Elephants are large land mammals in two genera of the family Elephantidae: Elephas and Loxodonta. Three species of elephant are living today: the African bush elephant, the African forest elephant and the Asian elephant (also known as the Indian elephant). All other species and genera of Elephantidae are extinct, some since the last ice age although dwarf forms of mammoths may have survived as late as 2,000 BCE.[1] Elephants and other Elephantidae were once classified with other thick-skinned animals in a now invalid order, Pachydermata.
Elephants are the largest land animals now living.[2] The elephant's gestation period is 22 months, the longest of any land animal. At birth it is common for an elephant calf to weigh 120 kilograms (260 lb). They typically live for 50 to 70 years, but the oldest recorded elephant lived for 82 years.[3] The largest elephant ever recorded was shot in Angola in 1956. This male weighed about 24,000 lb (11,000 kg),[4] with a shoulder height of 3.96 metres (13.0 ft), a metre (yard) taller than the average male African elephant.[5] The smallest elephants, about the size of a calf or a large pig, were a prehistoric species that lived on the island of Crete during the Pleistocene epoch.[6]
Elephants are a symbol of wisdom in Asian cultures and are famed for their memory and intelligence, where they are thought to be on par with cetaceans[7] and hominids.[8] Aristotle once said the elephant was "the beast which passeth all others in wit and mind".[9] The word "elephant" has its origins in the Greek ἐλέφας, meaning "ivory" or "elephant".[10]
According to observations, healthy adult elephants have no natural predators,[11] although lions may take calves or weak individuals.[12][13] They are, however, threatened by human intrusion and poaching.
| Elephant Temporal range: Pliocene–Recent | |
|---|---|
 | |
| Asian and African elephants. | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Vertebrata |
| Class: | Mammalia |
| Superorder: | Afrotheria |
| Order: | Proboscidea |
| Family: | Elephantidae Gray, 1821 |
| Genus: | Elephas, Loxodonta for Elephas: Linnaeus, 1758; for Loxodonta: Anonymous, 1827; for Palaeoloxodon, taxonomic source not mentioned in Wikipedia article[14] |
| Subgenus: | Palaeoloxodon †, also considered genus[15] |
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Etymology
Olifant and its variations (ex. oliphant, olyphant) are archaic spellings of elephant. Aside from elephants, the word has been used to refer to ivory, elephant tusks, musical horns made of elephant tusks, or a musical instrument resembling such horns.
It appears in Middle English as olifant or olifaunt, and was borrowed from Medieval French olifanz. The French word owes something to both Old High German olbenta "camel", and to Latin elephantus "elephant", a word of Greek origin.[16] OHG olbenta is a word of old Germanic origin; cf. Gothic ulbandus also meaning "camel". But the form of the OHG and Gothic words suggests it is also a borrowing, perhaps indeed directly or indirectly from Greek "ἐλέφας" (elephas), which in Homer only meant "ivory" but from Herodotus and on the word also referred to the animal.[17] The earliest attested form of the word is the Mycenaean Greek e-re-pa-to, written in Linear B syllabic script.[18]
Taxonomy and evolution
The African elephant genus contains two or, arguably, three living species; whereas the Asian elephant species is the only surviving member of the Asian elephant genus, but can be divided into four subspecies. The African and the Asian elephant diverged from a common ancestor some 7.6 million years ago.[19]
African elephant
The Elephants of the genus Loxodonta, known collectively as African elephants, are currently found in 37 countries in Africa.
African elephants are distinguished from Asian elephants in several ways, the most noticeable being their much larger ears. Also, the African elephant is typically larger than the Asian elephant and has a concave back. In Asian elephants, only males have tusks, but both males and females of African elephants have tusks and are usually less hairy than their Asian cousins.
African elephants have traditionally been classified as a single species comprising two distinct subspecies, namely the savanna elephant (Loxodonta africana africana) and the forest elephant (Loxodonta africana cyclotis), but recent DNA analysis suggests that these may actually constitute distinct species.[20] This split is not universally accepted by experts.[21] A third species of African elephant has also been proposed.[22]
The authors of an analysis of nuclear DNA extracted from "African savanna elephant, African forest elephant, Asian elephant, the extinct American mastodon, and the woolly mammoth" concluded in 2010 that African savanna and forest elephants are indeed separate species:
- We unequivocally establish that the Asian elephant is the sister species to the woolly mammoth. A surprising finding from our study is that the divergence of African savanna and forest elephants—which some have argued to be two populations of the same species—is about as ancient as the divergence of Asian elephants and mammoths. Given their ancient divergence, we conclude that African savanna and forest elephants should be classified as two distinct species.[23]
This reclassification has implications for conservation. If there are two separate species, each will be less abundant (particularly the rarer) and could be more endangered than a more numerous and wide-ranging single species. There is also a potential danger that if the forest elephant is not explicitly listed as an endangered species, poachers and smugglers might be able to evade the law forbidding trade in endangered animals and their products.
The forest elephant and the savanna elephant can hybridize (interbreed), though their preferences for different terrains reduce such opportunities. As the African elephant has only recently been recognized to comprise two separate species, groups of captive elephants have not been comprehensively classified and some could well be hybrids.
