Asian elephant

Asian elephant
Temporal range:
Pliocene – Holocene,[1] 2.5–0 Ma
↓
A male Asian elephant in Bandipur National Park, India
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Class: Mammalia
Order: Proboscidea
Family: Elephantidae
Genus: Elephas
Species: E. maximus[3]
Binomial name
Elephas maximus[3]
Linnaeus, 1758
Subspecies

E. m. maximus
E. m. indicus
E. m. sumatranus
E. m. borneensis

Asian elephant range

The Asian or Asiatic elephant (Elephas maximus) is the only living species of the genus Elephas and is distributed in Southeast Asia from India and Nepal in the west to Borneo in the east. Three subspecies are recognised—E. m. maximus from Sri Lanka, the E. m. indicus from mainland Asia, and E. m. sumatranus from the island of Sumatra.[3] Asian elephants are the largest living land animals in Asia.[4]

Since 1986, the Asian elephant has been listed as endangered by the International Union for Conservation of Nature (IUCN) as the population has declined by at least 50 percent over the last three generations, estimated to be 60–75 years. Asian elephants are primarily threatened by loss of habitat, habitat degradation, fragmentation and poaching.[2] In 2003, the wild population was estimated at between 41,410 and 52,345 individuals. Female captive elephants have lived beyond 60 years when kept in semi-natural surroundings, such as forest camps. In zoos, elephants die at a much younger age and are declining due to a low birth and high death rate.[5]

The genus Elephas originated in Sub-Saharan Africa during the Pliocene, and spread throughout Africa before emigrating into southern Asia.[1] The earliest indications of captive use of Asian elephants are engravings on seals of the Indus Valley civilization dated to the third millennium BC.[6]

Taxonomy

Sri Lankan elephants

Carl Linnaeus first described the genus Elephas and an elephant from Ceylon under the binomial Elephas maximus in 1758.[7] In 1798, Georges Cuvier first described the Indian elephant under the binomial Elephas indicus.[8] In 1847, Coenraad Jacob Temminck first described the Sumatran elephant under the binomial Elephas sumatranus.[9] Frederick Nutter Chasen classified all three as subspecies of the Asian elephant in 1940.[10]

Three subspecies are currently recognised: the Sri Lankan elephant, the Indian elephant, and the Sumatran elephant.[2][4] In 1950, Paules Edward Pieris Deraniyagala described the Borneo elephant under the trinomial Elephas maximus borneensis, taking as his type an illustration in National Geographic, but not a living elephant in accordance with the rules of the International Code of Zoological Nomenclature.[11] E. m. borneensis lives in northern Borneo and is smaller than all the other subspecies, but with larger ears, a longer tail, and straight tusks. Results of genetic analysis indicate that its ancestors separated from the mainland population about 300,000 years ago.[12]

The population in Vietnam and Laos was tested to determine if it is a subspecies as well. This research is considered vital, as less than 1,300 wild Asian elephants remain in Laos.[13] In addition, two extinct subspecies are considered to have existed:

Characteristics

Illustration of an elephant skeleton[14]

In general, the Asian elephant is smaller than the African elephant and has the highest body point on the head. The back is convex or level. The ears are small with dorsal borders folded laterally. It has up to 20 pairs of ribs and 34 caudal vertebrae. The feet have more nail-like structures than those of African elephants—five on each forefoot, and four on each hind foot.[4]

Size

Average shoulder height of females is 2.4 m (7.9 ft), and average weight is 2.7 t (3.0 short tons), while average shoulder height of males is 2.75 m (9.0 ft), and average weight is 4 t (4.4 short tons).[15][16][17] Length of body and head including trunk is 5.5–6.5 m (18–21 ft) with the tail being 1.2–1.5 m (3.9–4.9 ft) long.[4] The largest bull elephant ever recorded was shot by the Maharajah of Susang in the Garo Hills of Assam, India in 1924, it weighed 7 tonnes (7.7 short tons), stood 3.43 m (11.3 ft) tall at the shoulder and was 8.06 m (26.4 ft) long from head to tail.[17][18][19] There are reports of larger individuals as tall as 3.7 m (12 ft).[14]

