| Asian elephant[1] Temporal range: Late Pliocene – recent[2] |
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| Bong Su, a male Asian elephant in Melbourne Zoo | |
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Proboscidea |
| Family: | Elephantidae |
| Genus: | Elephas |
| Species: | E. maximus |
| Binomial name | |
| Elephas maximus Linnaeus, 1758 |
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| Asian Elephant range (brown — native, black — origin uncertain) |
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The Asian or Asiatic elephant (Elephas maximus) is the only living species of the genus Elephas and distributed in Southeast Asia from India in the west to Borneo in the east. Three subspecies are recognized — Elephas maximus maximus from Sri Lanka, the Indian elephant or E. m. indicus from mainland Asia, and E. m. sumatranus from the island of Sumatra.[1] Asian elephants are the largest living land animals in Asia.[4]
Since 1986, Elephas maximus has been listed as endangered by IUCN as the population has declined by at least 50% over the last three generations, estimated to be 60–75 years. The species is pre-eminently threatened by habitat loss, degradation and fragmentation.[3] In 2003, the wild population was estimated at between 41,410 and 52,345 individuals.[5]
Asian elephants are rather long-lived, with a maximum recorded life span of 86 years.
This animal is widely domesticated, and has been used in forestry in South and Southeast Asia for centuries and also for ceremonial purposes. Historical sources indicate that they were used during harvest seasons primarily for milling. Wild elephants attract tourist money to the areas where they can most readily be seen, but damage crops, and may enter villages to raid gardens.
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In general, Asian elephants are smaller than African elephants and have the highest body point on the head. Their back is convex or level. Their ears are small with dorsal borders folded laterally. They have up to 20 pairs of ribs and 34 caudal vertebrae. Their feet have more nail-like structures than the ones of African elephants — five on each forefoot, and four on each hind foot.[4]
Large bull elephants weigh up to 5,400 kg (12,000 lb) and are 3.2 m (10 ft) high at the shoulder. Females weigh up to 4,160 kg (9,200 lb) and reach 2.54 m (8.3 ft) at the shoulder. The skeleton constitutes about 15% of their body weight.[4]
The sizes of wild Asian elephants have been exaggerated in the past. Record elephants may have measured as high as 3.7 m (12 ft) at the shoulder. Shoulder height is estimated using the rule of thumb of twice the forefoot circumference.[6]
Richard Lydekker documents sizes observed in the 19th century:
The height of the adult male usually does not exceed nine feet [2.7 m], and that of the female eight feet [2.4 m]; but these dimensions are occasionally considerably exceeded. George P. Sanderson measured a male standing nine feet seven inches [2.9 m] at the shoulder, and measuring twenty-six feet two and one-half inches [8 m] from the tip of the trunk to the extremity of the tail; and he records others respectively reaching nine feet eight inches [2.9 m] and nine feet ten inches [3 m] at the shoulder. An elephant shot by General Kinloch stood upward of ten feet one inch [3.1 m]; and another measured by Sanderson ten feet seven and one-half inches [3.2 m]. These dimensions are, however, exceeded by a specimen killed by the late Sir Victor Brooke, which is reported to have reached a height of eleven feet [3.4 m]: and there is a rumor of a Ceylon elephant of twelve feet [3.7 m]. That such giants may occasionally exist is indicated by a skeleton in the Museum at Calcutta, which is believed to have belonged to an individual living between 1856 and 1860 in the neighborhood of the Rajamahal hills, in Bengal. As now mounted this enormous skeleton stands eleven feet three inches [3.4 m] at the shoulders, but Mr. O. S. Fraser, in a letter to the Asian newspaper, states that it is made to stand too low, and that its true height was several inches more. If this be so, there can be no doubt that, when alive, this elephant must have stood fully twelve feet.[6]
The heaviest bull elephant recorded was shot by the Maharajah of Susang in the Garo Hills of Assam, India in 1924, and was 8 tonnes (8.8 short tons), 3.35 m (11.0 ft) tall and 8.06 m (26.4 ft) long.[7]
The distinctive trunk is an elongation of 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 multi-purpose 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.[8]
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.[9]
Tusks serve to dig for water, salt, and rocks, to debark 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, as protection for the trunk. They are known to be right or left tusked.[4]
Female Asian elephants usually lacks tusks; if tusks — in that case called "tushes" — are present, they are barely visible, and only seen when they open the mouth. 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 behavior.[10]
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 1041⁄2 lb (47 kg). This was from an elephant killed by Sir V. 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).[6]
Skin color is usually gray, and may be masked by dirt because of dusting and wallowing. Their wrinkled skin is movable and contains many nerve centers. It is smoother than 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 to 91 °F). Body temperature averages 35.9 °C (96.6 °F).[4]
Asian elephants are highly intelligent and self-aware.[11] They have a very large and highly convoluted neocortex, a trait also shared by humans, apes and certain dolphin species. Asian elephants have the greatest volume of cerebral cortex available for cognitive processing of all existing land animals. Elephants have a volume of cerebral cortex available for cognitive processing that exceeds that of any primate species, and extensive studies place elephants in the category of great apes in terms of cognitive abilities for tool use and tool making. Elephants have been known to go to safer ground during natural disasters like tsunamis and earthquakes.[12]
Asian elephants inhabit grasslands, tropical evergreen forest, semi-evergreen forest, moist deciduous forest, dry deciduous forested and dry thorn forest, in addition to cultivated and secondary forests and scrublands. Over this range of habitat types elephants are seen 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.[13]
Three subspecies are recognized:[3][4]
In China, Asian elephants survive only in the prefectures of Xishuangbanna, Simao, and Lincang of southern Yunnan. In Bangladesh only isolated populations survive in the Chittagong Hills.[14]
Elephants are crepuscular.[4] They are megaherbivores and consume up to 150 kg (330 lb) of plant matter per day.[15] 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.[16] They browse more in the dry season with bark constituting a major part of their diet in the cool part of that season.[17]
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 minerals and occasionally will eat their own faeces if hungry.
