The rhinoceros has one horn (both male and female),
and its skin has loose folds and rivet-like knobs which make it appear armored.
A female rhino weighs about 1600 kg (3500 lb), while a male weighs about
2200 kg (4800 lb). The average height of a female is 1.6 m (5.2'); males
average 1.8 m (5.9') tall. The rhino is found throughout its present
range inalluvialplain habitats: riverine grasslands with
grass up to 8 m (26') tall and marshy areas bordered by riverine woodlands,
driersal forest, or tropical almond
forest. It now often uses cultivated areas, pastures, and modified woodlands.
The rhino's diet consists mainly of grass but also includes fruit,
leaves, branches of trees and shrubs, and cultivated crops.
The rhino is active mostly at night, in early morning
and in the late afternoon. The middle of the day is usually spent resting,
either in the shade or in wallows. Apart from cow-calf pairs, rhinos
rarely form groups. Adult males are usually solitary, but they sometimes occur
in temporary associations at wallows and grazing grounds where they often feed
or rest together but move independently of each other. The rhino is not
territorial. The home ranges of dominant bulls overlap with one another, with
ranges of weaker males that do not attempt to mate, and with ranges of females.
In historic times, the rhino occurred in the
sub-Himalayan region all along the Indus, Gangesand BrahmaputraRiver
basins. It disappeared over much of its range
between 1600 - 1900. By the beginning of the 20th century, it was close to
extinction. At that point there was a change in human treatment of the
rhino: hunting was halted and general legal protection was established. For
most of the 20th century, populations of the Indian rhino have been
concentrated in southern Nepaland northeastern India.
By the late 20th century, the Indian rhino was confined to a few isolated
patches in the Nepalterai, West Bengal (India),
and the BrahmaputraValleyin Assam (India).
Fortunately, the total population increased considerably during the second half
of the 20th century (See Population Estimates below.).
The main reason for the decline of the rhino from its
historical levels was the loss of alluvial plain grasslands to agricultural
development, which destroyed the rhino's prime habitat, led to conflicts with
human interests, and made the rhino more accessible to hunters. In the early
20th century, hunting was prohibited. Currently, with most rhinos occurring
only in sanctuaries, poaching (mainly for use of its horn in Oriental medicine)
is still a major problem, as well as competition for grazing with domestic
stock and trespass in sanctuaries by villagers for firewood and fodder.
Tidbits
*** As early as 1952, the public of Assam,India (where
many of the remaining rhinos occurred) was becoming sensitive to the
value of the region's wildlife and the importance of its preservation (Gee
1952). This was especially significant for the continued survival of the Indian
rhino, because experience showed that, in some areas, the rhino preferred the
vicinity of villages and cultivation to undisturbed forests and grassland. This
was apparently due to its preference for man-grown crops. The rhinos did not
object to sharing their grazing with domestic stock. In Nepalthe common grazing grounds were apparently grazed by domestic stock by day and
rhinos by night (Gee 1959).
*** Indiaand Nepalincreased security against poaching beginning in 1994, and poaching has
decreased significantly. About 40 rhino poachers were in jail in Nepalin 1995, and the sentences are usually upheld. Most poachers in Indiaand Nepal are
caught through informers, who are paid for information on a regular basis by
the International Trust for Nature Conservation. The funds are raised from
individual donors and through a collection box at Tiger Tops Jungle Lodge in Chitwan
National Park, Nepal(Martin & Vigne 1996).
***As an indication of the incentive for poaching of rhino horns,
consider that the wholesale value of Asian rhino horn increased from US $35/kg
($16/lb) in 1972 to $18,000/kg ($8000/lb) in 1991. The retail price, after the
horn has been shaved or powdered for sale, has at times and in some East Asian
markets exceeded $50,000/kg ($23,000/lb). By contrast, in November 1996 pure
gold was worth about $12,000/kg ($5500/lb) (about one quarter of the maximum
value of rhino horn). (Nowak 1999)
*** In KazirangaNational
Park in Assam,India, tiger
predation is the second biggest threat to the Indian rhino after poaching.
(Oryx 1998b)
*** The rhino's horn is composed of agglutinated fibers
sitting on the skull. It is not firmly connected to the bones of the skull.
Status and Trends
IUCN Status:
[The IUCN (International Union for the Conservation of
Nature; also called the World Conservation Union) is the world’s largest
conservation organization. Its members include countries, government agencies,
and non-governmental organizations.The
IUCN determines the worldwide status of threatened animals and publishes the
status in its Red List.]
