Asian elephant | Smithsonian's National Zoo
Meet the Animals
Physical Description
Asian elephant skin is gray in color. Some parts of their skin sometimes lack color, especially on and around the ears, forehead and trunk. This de-pigmentation is believed to be controlled by genetics, nutrition and habitat, and generally develops as the elephant ages. Brownish to reddish hair covers the bodies of young elephants. The amount of hair reduces with age, and the color darkens.
Elephant skin varies from paper thin in some places, such as on the inside of the ears, to as thick as 1 inch (2.54 centimeters) in other places, such as around the back. Despite its thickness, the skin is sensitive, having a rich nerve supply. Elephants protect their skin from the sun and bugs by regularly covering themselves with dirt, sand and mud.
Elephants have large ears that function as cooling devices. There are many blood vessels on the inside. As elephants flap their ears on hot days, the blood in these veins cools, which then cools their brain and travels back through the body, reducing body temperature by several degrees.
Unlike other mammals, where the legs are in an angular position, the elephant's legs are stacked in an almost vertical position under the body. This positioning, along with the detailed anatomy of their long bones, provides a strong support for the animal's great weight. The vertical position of the limbs allows the elephant to remain standing for long periods without expending much energy. It also allows elephants to sleep while standing as well as while lying down.
In most mammals, the bones contain a narrow cavity. In elephants, this cavity is lacking. Instead, network of dense perforated bone occupies the space, which makes the bones stronger and able to withstand more pressure.
The elephant's skeleton is designed for mobility as well as strength. An elephant must have physical structures and coordinated muscular and neurological systems to accomplish survival skills like standing on their rear legs and climbing up and down steep slopes.
Elephants actually walk on their toes and have a thick fibrous pad on the bottom of each foot that acts as a shock absorber, protecting their leg and toe bones from jarring under their great weight and cushioning each step.
The trunk is a fusion of the nose and upper lip. It contains no bones, but is composed of muscles, blood and lymph vessels, nerves, little fat, connective tissues, skin, hair and bristles. Cartilage is found only at the base of the trunk, dividing the nostrils. The trunk has about 150,000 muscle units and tendons that provide the elephant precision as well as strength of movement.
The great dexterity of the trunk, which can perform movements of delicate precision, is due to thousands of often-tiny muscle units. These tend to be arranged either radially or longitudinally and by acting against one another, allow the trunk to be moved in any direction. Although so delicate in its movements, the trunk is also a very powerful organ that can lift heavy objects with ease.
Asian elephants have one small projection at the end of their trunk called a "finger," which aids with precision. Elephants use their trunks to take up water and squirt it into their mouths. The trunk is capable of performing many other functions as well, including: feeding, snorkeling, dusting, smelling, sifting, sorting, touching, sound production/communication, lifting, pushing, defense and offense. It can hold about 2 gallons (7.57 liters) of water. With their trunks, elephants "know" their world: their senses of smell and touch being very important.
All six sets of teeth are present in the skull at birth. They are, however, very small. Each successive set of teeth is larger, more complex, and lasts longer than the previous set. As a result, an elephant's skull grows throughout its lifetime to accommodate the new and ever-larger teeth. An elephant's age can be estimated by examining molar sequence and wear.
Tusks are modified upper incisors that grow throughout an individual's life at the rate of 2 to 3 inches (5.1 to 7.6 centimeters) a year. They are composed of ivory. Ivory is similar to bone, being made up mostly of calcium and phosphate. The tusk contains a pulp cavity, containing nerve tissues. In an adult animal, about two thirds of the tusk is visible while the remaining one third is embedded in the socket, or sulcus, in the cranium.
Newly developing tusks have a conical cap of smooth enamel that wears off. Not all elephants develop visible tusks; in the Asian species, only some males have large, prominent tusks. Most female and some male Asian elephants have small tusks, called tushes, which seldom protrude more than an inch or two from the lip line. Tushes are a slightly different composition than tusks. They are small and brittle, causing them to break easily. A significant number of adult Asian males are tuskless. The percentage of males with tusks varies by region; less than 10 percent in Sri Lanka to approximately 90 percent in India. This disparity may be a reflection of the intensity of past ivory hunting.
In the African species, generally, but not always, both the males and females have tusks. Tusks are extremely useful, multipurpose instruments. Elephants use them to: dig for water, salt, minerals and roots; to debark trees; as levers to manipulate objects in their environment; for rescuing calves; for threat displays; as weapons for defense and offense; as trunk rests; and as protection for the trunk.
Size
Slightly smaller than their African cousins, adult Asian elephants weigh on average between 6,000 and 12,000 pounds (2,750 and 5,420 kilograms). They typically stand 6 to 12 feet (1.8 to 3.8 meters) at the shoulder. Males are usually larger than females.