Elephant herds follow well-defined seasonal migration routes. These are made around the monsoon seasons, often between the wet and dry zones, and it is the task of the eldest elephant to remember and follow the traditional migration routes. When human farms are founded along these old routes there is often considerable damage done to crops, and it is common for elephants to be killed in the ensuing conflicts.
A herd or clan is organized along matriarchal lines, and the older cow will coordinate movements. Herds of cows range from 8 to 21 animals. Adult males do not attach themselves to a herd of cows unless it contains a female in estrus. More than one adult male may accompany cows, but in general the dominant bull will mate with the cows. Younger bulls will occasionally engage in mock fighting. Strong fights over access to females are extremely rare.[18] Bull elephants form small groups known as 'bachelor herds', but bulls may also roam independently at various times.
Elephants are able to distinguish low amplitude sounds.[19] They use infrasound to communicate; this was first noted by the Indian naturalist M. Krishnan and later studied by Katharine Payne.[20]
An adult full grown healthy male Asian elephant has hardly any natural predators, but there have been rare instances of tigers preying on young or weak elephants.
Bulls will fight one another to get access to estrous females. Bulls reach sexual maturity around the age of 12–15. Between the age of 10 to 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 extremely 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.[21]
The gestation period is 18–22 months, and the female gives birth to one calf, or 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 2–3 years. Once a female gives birth, she usually does not breed again until the first calf is weaned, resulting in a 4–5-year birth interval. Females stay on with the herd, but mature males are chased away.
Elephants' life expectancy have 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.[22][23]
At most seasons of the year Asian elephants are timid and much more ready to flee from a foe than to make an 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 travellers. 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 its fellow animals. At the first indications, domestic elephants are secured tightly to prevent any mishaps. A grander animated object than a wild elephant in full charge can hardly be imagined. The cocked ears and broad forehead present an immense frontage; the head is held high, with the trunk curled between the tusks, to be uncoiled in the moment of attack; the massive fore-legs come down with the force and regularity of ponderous machinery; and the whole figure is rapidly foreshortened, and appears to double in size with each advancing stride. The trunk being curled and unable to emit any sound, the attack is made in silence, after the usual premonitory shriek, which adds to its impressiveness. The usual pictorial representations of the Indian elephant charging with upraised trunk are accordingly quite incorrect.[6]
The first historical record of domestication of Asian elephants was in Harappan times.[24] Ultimately the elephant went on to become a siege engine, a mount in war, a status symbol, a work animal, and an elevated platform for hunting during historical times in South Asia.[25]
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. 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.
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 the elephant. The forest cover in NE India is disappearing at an alarming rate. More than half of the elephants’ habitat has been lost since 1950. Crop raiding by elephants is a common occurrence throughout the region. During the paddy season, many elephants travel to the plains of Assam and remain at the edge of the forest for a few weeks. Among the shifting cultivators and the individuals living in the hilly areas, human–elephant conflicts occur when the elephants raid their crops, which are scattered over a large area of fields interspersed with forests. Depredation in human settlements is another major area of human–elephant conflict. Most of these conflicts, however, occur in small forest pockets, encroachments in elephant habitat, and on elephant migration routes. Between 1980 and 2003, more than 1,150 humans and 370 elephants have died as a result of human–elephant conflicts in Northeast India. Construction of electric fencing has failed to eliminate conflicts despite its initial success. When the fencing was erected, the elephants innovated an intelligent method of breaking fencing posts by holding the top of the wooden posts by their trunk and breaking at the middle by gently pushing their foot, thus avoiding the live wires.[26]
Carl Linnaeus first described the genus Elephas and an elephant from Ceylon under the binomial Elephas maximus in 1758.[27] In 1798, Georges Cuvier first described the Indian elephant under the binomial Elephas indicus.[28] In 1847, Coenraad Jacob Temminck first described the Sumatran elephant under the binomial Elephas sumatranus.[29] Frederick Nutter Chasen classified all three as subspecies of the Asian elephant in 1940.[30]
In 1950, Paules Edward Pieris Deraniyagala described the Borneo elephant under the trinomial Elephas maximus borneensis, taking as his type an illustration in the National Geographical Magazine, but not a living elephant in accordance with the rules of the International Code of Zoological Nomenclature.[31] 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.[32]
The population in Vietnam and Laos is tested to determine if it is a subspecies as well. This research is considered vital as there are less than 1300 wild Asian elephants remaining in Laos.[33] In addition, two extinct subspecies are considered to have existed:
Besides habitat loss and poaching, development such as border fencing along the India-Bangladesh border has become a major impediment to the free movement of elephants.[34]
Elephas maximus is listed on CITES Appendix I.[3]
The elephant plays an important part in the culture of the subcontinent and beyond, featuring prominently in Jataka tales and the Panchatantra. It plays 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 have been used in processions in Kerala where the animals are adorned with festive outfits.
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