Indian rhinoceroses (Rhinoceros unicornis) were historically found across the northern part of the Indian subcontinent - as far west as Pakistan and as far east as Bangladesh. They once lived throughout the northwestern Oriental region and the southeastern Palearctic region, along the Indus River Valley. Today, the geographic distribution of wild Indian rhinoceroses is limited to northeastern India and some parts of southern Nepal.
Most Indian rhinoceroses live within the boundaries of national parks. Indian rhinoceroses living in Chitwan National Park, one of the primary conservation regions for their species, have divided into four distinct subpopulations that are separated by physical barriers, such as low mountains and rivers. Kaziranga National Park, located in northern India, hosts the largest population of Indian rhinoceroses compared to other national parks, with over 2,000 individuals. There are a total of eight national parks across the northern Indian subcontinent where Indian rhinoceroses live. (Laurie, et al., 1983; Sinha, 2011; Talukdar, et al., 2014; Thapa, et al., 2014)
Indian rhinoceroses are most commonly found in tropical and temperate regions of southern Nepal and northeast India. They are most frequently observed in wet alluvial plain grasslands and are seen wallowing and bathing in adjacent rivers and pools. They also live in dry savanna grasslands and eastern Himalayan deciduous forests. Indian rhinoceroses also occasionally use swamp-forests during the rainy season, although they typically stay in alluvial plain grasslands throughout the year.
Wet alluvial grassland and dry savanna habitats, such as those in Orang National Park, located on the north bank of the Brahmaputra River in northern India, are most suitable for Indian rhinoceroses. These habitats are found less than 50 m above sea level, within 500 m of a body of water, and more than 200 m away from the nearest roads. Grasslands and eastern seasonal swamp forests are moderately suitable for Indian rhinoceroses, and can be found from 40 to 60 m above sea level. Occasionally, Indian rhinoceroses are found in woodlands up to 70 m above sea level, but this habitat is less suitable for Indian rhinoceroses compared to those mentioned previously. Habitat suitability is influenced by food availability, distance from human development, and proximity to bodies of water. (Nowak, 1999; Sarma, et al., 2011; Talukdar, et al., 2014; Tripathi, 2012)
Indian rhinoceroses are large quadruped mammals with gray-brown skin. Their skin has numerous folds around their legs and rears, which gives them the appearance of wearing armor. The skin around their folds has a pinkish hue. Indian rhinoceroses can be distinguished from their African relatives by their folds and the presence of a single horn at the end of the snout, rather than two horns.
Male Indian rhinoceroses are larger than females on average and also have large neck folds that are absent or reduced in females. Adult males are 3.7 to 3.8 m long and weigh 2,200 kg on average. Females are 3.1 to 3.4 m long and weigh 1,600 kg on average. At their shoulders, males measure 1.70 to 1.86 m tall and females measure 1.48 to 1.73 m tall. All Indian rhinoceroses, regardless of sex, have a single black horn with an average length of 529 mm. Their horns are, on average, 185 mm wide at the base and quickly become narrower before coming to a point. Their tails are 70 to 80 cm long on average, and average body temperature is 37.4 ºC.
At birth, calves weigh 40 to 81 kg and are 0.97 to 1.22 m long, with a shoulder height of 0.56 to 0.67 m. Within one month, calves reach double their birth weight, and fter one year they reach nearly ten times their initial birth weight. At birth and as juveniles, Indian rhinoceroses lack skin folds and their horns are either small or absent. These features develop as they approach adulthood. Juvenile development tends to be slower in the wild than in captivity. (Clauss, et al., 2004; Laurie, et al., 1983; Nowak, 1999; Weigl, 2005)
Indian rhinoceroses do not have a specific mating season. They are polygynandrous, meaning both males and females have multiple mates. Female Indian rhinoceroses indicate their reproductive availability and readiness by urinating frequently and whistling loudly. These signals typically attract interested males within 8 to 10 hours. Males taste the urine that females leave behind to confirm their estrous state. Males respond to reproductively active females with precopulatory behavior, such as prolonged chases of 1 to 2 kilometers. These behaviors ensure that males are physically fit and that they are likely dominant bulls.