Trunk

Asian elephant drinking water

The distinctive trunk is an elongation of the nose and upper lip combined; the nostrils are at its tip, which has a one finger-like process. The trunk contains as many as 60,000 muscles, which consist of longitudinal and radiating sets. The longitudinals are mostly superficial and subdivided into anterior, lateral, and posterior. The deeper muscles are best seen as numerous distinct fasciculi in a cross-section of the trunk. The trunk is a multipurpose prehensile organ and highly sensitive, innervated by the maxillary division of the trigeminal nerve and by the facial nerve. The acute sense of smell uses both the trunk and Jacobson's organ. Elephants use their trunks for breathing, watering, feeding, touching, dusting, sound production and communication, washing, pinching, grasping, defense and offense.[4]

The "proboscis" or trunk consists wholly of muscular and membranous tissue, and is a tapering muscular structure of nearly circular cross-section extending proximally from attachment at the anterior nasal orifice, and ending distally in a tip or finger. The length may vary from 1.5 to 2 m (59 to 79 in) or longer depending on the species and age. Four basic muscle masses—the radial, the longitudinal and two oblique layers—and the size and attachments points of the tendon masses allow the shortening, extension, bending, and twisting movements accounting for the ability to hold, and manipulate loads of up to 300 kg (660 lb). Muscular and tendinous ability combined with nervous control allows extraordinary strength and agility movements of the trunk, such as sucking and spraying of water or dust and directed air flow blowing.[20]

The trunk can hold about four litres of water. Elephants will playfully wrestle with each other using their trunks, but generally use their trunks only for gesturing when fighting.[21]

Tusks

Tusker debarking a tree

Tusks serve to dig for water, salt, and rocks, to debark and uproot trees, as levers for maneuvering fallen trees and branches, for work, for display, for marking trees, as weapon for offense and defense, as trunk-rests, and as protection for the trunk. Elephants are known to be right or left tusked.[4]

Female Asian elephants usually lack tusks; if tusks—in that case called "tushes"—are present, they are barely visible, and only seen when the mouth is open. The enamel plates of the molars are greater in number and closer together in Asian elephants. Some males may also lack tusks; these individuals are called "filsy makhnas", and are especially common among the Sri Lankan elephant population. Furthermore, the forehead has two hemispherical bulges, unlike the flat front of the African elephant. Unlike African elephants which rarely use their forefeet for anything other than digging or scraping soil, Asian elephants are more agile at using their feet in conjunction with the trunk for manipulating objects. They can sometimes be known for their violent behaviour.[22]

A record tusk described by George P. Sanderson measured 5 ft (1.5 m) along the curve, with a girth of 16 in (41 cm) at the point of emergence from the jaw, the weight being 104 1⁄2 lb (47.4 kg). This was from an elephant killed by Sir Brooke and measured 8 ft (2.4 m) in length, and nearly 17 in (43 cm) in circumference, and weighed 90 lb (41 kg). The tusk's weight was, however, exceeded by the weight of a shorter tusk of about 6 ft (1.8 m) in length which weighed 100 lb (45 kg).[14]

Skin

Depigmented skin on the forehead and ears of an Asian elephant

Skin colour is usually gray, and may be masked by soil because of dusting and wallowing. Their wrinkled skin is movable and contains many nerve centers. It is smoother than that of African elephants, and may be depigmented on the trunk, ears, or neck. The epidermis and dermis of the body average 18 mm (0.71 in) thick; skin on the dorsum is 30 mm (1.2 in) thick providing protection against bites, bumps, and adverse weather. Its folds increase surface area for heat dissipation. They can tolerate cold better than excessive heat. Skin temperature varies from 24 to 32.9 °C (75.2 to 91.2 °F). Body temperature averages 35.9 °C (96.6 °F).[4]

Intelligence

Asian elephants are highly intelligent and self-aware.[23] They have a very large and highly convoluted neocortex, a trait also shared by humans, apes and certain dolphin species. Elephants have a greater volume of cerebral cortex available for cognitive processing than all other existing land animals, and extensive studies place elephants in the category of great apes in terms of cognitive abilities for tool use and tool making.[24] They exhibit a wide variety of behaviours, including those associated with grief, learning, allomothering, mimicry, play, altruism, use of tools, compassion, cooperation, self-awareness, memory, and language. Elephants are reported to go to safer ground during natural disasters like tsunamis and earthquakes, although there have been no scientific records of this since it is hard to recreate or predict natural disasters.