Under the new two species classification, Loxodonta africana refers specifically to the savanna elephant, the largest of all elephants. It is the largest land animal, with males standing 3.2 metres (10 ft) to 4 metres (13 ft) at the shoulder and weighing 3,500 kilograms (7,700 lb) up to a reported 12,000 kilograms (26,000 lb).[24] The female is smaller, standing about 3 metres (9.8 ft) at the shoulder.[25] Most often, savanna elephants are found in open grasslands, marshes, and lakeshores. They range over much of the savanna zone south of the Sahara.
The other putative species, the forest elephant (Loxodonta cyclotis), is usually smaller and rounder, and its tusks thinner and straighter compared with the savanna elephant. The forest elephant can weigh up to 4,500 kilograms (9,900 lb) and stand about 3 metres (10 ft) tall. Much less is known about these animals than their savanna cousins, because environmental and political obstacles make them difficult to study. Normally, they inhabit the dense African rain forests of central and western Africa, although occasionally they roam the edges of forests, thus overlapping the savanna elephant home ranges and hybridizing. In 1979, Iain Douglas-Hamilton estimated the continental population of African elephants at around 1.3 million animals.[26] This estimate is controversial and is believed to be a gross overestimate,,[27] but it is very widely cited and has become a de facto baseline that continues to be incorrectly used to quantify downward population trends in the species. Through the 1980s, Loxodonta received worldwide attention due to the dwindling numbers of major populations in East Africa, largely as a result of poaching. According to IUCN’s African Elephant Status Report 2007,[28] there are between 470,000 and 690,000 African elephants in the wild. Although this estimate only covers about half of the total elephant range, experts do not believe the true figure to be much higher, as it is unlikely that large populations remain to be discovered.[29] By far, the largest populations are now found in southern and eastern Africa, which together account for the majority of the continental population. According to a recent analysis by IUCN experts, most major populations in eastern and southern Africa are stable or have been steadily increasing since the mid-1990s, at an average rate of 4.5% per year.[29][30]
Elephant populations in West Africa, on the other hand, are generally small and fragmented, and only account for a small proportion of the continental total.[31] Much uncertainty remains as to the size of the elephant population in central Africa, where the prevalence of forest makes population surveys difficult, but poaching for ivory and bushmeat is believed to be intense through much of the region.[32] South African elephant population more than doubled, rising from 8,000 to over 20,000, in the thirteen years after a 1995 ban on the trade in elephant ivory.[33] The ban on the ivory trade in southern Africa (but not elsewhere) was lifted in February 2008, sparking controversy among environmental groups.[citation needed]
Asian elephant
The Asian elephant, Elephas maximus, is smaller than the African. It has smaller ears, and typically, only the males have large external tusks.
The world population of Asian elephants—also called Indian elephants—is estimated to be around 60,000, about a tenth of the number of African elephants. More precisely, it is estimated that there are between 38,000 and 53,000 wild elephants and between 14,500 and 15,300 domesticated elephants in Asia, with perhaps another 1,000 scattered around zoos in the rest of the world.[34] The Asian elephants' decline has possibly been more gradual than the African and caused primarily by poaching and habitat destruction by human encroachment.
Several subspecies of Elephas maximus have been identified, using morphometric data and molecular markers. Elephas maximus maximus (Sri Lankan elephant) is found only on the island of Sri Lanka. It is the largest of the Asians. There are an estimated 3,000–4,500 members of this subspecies left today in the wild, although no accurate census has been carried out recently. Large males can weigh upward to 5,400 kg (12,000 lb) and stand over 3.4 m (11 ft) tall. Sri Lankan males have very large cranial bulges, and both sexes have more areas of depigmentation than other Asians. Typically, their ears, face, trunk, and belly have large concentrations of pink-speckled skin. There is an orphanage for elephants in Pinnawala, Sri Lanka, which plays a large role in protecting the Sri Lankan elephant from extinction.
Elephas maximus indicus (Indian elephant) makes up the bulk of the Asian elephant population. Numbering approximately 36,000, these elephants are lighter grey in colour, with depigmentation only on the ears and trunk. Large males will ordinarily weigh only about 5,000 kg (11,000 lb), but are as tall as the Sri Lankan. The mainland Asian can be found in 11 Asian countries, from India to Indonesia. They prefer forested areas and transitional zones, between forests and grasslands, where greater food variety is available.
The Sumatran elephant, Elephas maximus sumatranus, found only on Sumatra, is smaller than the Indian elephant. Population estimates for this group range from 2,100 to 3,000 individuals. It is very light grey in colour and has less depigmentation than the other Asians, with pink spots only on the ears. Mature Sumatrans will usually only measure 1.7–2.6 m (5.6–8.5 ft) at the shoulder and weigh less than 3,000 kg (6,600 lb). It is considerably smaller than its other Asian (and African) cousins and exists only on the island of Sumatra, usually in forested regions and partially wooded habitats.
In 2003, a further subspecies was identified on Borneo. Named the Borneo pygmy elephant, it is smaller and tamer than any other Asian elephants. It also has relatively larger ears, longer tail and straighter tusks.