Aside from copulatory interactions, Indian rhinoceroses are solitary. The only time that males are aggressive towards other males is when they are defending their mate and their territory - which they only establish while attempting to attract mates. Mating pairs separate from one another after reproduction and exhibit no fidelity to previous mates during subsequent breeding seasons. (Hutchins and Kreger, 2006; Nowak, 1999; Schaftenaar, et al., 2011; Tripathi, 2013; Weigl, 2005; Zschokke and Baur, 2002)
Indian rhinoceroses breed throughout the year and do not have a specific breeding season. Their breeding interval is, on average, 850 days. Females gives birth to a single live young after 425 to 496 days of gestation.
Indian rhinoceroses give birth to one offspring at a time. Newborns typically weigh 40 to 81 kg at birth, with an average of 64.5 kg. For 12 to 18 months following birth, infants get their nutrition from milk that their mothers produce, after which they transition to a diet of grasses, shrubs, and fruit similar to that of adults. It takes 6.5 to 10 years for juvenile Indian rhinoceroses to become independent of their mothers. Female rhinoceroses tend to reach reproductive maturity at 4 to 5 years of age, while male rhinoceroses reach reproductive maturity at 7 to 8 years of age. (Nowak, 1999; Schaftenaar, et al., 2011; Tripathi, 2012; Weigl, 2005; Zschokke and Baur, 2002)
Male Indian rhinoceroses exhibit no parental investment beyond the act of mating. Conversely, females care for their young for an extended period of time. Juvenile Indian rhinoceroses are not fully weaned until they are 12 to 18 months old, and they remain with their mothers for 6.5 to 10 years before they reach independence.
Females tend to have reduced appetites immediately after giving birth, and they also tend to seclude themselves in dense vegetation. By decreasing their activity and isolating themselves, females can allocate more energy to producing milk for infants and form a bond with their offspring without interference. Furthermore, reclusive behavior likely decreases the chances of their offspring being injured by other, mature Indian rhinoceroses and also reduces the likelihood of predation. As soon as calves can walk, they look for their mothers to begin nursing. Once calves have reached 6 or 7 years of age, they become less dependent on their mothers and the two gradually spend less time together. (Nowak, 1999; Schaftenaar, et al., 2011; Tripathi, 2013; Weigl, 2005; Zschokke and Baur, 2002)
There is no average lifespan for Indian rhinoceroses in the wild or in captivity, though they are expected to live a maximum of 40 years in the wild. There is one case of a captive rhino living as long as 47 years, but the legitimacy of this record is under dispute. One wild-born male died in captivity after living 43 or 44 years. Three other individuals have lived longer than 40 years in captivity.
Recent research shows that rhinoceroses who are sensitive to humans - such as the ones that do not live in a frequently visited national park or zoo - are more likely to have a shorter lifespan due to excessive stress after abrupt human exposure. Stress weakens their immune systems, which leaves them more susceptible to disease. (Nowak, 1999; Weigl, 2005)
Indian rhinoceroses are typically solitary with the exception of breeding season, when males and females interact to mate. Once they have successfully bred, adult males typically distance themselves from females using olfactory cues. During breeding season, adult males defecate and urinate to mark their territories. Indian rhinoceroses use olfactory communications extensively, so the presence of dung and urine from other individuals tend to drive Indian rhinoceroses away from a given area.
Although Indian rhinoceroses are generally solitary, females remain in close contact with their calves for up to 10 years. The lack of social contact with rhinoceroses leads to little or no true competition between breeding and non-breeding bulls. Individuals usually run away from disturbances rather than attack. However, breeding bulls will aggressively compete for territory, engaging in agonistic displays such as charges, horn clashes, and lunges.