Native Habitat
Asian elephants are found in isolated pockets of India and Southeast Asia, including Sumatra and Borneo. Asian elephants were formerly widely distributed south of the Himalayas, throughout Southeast Asia and in China as far north as the Yangtze River.
Asian elephants considered forest animals; however, they have been observed to prefer zones that include intermittent open grassy glades. These zones contain transition areas with a great variety of species of plants between grass and forest, not available in dense woodlands. These zones also provide quick escape from the sun. Elephants are adaptable and can live in a variety of environments.
Elephants migrate as necessary to find habitat that contains sufficient vegetation and water to meet their enormous daily requirements. Although they are not territorial, they do move about within home ranges. The amount of movement within these ranges appears to be variable from region to region.
Data gathered by Smithsonian's National Zoo scientists from radio-collared wild elephants in Myanmar show that elephants typically walk less than one to four miles (1.6 to 6.4 kilometers) per day. The home range usually constitutes a loop or a circuit. Home ranges vary in size from six to 20 square miles (15 to 50 square km) to 190 to 580 square miles (500 to 800 square km). The differences depend on quantity and quality of the food and whether or not the area is occupied by bulls or by cows and their offspring. Home ranges of one family, clan or herd may overlap with another. Human activities such as agriculture have made seasonal migration difficult, creating much conflict between wild elephants and people.
Communication
Elephants communicate over long distances using low-pitched sounds that are barely audible to humans. These powerful infrasonic rumbles contain specific messages that can be heard and understood by other elephants more than two miles away. Scientists believe that an elephant's ability to converse over long distances is essential for its survival. Females in estrus make very low, long calls that bulls hone in on. Breeding herds also use low-frequency vocalizations to warn of predators. Adult bulls and cows have no enemies, except for humans, but young elephants are susceptible to attacks by tigers in the areas where their ranges overlap. When a predator appears, older members of the herd emit intense warning calls that prompt the rest of the herd to clump together for protection and then flee the scene.
Elephants possess a highly developed olfactory system. Scent is a valuable mode of communication because it can be long lasting and function over both short and long distances. Wind-born scents provide elephants with clues to the presence of other elephants or potential dangers. Using their trunk to smell another elephant's mouth, temporal gland, genitals, or urine/feces, the identity, sex and reproductive status of that elephant can be determined.
Elephants of all ages and both sexes touch one another frequently, often to communicate a greeting, excitement, competition, dominance, discipline, reassurance, play and reproductive status. The trunk is an especially important means of tactile communication
Food/Eating Habits
Asian elephants are herbivores. An elephant spends about three-quarters of each day eating or moving toward a food or water source. Feeding is not continuous, with three principal feeding bouts in the early morning, afternoon and night. Elephants tend to rest and nap during the hottest hours of the day. They feed primarily on grasses, but also consume large amounts of browse: leaves, roots, vines, twigs, shoots and bark as well as fruit. Cultivated crops such as bananas and sugar cane are also a favored food. Foraging herds can be very destructive to cropland or forest because they are capable of pushing down large trees in order to gather their foliage and bark. Unlike ruminants, elephants only assimilate about 44 percent of what they eat. Therefore, they must consume great amounts of food, about 165 to 330 pounds (74 to 150 kilograms) per day and about 50 gallons (189 liters) of water per day in the wild. A very large male might eat twice that.
The elephants at the Zoo are fed throughout the day to simulate their natural feeding pattern. Their diets are individually tailored to each animal's needs, taking into account health, age, activity level and metabolism. A typical diet for an adult female elephant could total about 135 pounds, consisting of about two and a half bales of hay (each bale weighs about 45 pounds or 20 kilograms), eight pounds of elephant chow, (an alfalfa based pellet that is nutrient dense, providing protein, vitamins and minerals), two pounds each of bran and oats, and ten pounds of fruits and vegetables, including sweet potatoes, carrots, and apples. Apple fiber pellets are fed as training reinforcement and browse is fed as available.
Social Structure
Their burrow systems range from simple to complex and they usually have several burrow systems, which they occupy in rotation for several months at a time. They spread out to forage independently, but maintain visual and vocal contact.
Reproduction and Development
Wild males and females reach sexual maturity between eight and 13 years of age. Females usually have their first birth in their mid-teens. Behavioral studies tell us that males are unlikely to father a calf until they are in their thirties, when they are best able to compete with older, larger males.
However, more recent DNA testing of African elephants suggests that young bulls may father calves more frequently than previously thought. By about the age of 30 most healthy males begin to experience a regular period of heightened sexual and aggressive activity called musth.