Physical characteristics
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Trunk
The proboscis, or trunk, is a fusion of the nose and upper lip, elongated and specialized to become the elephant's most important and versatile appendage. African elephants are equipped with two fingerlike projections at the tip of their trunk, while Asians have only one. The elephant's trunk is sensitive enough to pick up a single blade of grass, yet strong enough to rip the branches off a tree.
Most herbivores (plant eaters, like the elephant) possess teeth adapted for cutting and tearing off plant materials. However, except for the very young or infirm, elephants always use their trunks to tear up their food and then place it in their mouths. They will graze on grass or reach up into trees to grasp leaves, fruit, or entire branches. If the desired food item is too high up, the elephant will wrap its trunk around the tree or branch and shake its food loose or sometimes simply knock the tree down altogether.
The trunk is also used for drinking. Elephants suck water up into the trunk—up to 14 litres (15 quarts) at a time—and then blow it into their mouths. Elephants also suck up water to spray on their bodies during bathing. On top of this watery coating, the animals will then spray dirt and mud, which dries and acts as a protective sunscreen. When swimming, the trunk makes an excellent snorkel.[35][36]
This appendage also plays a key role in many social interactions. Familiar elephants will greet each other by entwining their trunks, much like a handshake. They also use them while play-wrestling, caressing during courtship and mother-child interactions, and for dominance displays; a raised trunk can be a warning or threat, while a lowered trunk can be a sign of submission. Elephants can defend themselves very well by flailing their trunks at unwanted intruders or by grasping and flinging them.
An elephant also relies on its trunk for its highly developed sense of smell. By raising the trunk up in the air and swiveling it from side to side, like a periscope, it can determine the location of friends, enemies, and food sources.[citation needed]
Some elephants have been afflicted by floppy trunk syndrome.
Tusks
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The tusks of an elephant are its second upper incisors. Tusks grow continuously; an adult male's tusks grow about 18 cm (7 in) a year. Tusks are used to dig for water, salt, and roots; to debark trees to eat the bark; to dig into baobab trees to get at the pulp inside; and to move trees and branches when clearing a path. In addition, they are used for marking trees to establish territory, and occasionally as weapons.
Like humans who are typically right- or left-handed, elephants are usually right- or left-tusked. The dominant tusk, called the master tusk, is generally shorter and more rounded at the tip from wear. Both male and female African elephants have large tusks that can reach over 3 m (10 ft) in length and weigh over 90 kg (200 lb). In the Asian species, only the males have large tusks. Female Asians have tusks which are very small or absent altogether. Asian males can have tusks as long as the much larger Africans, but they are usually much slimmer and lighter; the heaviest recorded is 39 kg (86 lb). The tusk of both species is mostly made of calcium phosphate in the form of apatite. As a piece of living tissue, it is relatively soft (compared with other minerals such as rock), and the tusk, also known as ivory, is strongly favoured by artists for its carvability. The desire for elephant ivory has been one of the major factors in the reduction of the world's elephant population.
Some extinct relatives of elephants had tusks in their lower jaws in addition to their upper jaws, such as Gomphotherium, or only in their lower jaws, such as Deinotherium.[37]
Teeth
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Elephants' teeth are very different from those of most other mammals. Over their lives they usually have 28 teeth. These are:
- The two upper second incisors: these are the tusks.
- The milk precursors of the tusks.
- 12 premolars, 3 in each side of each jaw.
- 12 molars, 3 in each side of each jaw.
This gives elephants a dental formula of: 
Unlike most mammals, which grow baby teeth and then replace them with a permanent set of adult teeth, elephants have cycles of tooth rotation throughout their entire lives. The tusks have milk precursors, which fall out quickly and the adult tusks are in place by one year of age, but the chewing teeth are replaced five[38] or, very rarely, six[39] times in an elephant's lifetime.
Only four chewing teeth (premolars and/or molars), one on each side of each jaw, are in primary use at any given time (or two, as one replaces the other at each location). Adult teeth do not replace milk teeth by emerging from the jaws vertically as human teeth do. Instead, new teeth grow in at the back of the mouth, pushing older teeth toward the front, where the latter break off in pieces until they are gone. In African elephants, the first two sets of chewing teeth (premolars) are in place when an elephant is born. The first chewing tooth on each side in each jaw falls out when the elephant is about two years old. The second set of chewing teeth falls out when the elephant is about six years old. The third set is lost at 13 to 15 years of age, and set four lasts to approximately 28 years of age. The fifth set of chewing teeth (molars) lasts until the elephant is in its early 40s. The sixth (and usually final) set must last the elephant the rest of its life. If an elephant lives to more than 60 years of age, the last set of molars is worn to stumps, and it can no longer feed properly. Moss reports a female elephant in its sixties whose final set of molars were worn smooth and about one-quarter of their original size and who survived "with extra chewing and longer feeding bouts." Abscesses of chewing teeth, as well as of tusks and jaws, are common in elephants, and may lead to premature death.[40]
Tusks in the lower jaw are also second incisors. These grew out large in Deinotherium and some mastodons, but in modern elephants they disappear early without erupting.