Indian rhinoceroses are active mostly in the late afternoon, early morning, and at night. They are typically observed foraging or wallowing in ponds, swamps, or other bodies of water. Wallowing helps rhinoceroses thermoregulate and prevents dehydration from overexposure to the sun. Wallowing also repels biting insects and external parasites. Indian rhinoceroses sometimes scratch and rub their skin against trees or other vegetation, which is thought to be both a comfort and maintenance behavior that helps them shed dead skin cells. During the dry season, when bodies of water are less abundant, Indian rhinoceroses spend most of their day grazing underneath shade provided by vegetation. (Hutchins and Kreger, 2006; Laurie, et al., 1983; Nowak, 1999; Tripathi, 2012; Tripathi, 2013; Weigl, 2005)
Indian rhinoceroses typically have home ranges of 2 to 8 km². The home ranges of males occasionally overlap with those of females, though this is uncommon. Breeding males establish territories 1 to 4 km² large. (Laurie, et al., 1983; Nowak, 1999; Sinha, 2011)
Indian rhinoceroses use a variety of noises to communicate with one another. Adults use snorts as initial contact calls. Calves emit quick grunts to call their mothers. Encounters between two rhinos - often reproductive males - can result in prolonged agonistic displays, which involve honking, bleating, and roaring in hostility towards each other. Indian rhinoceroses also scream or pant when there are indications of possible danger.
Indian rhinoceroses also communicate using scents that are carried in urine, dung, and sweat glands. Indian rhinoceroses all defecate into communal dung heaps called middens. Individuals smell middens before defecating in them to determine the presence of other individuals at gathering areas such as bodies of water or popular feeding areas.
Adult males convey interest in females by making a furrow-like pathway of three parallel lines in the ground. They do this by urinating in jets behind them while dragging their hind legs.
Indian rhinoceroses communicate extensively using body language. For example, warn each other of predators or other threats by flattening their ears. They also rub their bodies together to show affection towards one another. Calves will show interest in interacting playfully with other calves by swinging their heads side to side. (Cave, 2009; Laurie, et al., 1983; Nowak, 1999)
Indian rhinoceroses are generalist herbivores that need approximately 150 to 200 kg of food each day. They graze during the early morning, late afternoon, and throughout the night. They most commonly eat grasses, but they also eat flowers, fruit, twigs and branches, and grains such as rice (Oryza sativa).
During the dry season, grasses make up the majority of the diets of Indian rhinoceroses. They eat terrestrial plants like Bermuda grass (Cynodon dactylon) and aquatic plants like giant cane (Arundo donax). They also occasionally consume twigs and branches of deciduous trees, such as crepe myrtle (Lagerstroemia indica).
During monsoons, because terrestrial grasses are often submerged in water, Indian rhinoceroses tend to consume plants that grow taller, such as Indian timber bamboo (Bambusa tulda) or sacred fig (Ficus religiosa). Indian rhinoceroses can dive underwater to eat submerged grasses, but tend to feed on taller reeds and trees that remain above water.
Indian rhinoceroses consume grasses and low leaves by curling their upper lips around the stems and pulling them off the ground. They have flat molars with grooves that are adapted to grind plant matter. (Hazarika and Saikia, 2012; Konwar, et al., 2009; Nowak, 1999; Thapa, et al., 2014; Tripathi, 2012)
The main predators of Indian rhinoceroses are humans (Homo sapiens). From the late 18th century to the early 19th century, Indian rhinoceroses were hunted for sport, for their horns, and to prevent them grazing crops. During the early 19th century, there was a booming interest in using alluvial plain grasslands as agricultural lands. Humans quickly wiped out Indian rhinoceroses living in these grasslands in order to clear the habitat for farming grounds and related development projects.
Rarely, Bengal tigers (Panthera tigris tigris) hunt young calves or sick adults. However, Indian rhinoceroses are a relatively uncommon portion of the diet of Bengal tigers.
Indian rhinoceroses use their horns to defend themselves. The sharp, pointed tips at the end of their horns can be used to intimidate or harm potential predators. (Hutchins and Kreger, 2006; Nowak, 1999; Talukdar, et al., 2014)
Indian rhinoceroses feed on grasses, shrubs, and small trees, and likely play a role in controlling understory growth and forest succession. Indian rhinoceroses are hosts for multiple parasites, including leeches (subclass Hirudinea), ticks (Dermacentor auratus), gut nematodes (genus Decrusia), and bloodsucking flies in the genus Tabanus. Birds such as common myna birds (Acridotheres tristis) and cattle egrets (Bubulcus ibis) pick off and feed on parasitic invertebrates that are attached to the skin folds or around the feet of Indian rhinoceroses. Bengal tigers (Panthera tigris tigris) prey on calves that are up to 6 months old. (Laurie, et al., 1983)
Indian rhinoceroses are valuable economically. Their horns have increased in value from $35 per kg in 1972 to about $18,000 per kg in 1991. Their horns are used as an ingredient in traditional Chinese medicines, where they are ground into a fine powder and mixed with other herbs to help reduce the temperature of people with fever-like symptoms. Their horns have also historically been used as ceremonial dagger handles and as material from which figurines were carved.