Musth is a massive rush of testosterone that makes the males aggressive and competitive. It also makes them especially attractive to females in estrus. During musth, a green fluid drips from the penis and is secreted from the elephant's temple. In human care both male and female elephants mature earlier than in the wild. The onset of musth in zoo elephants has come as early as eight years. This phenomenon is thought to be due to consistent quality nutrition and environmental conditions and lack of suppression or competition by older animals.
Females come into estrus about every 115 days. Gestation is between 20.5 and 22 months, the longest gestation period for any animal. Usually one calf, occasionally two, is born and weighs between 150 and 350 pounds (68 to 158 kilograms). There is an average birth interval of three to eight years, depending on environmental conditions. Calves stand and nurse soon after birth. By 6 months, calves begin feeding on vegetation. They also eat their mother's dung for several years, which contains nutrients as well as the symbiotic bacteria that aid in the digestion of cellulose. Weaning is a gradual process that may continue until the mother delivers another calf. Males leave their natal herd at sexual maturity, but females remain within the family unit throughout their lives.
Lifespan
Longevity of elephants is not well understood. Most of the information available comes from African elephants. Recent data from scientists studying wild African elephants suggests that they rarely live to 50 years old, with most living to their mid- to late 40s. The longevity record for an Asian elephant in captivity is 86 years. There is not enough consistent data available on wild Asian elephants to accurately estimate their life span; however, it is thought that Asian elephants typically live into their mid- to late 50s.
Asian elephants are endangered. At one time Asian elephants ranged from Syria and Iraq east across Asia south of the Himalayas to Indochina and the Malay Peninsula, north into China, and in Sri Lanka, Sumatra, Borneo and possibly Java. The Western Forest Complex in Thailand is the largest remaining area of protected forest in Southeast Asia and home to more than a third of Thailand's wild elephants. India by far has the largest population of elephants for a single country with almost half of the total population of Asian elephants in the world living within its borders.
Because elephants require much larger areas of natural range than many other terrestrial mammals, they are often the first species to suffer the consequences of habitat fragmentation and destruction. Elephants are also considered a pest and a danger in areas of agriculture, especially populations surrounded by cultivated land. Crop raiding is frequent and can create situations that can lead to elephant deaths as well as human deaths. Palm oil plantations, primarily in Malaysia and Indonesia are rapidly causing deforestation. The use of slash and burn clearing and industrial planting techniques is not uncommon. This is greatly decreasing the land available for elephant habitats in these regions.
Elephant poaching for ivory does not threaten the Asian elephant to as great an extent as it does the African elephant because many male Asian elephants are tuskless. However, poaching of tuskers in southern India for both ivory and meat is still a serious problem and has had a radical effect on breeding patterns. For example, in the Periyar Tiger Reserve in south India, poaching has left one adult male elephant for every 100 females. The result is that very few cows mate with bulls. Fewer than 33 percent of adult females in the reserve have calves less than five years old. In contrast, in the Rajaji National Park the sex ratio is one male for every two females. Ninety percent of females are accompanied by a calf.
In some countries, the government provides compensation for crop damage or deaths caused by elephants, but there is still often strong political pressure on wildlife authorities to eliminate elephants near populated regions. Increasingly there is pressure on palm oil plantations and other practices such as forestry to become certified. Certification qualifications have specific requirements to reduce deforestation, emissions and wildlife conflicts. However, as human populations increase, elephant-human conflicts are likely to rise. Experts already consider such confrontations to be the leading cause of elephant deaths in Asia. In India about 300 people and 200 elephants per year die through poaching, crop protection incidents or automobile related accidents.
Because of these threats, Asian elephant numbers are estimated to be between 30,000 and 50,000 animals. This estimate has such a wide range due to the extreme difficulty involved in trying to survey a population that is difficult to find and continuously changes. The low range is the definite and the upper range is the possible number, with the actual count being somewhere in the middle.
It is thought that as many as one third of the total population of Asian elephants are held in captivity throughout Southeast Asia, most as work animals. The British used captive animals to open the forests to logging in colonial times. The decline of the logging industry has led to many out-of-work elephants and mahouts.
The future of elephants largely depends on the continuation of the ivory ban, habitat preservation, devising ways for people and elephants to co-exist together and successful zoo breeding programs around the world. Often one of the most successful methods of conserving a species is to view it as a sustainable resource. While it is certainly not feasible to use elephants for their ivory, they can be seen as a resource in ecotourism as well as in logging operations that have historically had very little negative impact on their forest environment. Due to its need for large areas of suitable habitat, the Asian elephant is considered a flagship' or umbrella species, whose survival would help maintain biological diversity and ecological integrity over extensive areas. Asian elephants have great religious significance throughout their range, which has contributed significantly to their conservation.
Conservation Projects