Distribution and habitat

A herd of elephants in the grasslands of Jim Corbett National Park
Asiatic Elephant grazing along the banks of Kabini, Nagarhole National Park, Karnataka, India

Asian elephants inhabit grasslands, tropical evergreen forests, semi-evergreen forests, moist deciduous forests, dry deciduous forests and dry thorn forests, in addition to cultivated and secondary forests and scrublands. Over this range of habitat types elephants occur from sea level to over 3,000 m (9,800 ft). In the eastern Himalaya in northeast India, they regularly move up above 3,000 m (9,800 ft) in summer at a few sites.[25]

In China, Asian elephants survive only in the prefectures of Xishuangbanna, Simao, and Lincang of southern Yunnan.

In Bangladesh, some isolated populations survive in the south-east Chittagong Hills.[6] A herd of 20-25 wild elephants was reported as being present in the Garo Hills of Mymensingh in the late-1990s, being detached from a big herd in the Peack hills of India and prevented from returning by fences put up in the meantime by the Indian border security force. The herd was estimated at about 60 individuals in 2014.[26]

Three subspecies are recognised:[2][4]

The Borneo elephant occurs in Borneo's northern and northeastern parts.[27] In 2003, mitochondrial DNA analysis and microsatellite data indicated that the Borneo elephant population is derived from stock that originated in the region of the Sunda Islands. The genetic divergence of Borneo elephants warrants their recognition as a separate Evolutionarily Significant Unit.[28]

Ecology and behaviour

A 5-month-old calf and its 17-month-old cousin in a sanctuary in Laos

Elephants are crepuscular.[4] They are classified as megaherbivores and consume up to 150 kg (330 lb) of plant matter per day.[29] They are generalist feeders, and both grazers and browsers, and were recorded to feed on 112 different plant species, most commonly of the order Malvales, and the legume, palm, sedge and true grass families.[30] They browse more in the dry season with bark constituting a major part of their diet in the cool part of that season.[31] They drink at least once a day and are never far from a permanent source of fresh water.[4] They need 80–200 litres of water a day and use even more for bathing. At times, they scrape the soil for clay or minerals.

Adult females and calves may move about together as groups, but adult males disperse from their mothers upon reaching adolescence. Bull elephants may be solitary or form temporary 'bachelor groups'.[32]

Cow-calf unit sizes generally tend to be small, typically consisting of three adult females which are most likely related,[33] and their offspring; however, larger groups containing as many as 15 adult females may occur.[34] There can also be seasonal aggregations containing 100 individuals at a time, including calves and subadults. Until recently, Asian elephants, like African elephants, were thought to typically follow the leadership of older adult females, or matriarchs, but females can form extensive and very fluid social networks, with individual variation in the degree of gregariousness.[35] Social ties generally tend to be weaker than in African elephants.[34]

Elephants are able to distinguish low amplitude sounds.[36] They use infrasound to communicate; this was first noted by the Indian naturalist Krishnan and later studied by Payne.[37]

Tiger predation on Asian elephants is rare but is not restricted only to small calves.[38][39][40]

Reproduction

Indian elephants in the Coimbatore Forests, Tamil Nadu

Bulls will fight one another to get access to oestrous females. Strong fights over access to females are extremely rare. Bulls reach sexual maturity around the age of 12–15. Between the age of 10 and 20 years, bulls undergo an annual phenomenon known as "musth". This is a period where the testosterone level is up to 100 times greater than non-musth periods, and they become aggressive. Secretions containing pheromones occur during this period, from the paired temporal glands located on the head between the lateral edge of the eye and the base of the ear.[41]

The gestation period is 18–22 months, and the female gives birth to one calf, only occasionally twins. The calf is fully developed by the 19th month, but stays in the womb to grow so that it can reach its mother to feed. At birth, the calf weighs about 100 kg (220 lb), and is suckled for up to three years. Once a female gives birth, she usually does not breed again until the first calf is weaned, resulting in a four to five year birth interval. Females stay on with the herd, but mature males are chased away.[42]