Countries Where the
Indian Rhinoceros Is Currently Found:
2004: Occurs in Bhutan,India and Nepal.
(IUCN 2004)
Population Estimates:
[Note: Figures
given are for wild populations only.]
* WORLD
o 1952: 350
(Gee 1952)
o 1958: 700
(Gee 1959)
o 1963: 600
(Oryx 1964b)
o 1964: 625
(Gee 1964)
o 1966: 740
(Oryx 1966c)
o 1968: 680
(Oryx 1968a)
o 1971: 630
(Fitter 1974)
o 1983: 1000
(Nowak & Paradiso 1983)
o 1984: 1500
(Macdonald 1984)
o 1986: 1711
(Martin et al. 1987)
o 1987: 1700
(Sale & Singh 1987)
o 1990: 1700
(Foose 1990)
o 1994: 1900
(Anon. 1994a)
o 1995: 2135
(Martin & Vigne 1996)
o 1997:
About 2095 (WCMC/WWF 1997)
o 1998:
Approximately 2100 (AZA 1998a)
o 2000:
About 2500 (Khan et al. 2000)
o 2002:
About 2500 (Talukdar 2002)
o 2005: 2400
(Intl. Rhino Found. 2005)
* India
o 1910: Less
than 50 (Martin et al. 1987)
o 1950: 263
(Shebbeare 1953)
o 1952: 300
(Gee 1952)
o 1953: 370
(Shebbeare 1953)
o 1958: 400
(Gee 1958)
o 1961: 440
(IUCN 1967)
o 1964: 440
(Gee 1964)
o 1966: 575
(IUCN 1967)
o 1981: 1600
(Oryx 1981b)
o 1986: 1334 (Martin et al. 1987)
o 1989: 1557
(Vigne & Martin 1991)
o 1995: 1600
(Martin & Vigne 1996)
* Nepal
o 1952: 50
(Gee 1952)
o 1959: 300
(Gee 1959)
o 1960: 200
- 225 (Gee 1963)
o 1961: 160
(Gee 1963)
o 1964: 185
(Gee 1964)
o 1966: 165
(IUCN 1967)
o 1968: 81 -
108 (Caughley & Gunn 1996)
o 1982: 375
(Martin 1985)
o 1986: 375
(Martin et al. 1987)
o 1989: 400
(Vigne & Martin 1991)
o 1995: More
than 500 (Martin & Vigne 1996)
o 2000: 612
(Martin 2001)
o 2005: More
than 600 (Oryx 2001b)
* Pakistan
o 1986: 2
(Martin et al. 1987)
o 1989: 2
(Vigne & Martin 1991)
History of
Distribution:
The rhino occurred in the sub-Himalayan region in
historic times, all along the Indus, Gangesand BrahmaputraRiver
basins. The western limit of its range was the
foothills of the Hindu Kush west of Peshawar(Pakistan). The
eastern limit of its historic range is uncertain. Some authors believe that it
occurred in Cambodia,Laos, Thailandand Vietnam.
Others believe that it never occurred east of the India-Myanmar border, and
that reports from east of that border were mistaken, caused by confusing the
Indian rhino with the Javan rhino (Rhinoceros sondaicus) or the Sumatran rhino
(Dicerorhinus sumatrensis).
The rhino remained common in northwest Indiaand Pakistanuntil about 1600. It disappeared from those regions shortly thereafter and
declined sharply in the remainder of its range over the next 300 years. The
main reason for this was the loss of alluvial plain grasslands to agricultural
development, which destroyed the rhino's prime habitat, led to conflicts with human
interests, and made the rhino more accessible to hunters. Sport hunting of the
species by both Europeans and Asians became very popular in the late 19th and
early 20th centuries. Even more rhinos were systematically slaughtered
during this period for a government bounty established to protect tea
plantations from damage due to rhinos. By the first decade of the 20th century,
the rhino was close to extinction. In Indiathere were only a few scattered survivors, the main group comprised of 12
individuals along the BrahmaputraRiverin the Kaziranga area of Assam.
In Nepal there
were perhaps another 50. At that point there was a change in human treatment of
the Indian rhino: the bounty and sport hunting were halted, general legal
protection was established, and Kaziranga was made a reserve. (Nowak 1999)
For most of the 20th century, populations of the rhino have been concentrated in southern Nepaland northeastern India.
