphus tragocamelus) (/ˈnilˌɡaɪ/, literally meaning "blue cow") is the largestantelope ofAsia, and is ubiquitous across the northern Indian subcontinent. It is the sole member of thegenusBoselaphus, which was firstscientifically described byPeter Simon Pallas in 1766. The nilgai stands 1–1.5 m (3.3–4.9 ft) at the shoulder; males weigh 109–288 kg (240–635 lb), and the lighter females 100–213 kg (220–470 lb). 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 crest of hair along the neck terminating in a tuft, and white facial spots. A column of pendant coarse hair hangs from the dewlap ridge below the white patch.Sexual dimorphism is prominent – while females and juveniles are orange to tawny, adult males have a bluish-greycoat. Only males possesshorns, 15–24 cm (5.9–9.4 in) long.
The nilgai isdiurnal (active mainly during the day). The animals band together in three distinct kinds of groups: one or two females with young calves, three to six adult and yearling females with calves, and all-male groups with two to 18 members. Typically tame, the nilgai may appear timid and cautious if harassed or alarmed; it flees up to 300 m (980 ft), or even 700 m (2,300 ft), galloping away from the source of danger. Herbivores, nilgai prefer grasses and herbs, though they commonly eatwoody plants in the dry tropical forests of India. Females becomesexually mature by two years, while males do not become sexually active until four or five years old. The time of the year when mating takes place varies geographically, but a peak breeding season lasting three to four months can be observed at most places.Gestation lasts eight to nine months, following which a single calf (sometimes twins or even triplets) is born. As typical of several bovid species, nilgai calves stay hidden for the first few weeks of their lives. The lifespan of the nilgai is around ten years.
The nilgai prefers areas with short bushes and scattered trees inscrub forests and grassy plains. It is commonly found on agricultural land and rarely in dense forests. Major populations occur in the Indian and NepalTerai. It was thought to be extinct inBangladesh. The nilgai was introduced toTexas in the 1920s to 1930s. As of 2008,[update] the feral population in Texas is nearly 37,000[citation needed]. The nilgai is categorised asLeast Concern on theIUCN Red List.[3] The nilgai has been associated withIndian culture since theVedic period (1500–500 BCE). They were hunted in theMughal era (16th to 19th centuries) and are depicted in numerous miniatures. Nilgai have been considered a pest in severalnorth Indian states, as they ravage crop fields and cause considerable damage. InBihar, authorities have classified the nilgai asvermin[citation needed].
The vernacular name "nilgai"/ˈnɪlˌɡaɪ/ comes from the fusion of the Hindi wordsnil ("blue") andgai ("cow"). The word was first recorded in use in 1882.[7] Alternative origins could be from the Persiangaw ("cow").[2] The nilgai has been referred to by a variety of names: neelghae,[2] nilgau, nilgo,[1] nylghau,[8] and nylghai,[9] constructions referring to other "blue" animals. They are also known as white-footed antelope.[2] DuringMughal emperorAurangzeb's reign of India, the nilgai was known by the namenilghor ("nil" for "blue" and "ghor" for "horse").[10]
The generic nameBoselaphus comes from the combination of the Latinbos ("cow" or "ox") and the Greekelaphos ("deer").[11] The specific nametragocamelus is derived from the joining of the two Greek wordstragos ("he-goat") andkamelos ("camel"). The binomial combination was first used by English zoologistPhilip Sclater in 1883.[2]
Though the tribe Boselaphini has no African representation today,[14]fossil evidence supports its presence in the continent in the prehistoric times, as early as the lateMiocene. The two living antelope species of this tribe have been found to have a closer relationship with the earliest bovids (likeEotragus species) than do the other bovids.[9][15] This tribe originated at least 8.9 million years ago, in much the same area where thefour-horned antelope lives today, and may represent the most "primitive" of all living bovids, having changed the least since the origins of the family.[16] The extant and extinct boselaphine forms show similar development of thehorn cores (the central bony part of the horn).[17] Though the extant nilgai females lack horns, historic relatives of the antelope had horned females.[18] Fossil relatives were once placed in the subfamily Cephalophinae[19] which now contains only the Africanduikers.[20] Fossils ofProtragoceros andSivoreas dating back to the late Miocene have been discovered not only in Asia and southern Europe but also in theNgorora Formation (Kenya) and are thought to belong to the Boselaphini.[18][21] Other Miocene fossils of boselaphines discovered are ofEotragus,Miotragocerus andTragoportax; fossils ofMiotragoceros are not apparent in Africa (onlyM. cyrenaicus has been reported from the continent), but have significant presence in theShiwalik Hills inIndia andPakistan, as do severalTragoportax species. A 2005 study showed the migration ofMiotragoceros to eastern Asia around eight million years ago.[22] Alan W. Gentry of theNatural History Museum reported the presence of another boselaphine,Mesembriportax, fromLangebaanweg (South Africa).[23]