Skin
Elephants are colloquially called pachyderms (from their original scientific classification), which means thick-skinned animals. An elephant's skin is extremely tough around most parts of its body and measures about 2.5 centimetres (1.0 in) thick. However, the skin around the mouth and inside of the ear is paper-thin. Normally, the skin of an Asian is covered with more hair than its African counterpart. This is most noticeable in the young. Asian calves are usually covered with a thick coat of brownish red fuzz. As they get older, this hair darkens and becomes more sparse, but it will always remain on their heads and tails.
The species of elephants are typically greyish in colour, but the Africans very often appear brown or reddish from wallowing in mud holes of colored soil. Wallowing is an important behaviour in elephant society. Not only is it important for socialization, but the mud acts as a sunscreen, protecting its skin from harsh ultraviolet radiation. Although tough, an elephant's skin is very sensitive. Without regular mud baths to protect it from burning, as well as from insect bites and moisture loss, an elephant's skin would suffer serious damage. After bathing, the elephant will usually use its trunk to blow soil on its body to help dry and bake on its new protective coat. As elephants are limited to smaller and smaller areas, there is less water available, and local herds will often come too close over the right to use these limited resources.
Wallowing also aids the skin in regulating body temperatures. Elephants have difficulty in releasing heat through the skin because, in proportion to their body size, they have very little of it. The ratio of an elephant's mass to the surface area of its skin is many times that of a human. Elephants have even been observed lifting up their legs to expose the soles of their feet, presumably in an effort to expose more skin to the air. Since wild elephants live in very hot climates, they must have other means of getting rid of excess heat.
Legs and feet
An elephant's legs are great straight pillars, as they must be to support its bulk. The elephant needs less muscular power to stand because of its straight legs and large pad-like feet. For this reason, an elephant can stand for very long periods of time without tiring. In fact, African elephants rarely lie down unless they are sick or wounded. Indian elephants, in contrast, lie down frequently.
The feet of an elephant are nearly round. African elephants have three nails on each hind foot, and four on each front foot. Indian elephants have four nails on each hind foot and five on each front foot. Beneath the bones of the foot is a tough, gelatinous material that acts as a cushion or shock absorber. Under the elephant's weight, the foot swells, but it gets smaller when the weight is removed. An elephant can sink deep into mud, but can pull its legs out readily because its feet become smaller when they are lifted.[citation needed]
Elephants swim well, but cannot trot, jump, or gallop. They do have two gaits: a walk and a faster gait that is similar to running.
In walking, the legs act as pendulums, with the hips and shoulders rising and falling while the foot is planted on the ground. With no "aerial phase", the faster gait does not meet all the criteria of running, as elephants always have at least one foot on the ground. However, an elephant moving fast uses its legs much like a running animal, with the hips and shoulders falling and then rising while the feet are on the ground. In this gait, an elephant will have three feet off the ground at one time. As both of the hind feet and both of the front feet are off the ground at the same time, this gait has been likened to the hind legs and the front legs taking turns running.[41] Tests at the Thai Elephant Conservation Centre are reported to show that fast-moving elephants 'run' with their front legs, but 'walk' with their hind legs.[42]
Although they start this "run" at only 8 km/h,[43] elephants have been reported to reach speeds up to 40 km/h (25 mph),[44] all the while using the same gait. In tests at the Thai Elephant Conservation Centre, the fastest elephants reached a top speed of 18 km/h (11 mph).[42] At this speed, most other four-legged creatures are well into a gallop, even accounting for leg length. Spring-like kinetics could explain the difference between the motion of elephants and other animals.[45]
Ears
The large flapping ears of an elephant are also very important for temperature regulation. Elephant ears are made of a very thin layer of skin stretched over cartilage and a rich network of blood vessels. On hot days, elephants will flap their ears constantly, creating a slight breeze. This breeze cools the surface blood vessels, and then the cooler blood gets circulated to the rest of the animal's body. The hot blood entering the ears can be cooled as much as 10 °F (6 °C) before returning to the body. Differences in the ear sizes of African and Asian elephants can be explained, in part, by their geographical distribution. Africans originated and stayed near the equator, where it is warmer. Therefore, they have bigger ears. Asians live farther north, in slightly cooler climates, and thus have smaller ears.
The ears are also used in certain displays of aggression and during the males' mating period. If an elephant wants to intimidate a predator or rival, it will spread its ears out wide to make itself look more massive and imposing. During the breeding season, males give off an odor from the musth gland located behind their eyes. Joyce Poole, a well-known elephant researcher, has theorized that the males will fan their ears in an effort to help propel this "elephant cologne" great distances.[46]
Biology and behavior
Evolution
The earliest known ancestors of modern-day elephants evolved about 60 million years ago. The ancestor of the elephants from 37 million years ago was aquatic and had a similar lifestyle to a hippopotamus.[47]
Social behavior
Elephants live in a structured social order. The social lives of male and female elephants are very different. The females spend their entire lives in tightly knit family groups made up of mothers, daughters, sisters, and aunts. These groups are led by the eldest female, or matriarch. Adult males, on the other hand, live mostly solitary lives.
