Tuesday, 29 May 2012

Asian Elephant



The Asian or Asiatic elephant (Elephas maximus) is the only living species of the genus Elephas and is 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. Asian elephants are the largest living land animals in Asia.
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. In 2003, the wild population was estimated at between 41,410 and 52,345 individuals.
Asian elephants are rather long-lived, with a maximum recorded life span of 86 years.
Contrary to popular belief, the Asian elephant has never been domesticated, in the sense that it has never been bred over multiple generations with selected traits specifically to serve human needs. This term is often conflated with taming or training, a process by which a wild-caught animal may be induced to accept human commands. Trained captive elephants have nevertheless 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.

Characteristics


Illustration of an elephant skeleton

Asian elephant skeleton

the Borneo elephant is smaller than other Asian elephant subspecies, and has relatively large ears, a longer tail, and straighter tusks.
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.

Size

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. One extraordinarily large elephant living in captivity at the Oregon Zoo, Packy, weighed 6,590 kilograms (14,530 lb) in 2008.
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.
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.
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.

Trunk

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.
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.
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.

Tusks


From National Museum, Kolkatta
 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.
Female Asian elephants usually lack 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.
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 10412 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).

Skin

Asian-elephant-ueno2009-video.ogg
An Asian Elephant fans itself with dust at Ueno Zoo in Tokyo, Japan.
   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).

Intelligence

Asian elephants are highly intelligent and self-aware. 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 are reported to go to safer ground during natural disasters like tsunamis and earthquakes, although there have been no scientific records of this.

Distribution and habitat

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 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.
Three subspecies are recognized:

  • the Sri Lankan Elephant lives in Sri Lanka;
  • the Indian Elephant lives in mainland Asia: India, Nepal, Bangladesh, Bhutan, Myanmar, Thailand, Malay Peninsular, Vietnam, Cambodia, Laos, and China;
  • the Sumatran Elephant lives in Sumatra and Borneo.
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.

Ecology and behavior


Indian elephants at Mudumalai Tiger Reserve

A herd of Indian elephants in the Jim Corbett National Park, India
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'.
Cow-calf unit sizes generally tend to be small, typically consisting of 3 adult females who are most likely related, and their offspring; however, larger groups containing as many as 15 adult females may occur. There can also be seasonal aggregations containing over 100 individuals at a time, including calves and sub-adults. Until recently it was thought that Asian elephants, like African elephants, typically follow the leadership of older adult females, or matriarchs. But recently it has been shown that females can form extensive and very fluid social networks, with a lot of individual variation in the degree of gregariousness. Social ties generally tend to be weaker than in African elephants.
Elephants are crepuscular. They are megaherbivores and consume up to 150 kg (330 lb) of plant matter per day. 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. They browse more in the dry season with bark constituting a major part of their diet in the cool part of that season.
They drink at least once a day and are never far from a permanent source of fresh water. 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.
Elephants are able to distinguish low amplitude sounds. They use infrasound to communicate; this was first noted by the Indian naturalist M. Krishnan and later studied by Katharine Payne.
A healthy adult Asian elephant is not known to have natural predators, but there have been rare instances of tigers preying on young or weak elephants.

Reproduction


Baby elephant Gabi and his mother Tamar at the Jerusalem Biblical Zoo, 2007
Bulls will fight one another to get access to estrous 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 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.
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.
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.

Interaction with humans


Mahouts washing an elephant, Thrissur, Kerala.
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, trained 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.

In captivity


Used for tourism throughout Asia

At this elephant training camp, captive elephants are taught to handle logs.

The elephant namely Soman at the elephant training centre, Konni, Pathanamthitta

Sri Lankan elephants at Esala Perahera
 
The first historical record of the taming of Asian elephants was in Harappan times. 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.
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.

Threats

The major threat facing the Asian elephant today is habitat loss resulting from deforestation. Other causes include poaching for ivory, isolation of elephant populations and human-elephant conflict.
Development such as border fencing along the India-Bangladesh border has become a major impediment to the free movement of elephants.

Human-elephant conflict

Human-elephant conflicts arise due to competition between humans and elephants for space and resources. A range of drivers influence human-elephant conflict, which can be categorized into:

  • ultimate causes such as population growth and development projects;
  • proximate causes such as illegal encroachment into elephant habitat, deforestation, and poor environmental governance.
In India alone, over 400 people are killed by elephants every year, affecting nearly 500,000 families across the country. Moreover, elephants are known to destroy crops worth up to US$ 2-3 million annually.
This has major impacts both for the welfare and livelihoods of local communities, but also for the future conservation of this species. In an extreme scenario in Assam, northeast India more than 1,150 humans and 370 elephants died as a result of human-elephant conflict between 1980 and 2003.

Conservation

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

  • habitat conservation at landscape scales;
  • generating public awareness of conservation issues;
  • mobilization as a popular cultural icon both in India and the West.

Taxonomy

Carl Linnaeus first described the genus Elephas and an elephant from Ceylon under the binomial Elephas maximus in 1758. In 1798, Georges Cuvier first described the Indian elephant under the binomial Elephas indicus. In 1847, Coenraad Jacob Temminck first described the Sumatran elephant under the binomial Elephas sumatranus. Frederick Nutter Chasen classified all three as subspecies of the Asian elephant in 1940.
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. 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.
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. In addition, two extinct subspecies are considered to have existed:
  • The Chinese Elephant is sometimes separated as E. m. rubridens (pink-tusked elephant); it disappeared after the 14th century BC.
  • The Syrian Elephant (E. m. asurus), the westernmost and the largest subspecies of the Asian elephant, became extinct around 100 BC. This population, along with the Indian elephant, was considered the best war elephant in antiquity, and was found superior to the smallish North African Elephant (Loxodonta africana pharaoensis) used by the armies of Carthage.

In culture


A folio from the Hastividyarnava manuscript
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.
The elephant is depicted in several Indian manuscripts and treatises. Notable amongst these is the Matanga Lila of Rameswara Pandita and the Hastividyarnava of Sukumar Barkaith. The latter manuscript is from Assam in northeast India.