Remains of the nilgai dating back to thePleistocene have been discovered from theKurnool caves in southern India.[24] Evidence suggests that they were hunted by humans during theMesolithic period (5,000 to 8,000 years ago).[25][26]
Close view of a male nilgai showing the facial markings, throat patch, beard and short hornsSkull of a nilgai
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.[10] The ears, tipped with black, are 15–18 cm (5.9–7.1 in) long.[2] A column of coarse hair, known as the "pendant" and around 13 cm (5.1 in) long in males, can be observed along the dewlap ridge below the white throat patch.[27] The tufted tail, up to 54 cm (21 in),[28] has a few white spots and is tipped with black.[10] The forelegs are generally longer,[28] and the legs are often marked with white "socks".[2]While females and juveniles are orange to tawny, males are much darker – theircoat is typically bluish grey. Theventral parts, the insides of the thighs and the tail are all white.[28] A white stripe extends from the underbelly and broadens as it approaches therump, forming a patch lined with dark hair.[27] Almost white, though notalbino, individuals have been observed in theSariska National Park.[29] while individuals with white patches have been recorded at zoos.[30] The hairs, typically 23–28 cm (9.1–11.0 in) long, are fragile and brittle.[31] Males have thicker skin on their head and neck that protect them in fights.[10] The coat is not well-insulated with fat during winter, and consequently severe cold might be fatal for the nilgai.[32]Males are horned, and the occasional female. The horns are 15–24 cm (5.9–9.4 in) long but generally shorter than 30 cm (12 in).[10] Smooth and straight, these may point backward or forward.[33] The horns of the nilgai lack the ringed structure typical of those of other bovids.[34]
The nilgai is the largest antelope in Asia.[10][35] It stands 1–1.5 m (3 ft 3 in – 4 ft 11 in) at the shoulder;[27] the head-and-body length is typically between 1.7–2.1 m (5 ft 7 in – 6 ft 11 in).[10] Males weigh 109–288 kg (240–635 lb); the maximum weight recorded is 308 kg (679 lb). Females are lighter, weighing 100–213 kg (220–470 lb).[27]Sexual dimorphism is prominent; the males are larger than females and differ in colouration.[2]
The maximum recorded length of the skull is 376 mm (14.8 in). Thedental formula is0.0.3.33.1.3.3. Themilk teeth are totally lost and thepermanent dentition completed by three years of age. The permanent teeth get degraded with age, showing prominent signs of wear at six years of age. The nilgai has sharp ears and eyes,[36] though its sense of smell is not as acute.[37]
The nilgai isendemic to theIndian subcontinent: major populations occur inIndia,Nepal andPakistan. The population inBangladesh was thought to be extinct, but some individuals from Indian and Nepalese populations cross the border into the northwest of the country.[38][39] Significant numbers occur in theTerai lowlands in the foothills of theHimalayas; the antelope is abundant across northern India.[40]It prefers areas with short bushes and scattered trees inscrub 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 andoak forests. It is ageneralist animal—it can adapt to a variety of habitats.[2] Though sedentary and less dependent on water, nilgai may desert their territories if all water sources in and around it dry up.[41] Territories in Texas are 0.6 to 8.1 square kilometres (0.23 to 3.13 sq mi) large.[2]
The Indian population was estimated at one million in 2001.[1] The nilgai were first introduced toTexas in the 1920s and the 1930s in a 6,000 acres (2,400 ha) large ranch near the Norias Division of theKing Ranch, one of the largest ranches in the world. The feral population saw a spurt toward the latter part of the 1940s, and gradually spread out to adjoining ranches.[42]
Nilgai search for new areas if they run out of water
Population densities show great geographical variation across India. Density can be as low as 0.23 to 0.34 individuals per km2 inIndravati National Park.[43] and 0.4 individuals per km2 in thePench Tiger Reserve,[44] or as high as 6.6 to 11.36 individuals per km2 in Ranthambhore National Park, and seven individuals per km2 inKeoladeo National Park.[45] Seasonal variations were noted inBardiya National Park in a 1980 study; the density 3.2 individuals per km2 during the dry season and 5 per km2 in April, the start of the dry season.[46] In southern Texas, densities were found to be nearly 3–5 individuals per km2 in 1976.[2]
Historic notes mention nilgai in southern India, but these may have been feral:[47]
I believe that the Coimbatore and Salem collectorates are almost the only places in Southern India, in which nil-gai are to be found. It is difficult to account for the animals being thus so widely divided from their usual haunts unless as has been generally supposed, these Southern specimens are the progeny of a semi-domesticated herd, which, at some by-gone period, had escaped from the preserve of a native potentate.