The social circle of the female elephant does not end with the small family unit. In addition to encountering the local males that live on the fringes of one or more groups, the female's life also involves interaction with other families, clans, and subpopulations. Most immediate family groups range from five to fifteen adults, as well as a number of immature males and females. When a group gets too big, a few of the elder daughters will break off and form their own small group. They remain very aware of which local herds are relatives and which are not.
The life of the adult male is very different. As he gets older, he begins to spend more time at the edge of the herd, gradually going off on his own for hours or days at a time. Eventually, days become weeks, and somewhere around the age of fourteen, the mature male, or bull, sets out from his natal group for good. While males do live primarily solitary lives, they will occasionally form loose associations with other males. These groups are called bachelor herds. The males spend much more time than the females fighting for dominance with each other. Only the most dominant males will be permitted to breed with cycling females. The less dominant ones must wait their turns. It is usually the older bulls, forty to fifty years old, that do most of the breeding.
The dominance battles between males can look very fierce, but typically they inflict very little injury. Most of the bouts are in the form of aggressive displays and bluffs. Ordinarily, the smaller, younger, and less confident animal will back off before any real damage can be done. However, during the breeding season, the battles can get extremely aggressive, and the occasional elephant is injured. During this season, known as musth, a bull will fight with almost any other male it encounters, and it will spend most of its time hovering around the female herds, trying to find a receptive mate.
Mating behavior
The mating season is short and females are only able to conceive for a few days each year. She will detach herself from the herd. The scent of the female (cow) elephant in heat (or estrus) attracts the male and she also uses audible signals to attract the male. As the female can usually outrun the male, she does not have to mate with every male that approaches her.
The male initiates the courtship and the female ignores him for several minutes. He then stops and starts again. Elephants display a range of affectionate interactions, such as nuzzling, trunk intertwining, and placing their trunks in each other's mouths (image 2).
In a rarely observed display of his affection, he may drape his trunk outside of his tusks during the ritual (image 1). The interactions may last for 20–30 minutes and do not necessarily result in the male mounting the female, though he may demonstrate arousal during the ritual.
The female elephant is not passive in the ritual and uses the same techniques as the male.
African as well as Asiatic males will engage in same-sex bonding and mounting. The encounters are analogous to heterosexual bouts, one male often extending his trunk along the other's back and pushing forward with his tusks to signify his intention to mount. Unlike heterosexual relations, which are always of a fleeting nature, those between males result in a "companionship", consisting of an older individual and one or two younger, attendant males. Same-sex relations are common and frequent in both sexes, with Asiatic elephants in captivity devoting roughly 46% of sexual encounters to same-sex activity.[48]
Rogue elephant is a term for a lone, violently aggressive wild elephant. It is a calque of the Sinhala term hora aliya. Its introduction to English has been attributed by the Oxford English Dictionary to Sir James Emerson Tennent, but this usage may have been predated by William Sirr.
Intelligence
With a mass just over 5 kg (11 lb), elephant brains are larger than those of any other land animal. A wide variety of behaviours associated with intelligence have been attributed to elephants, including those associated with grief, making music, art, altruism, allomothering, play, use of tools,[49] compassion and self-awareness.[50] Elephants may be on a par with other intelligent species, such as cetaceans[7] and nonhuman primates.[8] The largest areas in the elephant brain are those responsible for hearing, smell and movement coordination.
Senses
Elephants have well innervated trunks, and an exceptional sense of hearing and smell. The hearing receptors reside not only in ears, but also in trunks that are sensitive to vibrations, and most significantly feet, which have special receptors for low frequency sound and are exceptionally well innervated. Elephants communicate by sound over large distances of several kilometers partly through the ground, which is important for their social lives. Elephants are observed listening by putting trunks on the ground and carefully positioning their feet.
The eyesight of elephants is relatively poor.
Self-awareness
Mirror self recognition is a test of self-awareness and cognition used in animal studies. A mirror was provided and visible marks were made on the elephant. The elephants investigated these marks, which were visible only via the mirror. The tests also included invisible marks to rule out the possibility of their using other senses to detect these marks. This shows that elephants recognize the fact that the image in the mirror is their own self, and such abilities are considered the basis for empathy, altruism and higher social interactions. This ability has also been demonstrated in humans, apes, bottlenose dolphins,[51] and magpies.[52]
Communication
Elephants make a number of sounds when communicating. Elephants are famous for their trumpet calls, which are made when the animal blows through its nostrils. Trumpeting is usually made during excitement. Its use varies from startlement to a cry of help to rage. Elephants also make rumbling growls when greeting each other. The growl becomes a bellow when the mouth is open and a bellow becomes a moan when prolonged. This can escalate with a roar when threatening another elephant or another animal.