By the late 20th century, the rhino was confined to a few isolated
patches in the Nepalterai, West Bengal (India),
and the BrahmaputraValleyin Assam (India)
(Javed 1993). Fortunately, the total population increased considerably during
the second half of the 20th century (See Population Estimates above.).
Distribution Map (5 Kb GIF) (Huffman 2004)
Distribution Map (30 Kb JPEG) (Intl. Rhino Found. 2004)
Threats and Reasons for Decline:
By the early 1900's, the rhino was already thought to
be a "vanishing race." Hunting was important to the decline, but
man's modification of the rhino's habitat for cultivation and grazing was
instrumental in reducing the rhino population to the point where hunting became
critical (IUCN 1967). Currently, with most rhinos occurring only in
sanctuaries, poaching (mainly for use of its horn in Oriental medicine) is
still a major problem, as well as competition for grazing with domestic stock
and trespass in sanctuaries by villagers for firewood and fodder.
Data on Biology and Ecology
Size and Weight:
A female rhino weighs about 1600 kg (3500 lb); a male weighs about: 2200 kg (4800 lb).
The average height of a female is 1.6 m (5.2'); for a male, it is 1.8 m (5.9')
(Laurie et al. 1983).
Habitat:
In the past, the
rhino was recorded from a number of habitats, including marshy lowland
and reed beds; tall grass or bush with patches of savanna and occasional
streams and swamps; thick tree and scrub riverine forest; and dry, mixed
forest. It is found throughout its present range in alluvial plain habitats:
riverine grasslands with grass up to 8 m (26') tall and marshy areas bordered
by riverine woodlands, drier sal forest, or tropical almond forest.Furthermore, its range now has been so
restricted by human activity that it often uses cultivated areas, pastures, and
modified woodlands. (Laurie et al. 1983, Nowak 1999)
The rhino
is one of the species that live in both the Himalaya and
Indo-Burma Biodiversity Hotspots (Cons. Intl.) and the Terai-Duar Savannas
& Grasslands Global 200 Ecoregion. (Olson & Dinerstein 1998, Olson
& Dinerstein 1999)
Age to Maturity:
A female rhino is fully grown at 4 years in captivity but not until about 6.5 years in
the wild.A male rhino is fully
grown at 8 years of age in captivity but at about 10 years of age in the wild.
In Chitwan (Nepal),
female rhinos have their first calves at 6 - 8 years of age. (Laurie et
al. 1983)The average age of females at
sexual maturity is 7.0 - 7.5 years (Nowak 1999).
Mating takes place
throughout the year (Laurie et al. 1983).
Birth Rate:
One rhino
calf is usually born at a time. The time between births can be as short as 22
months but usually is 2 - 4 years (Macdonald 1984).In Nepalthe birth interval is commonly 3 - 5 years (Nowak 1999).
In one study,
three estimates of annual female reproductive rate were derived (using various
data sources): 0.357 calves born/adult female/year (assuming a 2.8 year
intercalving interval), 0.286 calves/adult female/year (assuming a 3.5 year
intercalving interval), and, 0.25 calves born/adult female/year (assuming a 4
year intercalving interval). (Rothley et al. 2004)
Early Development:
Calves are suckled
frequently up to the age of 1 year and only rarely after the age of 18 months.
Up to the age of 6 months, calves are left alone for periods as long as 90
minutes while their mothers feed up to 800 m (2600') away. (Laurie et al. 1983)
Dispersal:
Male calves leave
their mothers at an average age of 39 months compared with 34 months for female
calves (Laurie et al. 1983). A calf is driven away by its mother at least one
week before the birth of the next calf. (Nowak 1999)
Maximum Age:
The record
longevity in captivity is 47 years (Laurie et al. 1983).
Diet:
The rhino's
diet consists mainly of grass. It also includes fruit, leaves, branches of
trees and shrubs, and cultivated crops.Salt licks are visited regularly. (Nowak 1999) The Indian rhino uses its
prehensile upper lip to browse tall grass and shrubs. It can fold the tip of
its lip away when feeding on short grass. (Macdonald 1984) The rhino
drinks daily from streams, rivers, lakes, puddles, or wallows. Rhinos often
drink very dirty water heavily contaminated with rhino urine. (Laurie et al.
1983)
In Nepal,
rhinos were observed to feed on 183 species of plants, with grasses
making up between 70 - 89% of the diet depending on the season. Other foods
included fruits, leaves and branches of shrubs and trees, sedges and ferns,
submerged and floating aquatic plants, and cultivated crops. (Laurie et al.