— Andrew Cooke McMaster (Notes on Jerdon's Mammals of India, 1871)
The nilgai isdiurnal (active mainly during the day). A 1991 study investigated the daily routine of the antelope and found feeding peaks at dawn, in the morning, in the afternoon and during the evening.[48] 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.[27] In a 1980 study inBardiya National Park, the average herd size was of three individuals;[46] In a 1995 study in theGir National Park, herd membership varied with season.[49] 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.[50]
Typically tame, the nilgai may appear timid and cautious if harassed or alarmed; instead of seeking cover likeduikers it would flee up to 300 m (980 ft)-or even 700 m (2,300 ft) on galloping-away from the danger.[41] Though generally quiet, nilgai have been reported to make short guttural grunts when alarmed, and females to make clicking noises when nursing young.[50][51] Alarmed individuals, mainly juveniles below five months, give out a coughing roar (whose pitch is highest in case of the juveniles) that lasts half a second, but can be heard by herds less than 500 m (1,600 ft) away and responded to similarly.[2]
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.[2]Display behaviour focuses on the throat patch and the beard, and threatening opponents by pointing the horns toward them. A young male was observed making a submissive display in the Sariska Reserve by kneeling before an adult male, who stood erect.[50] The nilgai mark their territories by forming dung piles as much as 50 cm (20 in) in radius. The defecation process is elaborate-the antelope stands with his legs about a metre apart, with the rump lowered and the tail held almost vertical; it stays in the same posture for at least ten seconds after relieving itself. The process is not as elaborate in the females as it is in the males.[41]
The nilgai is abrowser[46] or mixed feeder,[55] but primarily a grazer in Texas.[41] It prefers grasses and herbs, but also feeds onwoody plants in the dry tropical forests of India. Diets generally suffice in protein and fats.[56] The protein content of the nilgai's should be at least seven percent.[57] The nilgai can survive for long periods without water and does not drink regularly even in summer.[2][58]
A herd of nilgai grazing inKeoladeo National Park, RajasthanNilgai can reach for high branches
Observations of females in southern Texas revealed thatovaries 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.[27] Females can breed again around a year after parturition.[2] Males in the same location were found to have activetestes by the age of three years, thatmatured considerably by the next year.[63] 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. In Texas, a peak is apparent from December to March.[32] InBharatpur National Park, the breeding season is from October to February, peaking in November and December. Sariska reserve witnesses a similar peak in December and January.[50]In the mating season,rutting males move about in search of females inoestrus.[50] Males become aggressive and fight among themselves fordominance. 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.[41][64] The victorious bull would protect the vicinity of the targeted female from other males. The courtship typically lasts for 45 minutes. The male, stiff and composed, approaches the receptive female, who keeps her head low to the ground and may slowly walk forward. The male licks her genitalia, upon which the female holds her tail to a side and the male gives out aflehmen response. Finally, the male pushes his chest against her rump, and mounts her.[41]
Gestation lasts eight to nine months, following which a single calf or twins (even triplets at times) are born. In a 2004 study in the Sariska reserve, twins accounted for as high as 80 percent of the total calf population.[50] Births peak from June to October in the Bharatpur National Park, and from April to August in southern Texas. Calves are precocial; they are able to stand within 40 minutes of birth, and forage by the fourth week.[10] 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 in Texas.[41] Calves, mainly males, bicker playfully by neck-fighting.[48] Young males would leave their mothers at ten months to join bachelor groups.[28] The lifespan of the nilgai is typically ten years in Texas.[27]
The nilgai is categorised as ofLeast Concern by the International Union for the Conservation of Nature and Natural resources (IUCN).[1] While it is common in India, the nilgai occurs sparsely in Nepal and Pakistan.[40] The major reasons behind its decimation in these two countries are rampant hunting, deforestation and habitat degradation in the 20th century. As of 2008, the feral population in Texas was nearly 37,000.[1] Wild populations also exist in the US states ofAlabama,Florida andMississippi and the Mexican state ofTamaulipas, where they have escaped from private exotic ranches.[citation needed] The population around the Texas-Mexico border is estimated to be around 30,000 (as of 2011).[65]
Prajapati desired his own daughter ... Having become a nilgai bull he approached her who had become a nilgai cow ... The gods saw him and said: "Prajapati is doing a deed that is not done".