Elephants can communicate over long distances by producing and receiving low-frequency sound (infrasound), a sub-sonic rumbling, which can travel in the air and through the ground much farther than higher frequencies. These calls range in frequency from 15–35 Hz and can be as loud as 117 dB, allowing communication for many kilometres, with a possible maximum range of around 10 km.[53] This sound can be felt by the sensitive skin of an elephant's feet and trunk, which pick up the resonant vibrations much as the flat skin on the head of a drum. To listen attentively, every member of the herd will lift one foreleg from the ground, and face the source of the sound, or often lay its trunk on the ground. The lifting presumably increases the ground contact and sensitivity of the remaining legs. This ability is thought also to aid their navigation by use of external sources of infrasound. Discovery of this new aspect of elephant social communication and perception came with breakthroughs in audio technology, which can pick up frequencies outside the range of the human ear. Pioneering research in elephant infrasound communication was done by Katy Payne, of the Elephant Listening Project,[54] and is detailed in her book Silent Thunder. Though this research is still in its infancy, it is helping to solve many mysteries, such as how elephants can find distant potential mates, and how social groups are able to coordinate their movements over extensive range.[53] Joyce Poole has also begun decoding elephant utterances that have been recorded over many years of observation, hoping to create a lexicon based on a systematic catalogue of elephant sounds.[55]
Diet
Elephants are herbivores, and spend up to 16 hours a day eating plants. Their diets are highly variable, both seasonally and across habitats and regions. Elephants are primarily browsers, feeding on the leaves, bark, and fruits of trees and shrubs, but they may also eat considerable grasses and herbs. As is true for other nonruminant unglulates, elephants only digest approximately 40% of what they eat.[56] They make up for their digestive systems' lack of efficiency in volume. An adult elephant consumes 140–270 kg (300–600 lb) of food a day.
Reproduction and life cycle
Elephant calves
Female elephant social life revolves around breeding and raising of the calves. A female will usually be ready to breed around the age of thirteen, when she comes into estrus, a short phase of receptiveness lasting a couple of days, for the first time. Females announce their estrus with smell signals and special calls.
Females prefer bigger, stronger, and, most importantly, older males. Such a reproductive strategy tends to increase their offspring's chances of survival.
After a twenty-two-month pregnancy, the mother gives birth to a calf that weighs about 115 kg (250 lb) and stands over 75 cm (2.5 ft) tall. Elephants have a very long development. As is common with more intelligent species, they are born with fewer survival instincts than many other animals. Instead, they rely on their elders to teach them what they need to know. Today, however, the pressures humans have put on the wild elephant populations, from poaching to habitat destruction, mean that the elderly often die at a younger age, leaving fewer teachers for the young. The consequences of this for the next generation are not known.
A new calf is usually the center of attention for herd members. Adults and most of the other young will gather around the newborn, touching and caressing it with their trunks. The baby is born nearly blind and at first relies almost completely on its trunk to discover the world around it.
Elephants within a herd are usually related, and all members of the tightly-knit female group participate in the care and protection of the young. After the initial excitement, the mother will usually select several full-time baby-sitters, or "allomothers", from her group. An elephant is considered an allomother when she is not able to have her own calf. The more allomothers, the better the calf's chances of survival. A benefit of being an allomother is she can gain experience or receive assistance when caring for her own calf. According to Cynthia Moss, a well known researcher, these allomothers will help in all aspects of raising the calf.[57] They walk with the young as the herd travels, helping the calves along if they fall or get stuck in the mud. The more allomothers a calf has, the more free time its mother has to feed herself. Providing a calf with nutritious milk means the mother has to eat more nutritious food herself.
Effect on the environment
Elephants can have profound impacts on the ecosystems they occupy, and both positive and negative effects on other species especially with their foraging activities. By pulling down trees to eat leaves, breaking branches, and pulling out roots, they reduce woody cover, creating clearings in forests, converting forests to savannas, and converting savannas to grasslands. These changes tend to benefit grazers at the expense of browsers.
Dung beetles and termites both eat elephant feces. During the dry season, elephants use their tusks to dig into river beds to reach underground sources of water. These holes may then become essential sources of water for other species. Elephants make paths through their environment that are used by other animals. Some of these pathways have apparently been used by several generations of elephants, used by humans and eventually even been converted to roads.
Threats
Hunting
The threat to the African elephant presented by the ivory trade is unique to the species. Larger, long-lived, slow-breeding animals, like the elephant, are more susceptible to overhunting than other animals. They cannot hide, and it takes many years for an elephant to grow and reproduce. An elephant needs an average of 140 kg (300 lb) of vegetation a day to survive. As large predators are hunted, the local small grazer populations (the elephant's food competitors) find themselves on the rise. The increased number of herbivores ravage the local trees, shrubs, and grasses. Elephants themselves have few natural predators besides man and, occasionally, lions. However, many African governments legally allow limited hunting. The large amount of money that is charged for the necessary permits is often used to support conservation efforts, and the small number of permits issued (usually for older animals) ensure that populations are not depleted.[58]
At the turn of the 20th century, it is estimated that elephants numbered between 5 and 10 million, but hunting and habitat destruction had reduced their numbers to 400,000 to 500,000 by the end of the century.[59] In the ten years preceding 1990 the population more than halved from 1.3 million to around 600,000, largely caused by the ivory trade, prompting an international ivory ban.[60][61] While elephant populations are increasing in parts of southern and eastern Africa,[62] other African nations report a decrease of their elephant populations by as much as two-thirds, and populations in even some protected areas are in danger of being eliminated[63] Chad has a decades-old history of poaching of elephants, which has caused the elephant population of the region, which exceeded 300,000 in 1970, to drop to approximately 10,000 today.[64] In Virunga National Park, in eastern Democratic Republic of Congo, the number of elephants living in the observable area of the park fell from 2,889 in 1951 to 348 in 2006.[65]
Habitat loss
Another threat to elephants' survival in general is the ongoing cultivation of their habitats with increasing risk of conflicts of interest with human cohabitants. These conflicts kill 150 elephants and up to 100 people per year in Sri Lanka.[66] The Asian elephants' demise can be attributed mostly to loss of its habitat.