There are also several reports of Indian rhinoceroses being tamed and trained to work, performing jobs such as pulling ploughs, performing tricks at circuses, and even carrying loads of laundry for a local washerman on his delivery rounds. Ancient kings of India reportedly used Indian rhinoceroses for battle as both a mount and a ramming weapon.
Indian rhinoceroses are also kept in many zoos to increase public awareness and educate people on their conservation needs and life history. (Laurie, et al., 1983; Nowak, 1999; Weigl, 2005)
Indian rhinoceroses reportedly kill several people in India and Nepal each year. Most of these deaths were attributed to Indian rhinoceros females with young calves. (Nowak, 1999; Talukdar, et al., 2014)
Indian rhinoceroses are listed as "vulnerable" on the IUCN Red List and are under Appendix I of CITES, which prevents international trade for any reason other than research.
Since the 18th century, Asian hunters have poached Indian rhinoceroses for their horns. Because their horns are composed of tough keratin proteins, many products are made from it. Examples include traditional Asian medicines, ceremonial dagger handles, and decorative carvings. Indian rhinoceroses were killed during the 19th century as humans converted their natural habitat to use for agriculture. The poaching of Indian rhinoceroses for their horns is still ongoing.
Eight national parks have been created to help conserve and increase population sizes of Indian rhinoceroses. It is estimated that around 2,600 individuals are found in these protected areas as of 2015. This figure is a drastic improvement from the estimate of 150 individuals alive at the beginning of the 19th century. The national parks have provided a safe home for Indian rhinoceroses by implementing strict rules to decrease poaching and reduce the amount of human contact with Indian rhinoceroses. Such rules include building fences to forbidding unauthorized individuals from interacting with rhinoceroses. Some national parks have also taken action to control invasive plants. This ensures that the rhinoceroses have an abundant supply of the native plants in their diet. Indian rhinoceroses are also part of captive breeding programs, where authorized facilities such as zoological parks breed and release individuals to increase population sizes and genetic diversity.
Two new programs, the Indian Rhino Vision 2020 and a Nepal Rhino Action Plan have been developed. These programs facilitate rhinoceros transportation to underpopulated regions, such as Manas National Park. These programs are also involved with a number of plans to bolster conservation. Conservation methods include increasing safety from poachers, limiting contact with humans, assessing habitat needs and status, and educating locals on the conservation issues of Indian rhinoceroses.
The major problem with current conservation efforts is that the majority of living Indian rhinoceroses are found within a patch of suitable habitat only 500 km² large. This puts the species at risk for a catastrophic population decline if this area is subjected to a disease breakout, large flood, or a breakdown in the laws set forth by national park officials. There are plans to reintroduce Indian rhinoceroses in northwestern India and parts of Pakistan to ensure there are other healthy populations. (Adhikari, 2002; Hutchins and Kreger, 2006; Konwar, et al., 2009; Talukdar, et al., 2014)
Diego Arias (author), Radford University, Karen Powers (editor), Radford University, April Tingle (editor), Radford University, Emily Clark (editor), Radford University, Cari Mcgregor (editor), Radford University, Jacob Vaught (editor), Radford University, Galen Burrell (editor), Special Projects.
uses sound to communicate
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.
uses smells or other chemicals to communicate
active at dawn and dusk
a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
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.
parental care is carried out by females
union of egg and spermatozoan
an animal that mainly eats leaves.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
an animal that mainly eats fruit
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
marshes are wetland areas often dominated by grasses and reeds.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
found in the oriental region of the world. In other words, India and southeast Asia.
chemicals released into air or water that are detected by and responded to by other animals of the same species
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
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.
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.
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.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
breeding takes place throughout the year
young are relatively well-developed when born
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