1983)
Behavior:
Females choose
secluded areas to give birth in (Laurie et al. 1983).
Senses: For all
species of rhino, smell is the strongest sense, although their mobile, tubular
ears provide good hearing. The eyes, however, are small, and rhinos have poor
vision. (Burnie & Wilson 2001)
Activity Patterns:
The rhino is active mainly at night, in early morning and in the late
afternoon. The middle of the day is mainly spent resting, either in the shade
or in wallows. During the monsoon this pattern changes slightly - there are
cool, wet days when rhinos feed at mid-day. Crop-raiding takes place
exclusively at night - much later during moonlit nights than during moonless or
cloudy nights. Less time is spent feeding during the monsoon (36%) than during
the spring (65%) and winter (57%). There is often a rest period during the
night, between midnight and 0300 h (3:00 am). (Laurie et al. 1983)
Wallowing: The
rhino wallows in lakes, rivers, and temporary pools. In Chitwan,
Nepal, it wallowed most
frequently between June and October (51% of observations) and least frequently
between December and March (4% of observations). Heat regulation is probably a
major function of wallowing, but escape from flies, especially in tall
grasslands during the monsoon, may also be important. (Laurie et al. 1983)
Movement: The
rhino is the most aquatic rhino, wading and swimming with ease (Burnie
& Wilson 2001).
Social Organization:
Apart from
cow-calf pairs, rhinos rarely form groups. Adult males are usually
solitary, but they sometimes occur in temporary associations of up to nine
rhinos of various sex and age classes. These groups form at wallows and grazing
grounds where the rhinos often feed or rest together but move independently of
each other. In one study in Chitwan, Nepal,
only 15% of the sightings of rhinos were groups other than cow-calf
pairs. Only seven groups consisted of more than three individuals and the most
common type of group was comprised of two or three subadults, usually subadult
males, which had recently left their mothers. The largest group recorded in
Chitwan was of six subadults. (Laurie et al. 1983)
Among rhinos, there is some degree of range exclusivity but no true territoriality.
The home ranges of dominant bulls overlap with one another, with ranges of
weaker males that do not attempt to mate, and with ranges of females. When two
dominant rhino males meet, they may fight using their tusk-like lower
incisors. These conflicts can end in the death of one of the combatants.
(Laurie et al. 1983, Nowak 1999, Burnie & Wilson 2001)
Age and Gender
Distribution:
The age
distribution of Indian rhinos in Chitwan, Nepal was reported in two studies as:
1) 27% calves, 21% subadults, 32% adult females, and 20% adult males (Laurie et
al. 1983); and 2) 14% calves, 14% subadults, and 65% adults (1988 data)
(Rothley et al. 2004).[Note: In both
cases, the life stages are defined as: calves: ages less than 4 years,
subadults: ages 4 - 6 years, and adults: ages 7 years and older.]
Mortality and
Survival:
Annual natural
mortality rates for the rhino have been reported as: 2.8% for calves,
2.2% for subadults and 2.9% for adults in Chitwan,
Nepal. These rates
include natural mortality causes such as tiger predation, separation of calves
from their mothers, floods, quicksand, and fights with conspecifics, but they
do not include poaching. (Rothley et al. 2004) [Note: The life stages are
defined as: calves: ages less than 4 years, subadults: ages 4 - 6 years, and
adults: ages 7 years and older.]
Density and Range:
Density
Various
studies have reported the following population densities of the rhino:
more than 2.0 rhinos/sq km (5.2 rhinos/sq mi) in Kaziranga, Assam in India
(Laurie et al. 1983); up to 4.85 rhinos/sq km (12.6 rhinos/sq mi) in favored
high-diversity habitat in Chitwan, Nepal (Nowak 1999); and 1.7 - 3.2 rhinos/sq
km (4.4 - 8.3 rhinos/sq mi) in grasslands and a maximum of 13.3 rhinos/sq km
(34.6 rhinos/sq mi) in riverine forest in Chitwan, Nepal (Nowak 1999).
Range
Female rhinos have home ranges covering 9 - 15 sq km (3.5 - 5.8 sq mi). Ranges of
breeding males in Chitwan, Nepalvaried from at least 2 - more than 8 sq km (0.8 - 3.1 sq mi). The range can be
temporarily enlarged when food and water supplies are low.Conversely, ranges are smallest in the
regions of greatest vegetational diversity, (Laurie et al. 1983, Macdonald
1984).
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