Asiatic elephants reach adulthood at 17 years of age in both sexes.[43] Elephants' life expectancy has been exaggerated in the past. They live on average for 60 years in the wild and 80 in captivity.[4]

Females produce sex pheromones. A principal component thereof, (Z)-7-dodecen-1-yl acetate, has also been found to be a sex pheromone in numerous species of insects.[44][45]

Interaction with humans

Elephants are used for safari tourism throughout Asia
Sri Lankan elephants at Esala Perahera
At this elephant training camp, captive elephants are taught to handle logs.

At most seasons of the year, Asian elephants are timid and much more ready to flee from a foe than to attack. However, solitary rogues are frequently an exception to this rule, and sometimes make unprovoked attacks on passers-by. Rogue elephants sometimes take up a position near a road, making it impassable to travelers. Females with calves are at all times dangerous to approach. When an Asian elephant makes a charge, it tightly curls up its trunk and attacks by trampling its victim with feet or knees, or, if a male, by pinning it to the ground with its tusks. During musth, bulls are highly dangerous, not only to human beings, but also to other animals. At the first indications, trained elephants are secured tightly to prevent any mishaps. There is also one case of a rogue elephant having actually consumed a human, an attack merited to be extremely unnatural. The elephant, a rogue female, had previously lost her calf to an accident involving farmers. This grievous loss led the elephant to target humans first as a threat, and then as a food source as her mental state deteriorated until she was finally killed and later dissected, revealing through DNA analysis that she had indeed consumed human flesh. The incident was revealed to the general public in several articles and in the Animal Planet documentary "World's Deadliest Towns: Man-Eating Elephant".[46]

Domestication

The first historical record of the domestication of Asian elephants was in Harappan times.[47] Ultimately, the elephant went on to become a siege engine, a mount in war, a status symbol, a beast of burden, and an elevated platform for hunting during historical times in South Asia.[48]

Elephants have been captured from the wild and tamed for use by humans. Their ability to work under instruction makes them particularly useful for carrying heavy objects. They have been used particularly for timber-carrying in jungle areas. Other than their work use, they have been used in war, in ceremonies, and for carriage. It is reported that war elephants are still in use by the Kachin Independence Army (KIA) to defend Kachin State in northern Myanmar against domination by Myanmar's military. The KIA use about four dozen elephants to carry supplies.[49] They have been used for their ability to travel over difficult terrain by hunters, for whom they served as mobile hunting platforms. The same purpose is met in safaris in modern times.

Threats

The pre-eminent threats to Asian elephants today are loss, degradation and fragmentation of habitat, leading in turn to increasing conflicts between humans and elephants. They are poached for ivory and a variety of other products including meat and leather.[2]

Human–elephant conflict

Prime elephant habitat cleared for jhum—a type of shifting cultivation practiced in Arunachal Pradesh
Elephants on the road in Khao Yai National Park, Thailand

One of the major instigators of human–wildlife conflict is competition for space. Destruction of forests through logging, encroachment, slash-and-burn, shifting cultivation, and monoculture tree plantations are major threats to the survival of elephants. Human–elephant conflicts occur when elephants raid crops of shifting cultivators in fields, which are scattered over a large area interspersed with forests. Depredation in human settlements is another major area of human–elephant conflict occurring in small forest pockets, encroachments into elephant habitat, and on elephant migration routes.[50] Studies in Sri Lanka indicate that traditional slash-and-burn agriculture creates optimal habitat for elephants by creating a mosaic of successional-stage vegetation. Populations inhabiting small habitat fragments are much more liable to come into conflict with humans.[51]

Human-elephant conflict is categorized into:[52]

Development such as border fencing along the India-Bangladesh border has become a major impediment to the free movement of elephants.[53] In Assam, more than 1,150 humans and 370 elephants died as a result of human-elephant conflict between 1980 and 2003.[50] In India alone, over 400 people are killed by elephants every year, and 0.8 to 1 million hectares are damaged, affecting at least 500,000 families across the country.[54] Moreover, elephants are known to destroy crops worth up to US$2–3 million annually.[55] This has major impacts on the welfare and livelihoods of local communities, as well as the future conservation of this species.[52]