Nilgai are extensively featured in paintings, dagger hilts and texts from theMughal era (16th to 19th centuries);[72][73] their representation, however, is less frequent than that of horses and camels.[74] On being disturbed while hunting nilgai, the Mughal emperorJahangir recorded his ire:[75]
Suddenly a groom and two bearers appeared, and the nilgai escaped. In a great rage, I ordered them to kill the groom on the spot and hamstring the bearers and mount them on asses and parade them through the camp.
For centuries Indian villagers have associated the nilgai with thecow, a sacred animal revered byHindus, and the name ("gai" means "cow" in Hindi) indicates the similarity they saw with the cow.[28][76] The nilgai is rarely consumed by Hindus due to its religious significance. Tribes such as theBishnois traditionally take care of wild animals like the nilgai.[77] The nilgai was not widely hunted until the 20th century, when habitat degradation and poaching became rampant.[78][79][self-published source] The meat of nilgai is said to be lighter and milder flavoured thanblackbuck meat.[33][80]
The populations of nilgai in India are so large that farmers in the states ofBihar,Chhattisgarh,Haryana,Madhya Pradesh,Maharashtra,Rajasthan andUttar Pradesh have pleaded to the government to cull them. Nilgai herds raid and trample crop fields across these states,[81] often causing food shortages.[82][83]Farmers use live electric wires to guard their farms, which kills other animals as well.[84] Farmers inNeemuch (Madhya Pradesh) went on a hunger strike in 2015 demanding compensation for the damage caused by nilgai.[85] Although blackbuck cause a similar problem, the damage caused by them is significantly lower as they merely break off young shoots.[86][87] A 1990 study suggested culling, building enclosures for the antelopes and fencing off agricultural areas as remedies.[86]
The governments of Bihar,[82] Maharashtra[88] andUttarakhand[89] have urged theGovernment of India to declare the nilgai asvermin; the proposal has been implemented in Bihar, where nilgai can now be hunted to minimise the damages incurred by locals.[82] TheUttar Pradesh government has given farmers and firearm licence holders the right to cull the animals.[90] However, animal rights activists in various parts ofIndia were unhappy with the decision.[91] Shivanshu K. Srivastava, acolumnist andsocial activist, wrote that "The culling of nilgais (blue bulls) in Bihar in July 2016 was so deplorable that it doesn't need any justification. The excuse given for this slew by the State government, the then environment minister Prakash Javadekar and the judiciary is so illogical that it mocks all the solutions available to stop the nilgais from destroying the farms. We live in the 21st century and culling is only the very last option we have. The farmers can either opt for fencing around the farmlands or if it's unaffordable, then the government can give ordinances to relocate them to the forests."[92][93] The state governments have attempted other initiatives to curb the nilgai: in November 2015, theGovernment of Rajasthan came up with a proposal to allow shooting nilgai with non-lethal darts to inhibitfertilisation in their bodies, so as to regulate their increasing populations.[94] As the name "nilgai" appeals to the religious sentiments of Hindus, theGovernment of Madhya Pradesh has sought to officially rename itrojad (Hindi for "forest antelope") and the Government of Haryana to rename it asroze in a bid to make their culling acceptable.[95][96][97]
A 1994 study drew attention to the ecological value provided by the nilgai inravines lining theYamuna River. In summer, the faeces of the antelope contained nearly 1.6 percent nitrogen, that could enhance the quality of the soil up to a depth of 30 cm (12 in). Seeds in the droppings could easily germinate and assist in afforestation.[98]
In September 2019, a video surfaced of a nilgai being buried alive with an excavator in Bihar as part of the culling. The state forest department has claimed to have begun an investigation to find those responsible.[99]
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