As larger patches of forest disappear, the ecosystem is affected in profound ways. The trees are responsible for anchoring soil and absorbing water runoff. Floods and massive erosion are common results of deforestation. Elephants need massive tracts of land because, much like the slash-and-burn farmers, they are used to crashing through the forest, tearing down trees and shrubs for food and then cycling back later on, when the area has regrown. As forests are reduced to small pockets, elephants become part of the problem, quickly destroying all the vegetation in an area, eliminating all their resources.
National parks
Africa's first official reserve, Kruger National Park, eventually became one of the world's most famous and successful national parks.[67] There are, however, many problems associated with the establishment of these reserves. For example, elephants range through a wide tract of land with little regard for national borders. Once a reserve is established and fences erected, many animals find themselves cut off from their winter feeding grounds or spring breeding areas. Some animals may die as a result, while others, like the elephants, may just trample over the fences, wreaking havoc in nearby fields. When confined to small territories, elephants can inflict an enormous amount of damage to the local landscapes.[68]
Additionally, some reserves, such as Kruger National Park has, in the opinion of wildlife managers, suffered from elephant overcrowding, at the expense of other species of wildlife within the reserve. On 25 February 2008, the South Africa announced that they would reintroduce culling for the first time since 1994 to control elephant numbers although no cull has yet taken place.[69] Nevertheless, as scientists learn more about nature and the environment, it becomes very clear that these parks may be the elephants' last hope against the rapidly changing world around them.
Humans and elephants
Hunting
Elephant hunting, both legal and illegal, has had some unexpected consequences on elephant anatomy as well. African ivory hunters, by killing only tusked elephants, have given a much larger chance of mating to elephants with small tusks or no tusks at all. The propagation of the absent-tusk gene has resulted in the birth of large numbers of tuskless elephants, now approaching 30% in some populations (compare with a rate of about 1% in 1930)[citation needed]. Tusklessness, once a rare genetic abnormality, has become a widespread hereditary trait.
It is possible, if unlikely, that continued selection pressure could bring about a complete absence of tusks in African elephants. The effect of tuskless elephants on the environment, and on the elephants themselves, could be dramatic. Elephants use their tusks to root around in the ground for necessary minerals, tear apart vegetation, and spar with one another for mating rights. Without tusks, elephant behaviour could change dramatically.[70]
Domestication and use
Elephants have been working animals used in various capacities by humans. Seals found in the Indus Valley suggest that the elephant was first domesticated in ancient India. However, elephants have never been truly domesticated: the male elephant in his periodic condition of musth is dangerous and difficult to control. Therefore, elephants used by humans have typically been female, war elephants being an exception; as female elephants in battle will run from a male, only males could be used in war. It is generally more economical to capture wild young elephants and tame them than to breed them in captivity (see also elephant "crushing").
The Laotians have been domesticating elephant for centuries, and about 500 domesticated elephants are still employed, the majority of which work in the Xaignabouli province. These elephants are mainly employed in the logging industry, with ecotourism emerging as a sustainable and environmentally friendly alternative. Elefantasia is a local INGO aiming to reconvert logging elephants into ecotourism practices, thus allowing Asian elephants the ability to supply their mahouts with income while still allowing them to breed.
Elephants are also commonly exhibited in zoos and wild animal parks. About 1200 elephants are kept in western zoos. A study shows that the lifespan of elephants in European zoos is about half as long as those living in protected areas in Africa and Asia.[71] As of July 2010, the oldest living African elephant in captivity is Ruaha (59) at Zoo Basel .[72]
Elephants are revered in India (and are worshipped in ceremonies such as the Aanayoottu).
Warfare
War elephants were used by armies in the Indian subcontinent, the Warring States of China, and later by the Persian Empire. This use was adopted by Hellenistic armies after Alexander the Great experienced their worth against King Porus, notably in the Ptolemaic and Seleucid diadoch empires. The Carthaginian general Hannibal took elephants across the Alps when he was fighting the Romans, but brought too few elephants to be of much military use, although his horse cavalry was quite successful; he probably used a now-extinct third African subspecies, the North African forest elephant, smaller than its two southern cousins, and presumably easier to domesticate. A large elephant in full charge could cause tremendous damage to infantry, and cavalry horses would be afraid of them (see Battle of Hydaspes).
Industry
Throughout Myanmar (Burma), Siam, India, and most of South Asia, elephants were used in the military for heavy labour, especially for uprooting trees and moving logs, and were also commonly used as executioners to crush the condemned underfoot.