Poaching

18th century ivory powder flask

The demand for ivory as a result of rapid economic development during the 1970s and 1980s, particularly in East Asia, led to rampant poaching and the serious decline of elephants in many Asian and African range countries. In Thailand, the illegal trade in live elephants and ivory still flourishes. Although the quantity of worked ivory seen openly for sale has decreased substantially since 2001, Thailand still has one of the largest and most active ivory industries seen anywhere in the world. Tusks from Thai poached elephants also enter the market; between 1992 and 1997 at least 24 male elephants were killed for their tusks.[56]

Up to the early 1990s, Vietnamese ivory craftsmen used exclusively Asian elephant ivory from Vietnam and neighbouring Lao PDR and Cambodia. Before 1990, there were few tourists and the low demand for worked ivory could be supplied by domestic elephants. Economic liberalization and an increase in tourism raised both local and visitors’ demands for worked ivory, which resulted in heavy poaching.[57]

Handling methods

Young elephants are captured and illegally imported to Thailand from Myanmar for use in the tourism industry; calves are used mainly in amusement parks and are trained to perform various stunts for tourists.[56]

The calves are often subjected to a 'breaking in' process, which may involve being tied up, confined, starved, beaten and tortured; as a result, two-thirds may perish.[58] Handlers use a technique known as the training crush, in which "handlers use sleep-deprivation, hunger, and thirst to "break" the elephants' spirit and make them submissive to their owners"; moreover, handlers drive nails into the elephants' ears and feet.[59]

Conservation

Elephas maximus is listed on CITES Appendix I.[2]

Asian elephants are quintessential flagship species, deployed to catalyze a range of conservation goals, including:

In captivity

Rhythmic swaying behaviour is not reported in free ranging wild elephants, and may be symptomatic of psychological disorders.

About half of the global zoo elephant population is kept in European zoos, where they have about half the median life span of conspecifics in protected populations in range countries. This discrepancy is clearest in Asian elephants: infant mortality is twice that seen in Burmese timber camps, and adult survivorship in zoos has not improved significantly in recent years. One risk factor for Asian zoo elephants is being moved between institutions, with early removal from the mother tending to have additional adverse effects. Another risk factor is being born into a zoo rather than being imported from the wild, with poor adult survivorship in zoo-born Asians apparently being conferred prenatally or in early infancy. Likely causes for compromised survivorship is stress and/or obesity.[62]

Demographic analysis of captive Asian elephants in North America indicates that the population is not self-sustaining. First year mortality is nearly 30 per cent, and fecundity is extremely low throughout the prime reproductive years.[63] Data from North American and European regional studbooks from 1962 to 2006 were analysed for deviation of the birth and juvenile death sex ratio. Of 349 captive calves born, 142 died prematurely. They died within one month of birth, major causes being stillbirth and infanticide by either the calf's mother or by one of the exhibition mates. The sex ratio of stillbirths in Europe was found to have a tendency for excess of males.[64]

In culture

A folio from the Hastividyarnava manuscript

The elephant plays an important part in the culture of the subcontinent and beyond, being featured prominently in the Panchatantra fables and the Buddhist Jataka tales. They play a major role in Hinduism: the god Ganesha's head is that of an elephant, and the "blessings" of a temple elephant are highly valued. Elephants are frequently used in processions where the animals are adorned with festive outfits.

The elephant is depicted in several Indian manuscripts and treatises. Notable amongst these is the Matanga Lila (elephant sport) of Nilakantha.[65] The manuscript Hastividyarnava is from Assam in northeast India.

In the Burmese, Thai and Sinhalese animal and planetary zodiac, the elephant, both tusked and tuskless, are the fourth and fifth animal zodiacs of the Burmese, the fourth animal zodiac of the Thai, and the second animal zodiac of the Sinhalese people of Sri Lanka.[66] Similarly, the elephant is the twelfth animal zodiac in the Dai animal zodiac of the Dai people in southern China.[67]

See also

References

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