Elephants have also been used as mounts for safari-type hunting, especially Indian shikar (mainly on tigers), and as ceremonial mounts for royal and religious occasions, while Asian elephants have been used for transport and entertainment.
Zoo and circuses
There is growing resistance[73] against the capture, confinement, and use of wild elephants. Animal rights advocates allege elephants in zoos and circuses "suffer a life of chronic physical ailments, social deprivation, emotional starvation, and premature death".[74] Zoos argue that standards for treatment of elephants are extremely high and minimum requirements for such things as minimum space requirements, enclosure design, nutrition, reproduction, enrichment and veterinary care are set to ensure the well-being of elephants in captivity. Circuses continue to have a mixed record. Recently, the city of Los Angeles closed an elephant act with Circus Vazquez due to numerous instances of abuse and neglect (April 2008) ,[75] and, according to PETA, 27 elephants owned by Ringling Bros. and Barnum & Bailey Circus have died since 1992.[76]
Elephants have traditionally been a major part of circuses around the world, being intelligent enough to be trained in a variety of acts (see for example P.T. Barnum's Jumbo and John L. Sullivan, the famous "Boxing Elephant"). However, conditions for circus elephants are unnatural (confinement in small pens or cages, restraints on their feet, lack of companionship of other elephants). Perhaps as a result, there are occasional instances of them turning on their keepers or handlers (examples include Black Diamond and "Murderous Mary").
Elephants raised in captivity sometimes show "rocking behavior", a rhythmic and repetitive swaying which is unreported in free-ranging wild elephants. Thought to be symptomatic of stress disorders, and probably made worse by a barren environment,[77] rocking behavior may be a precursor to aggressive behavior in captive elephants.[78][79] This link is to an image of Devi (little princess), a 30-year-old Asian elephant raised in captivity at the San Diego Zoo showing "rocking behavior".
Hybrids
African and Asian elephant species have disjunct distributions, and do not hybridize in the wild. However, in 1978 at Chester Zoo, an Asian elephant cow gave birth to a hybrid calf sired by an African elephant bull. "Motty", the resulting hybrid male calf, had an African elephant's cheeks, ears (large with pointed lobes) and legs (longer and slimmer), but the toenail numbers, (5 for each front foot, 4 hind) and the single trunk finger of an Asian elephant. His wrinkled trunk was like that of an African elephant. His forehead was sloping with one dome and two smaller domes behind it. The body was African in type, but had an Asian-type center hump and an African-type rear hump. The calf died of infection 12 days later.[80] It is preserved as a mounted specimen at the British Natural History Museum, London. There are unconfirmed rumors of three other hybrid elephants born in zoos or circuses; all are said to have been deformed and none survived.[citation needed]
Elephant aggression
Despite its popularity in zoos, and portrayal as gentle giants in fiction, elephants are among the world's most dangerous animals. They can crush and kill any other land animal, even the rhinoceros. They can experience bouts of rage, and engage in actions that have been interpreted as vindictive.[81] In Africa, groups of young teenage elephants attacked human villages after cullings done in the 1970s and 80s.[82][83] In India, male elephants attack villages at night, destroying homes and killing people regularly. In the Indian state of Jharkhand, 300 people were killed by elephants between 2000 and 2004, and in Assam, 239 people were reported killed by elephants between 2001 and 2006.[81]
Musth
Adult male elephants naturally periodically enter the state called musth (Hindi for "madness"), sometimes spelled "must" in English.
Other causes
Local people have reported their belief that some elephants were drunk during their attacks, although there is no confirmed evidence of this. In December 1998, a herd of elephants overran a village in India. Although locals reported that nearby elephants had recently been observed drinking beer which rendered them "unpredictable", officials considered it the least likely explanation for the attack.[84] An attack on another Indian village occurred in October 1999, and again locals believed the reason was drunkenness, but again the theory was not widely accepted.[85] Purportedly drunk elephants raided yet another Indian village again on December 2002, killing six people, which led to the killing of about 200 elephants by locals.[86]
In popular culture
Elephants are ubiquitous in Western popular culture as emblems of the exotic[87] because their unique appearance and size sets them apart from other animals and because, like other African animals such as the giraffe, rhinoceros, and hippopotamus, they are unfamiliar to Western audiences.[88] Popular culture's stock references to elephants rely on this exotic uniqueness.[88] For instance, a "white elephant" is a byword for something expensive, useless and bizarre.[88]
As characters, elephants are relegated largely to children's literature,[87] in which they are generally cast as models of exemplary behaviour,[87] but account for some of this branch of literature's most iconic characters.[87] Many stories tell of isolated young elephants returning to a close-knit community, such as The Elephant’s Child from Rudyard Kipling's Just So Stories (1902), Dumbo (1942) or The Saggy Baggy Elephant (1947).[88] Other elephant heroes given human qualities include Laurent de Brunhoff's anthropomorphic Babar (1935), David McKee's Elmer (1989) and Dr. Seuss's Horton (1940).[88] More than other exotic animals, elephants in fiction are surrogates for humans,[88] with their concern for the community and each other depicted as something to aspire to.[89]
The use of the elephant as a symbol of the Republican Party (United States) began with an 1874 cartoon by Thomas Nast.
