|African bush elephant, Loxodonta africana in Mikumi National Park, Tanzania|
|Distribution of Loxodonta (2007)|
African elephants are elephants of the genus Loxodonta (from the Greek words loxo (oblique sided) and donta (tooth))). The genus consists of two extant species: the African bush elephant and the smaller African forest elephant. Loxodonta is one of two existing genera of the family, Elephantidae. Fossil remains of Loxodonta have been found only in Africa, in strata as old as the middle Pliocene.
One species of African elephant, the bush elephant, is the largest living terrestrial animal, while the forest elephant is the third largest. Their thickset bodies rest on stocky legs, and they have concave backs. Their large ears enable heat loss. The upper lip and nose form a trunk. The trunk acts as a fifth limb, a sound amplifier, and an important method of touch. African elephants' trunks end in two opposing lips, whereas the Asian elephant trunk ends in a single lip. In L. africana, males stand 3.2–4.0 m (10–13 ft) tall at the shoulder and weigh 4,700–6,048 kg (10,360–13,330 lb), while females stand 2.2–2.6 m (7–9 ft) tall and weigh 2,160–3,232 kg (4,762–7,125 lb); L. cyclotis is smaller with male shoulder heights of up to 2.5 m (8 ft). The largest recorded individual stood four metres (13.1 ft) at the shoulders and weighed 10 tonnes (10 long tons; 11 short tons).
Elephants have four molars; each weighs about 5 kg (11 lb) and measures about 30 cm (12 in) long. As the front pair wears down and drops out in pieces, the back pair moves forward, and two new molars emerge in the back of the mouth. Elephants replace their teeth four to six times in their lifetime. At about 40 to 60 years of age, the elephant no longer has teeth and will likely die of starvation, a common cause of death. The enamel plates of the molars are fewer in number than in Asian elephants.
The elephants' tusks are firm teeth; the second set of incisors become the tusks. They are used for digging for roots and stripping the bark from trees for food; for fighting each other during mating season; and for defending themselves against predators. The tusks weigh from 23–45 kg (51–99 lb) and can be from 1.5–2.4 m (5–8 ft) long. Unlike Asian elephants, both male and female African elephants have tusks. They are curved forward and continue to grow throughout the elephant's lifetime.
Distribution and habitat
In 1825, Georges Cuvier named the genus, "Loxodonte". An anonymous author romanized the spelling to "Loxodonta", and the International Code of Zoological Nomenclature (ICZN) recognizes this as the proper authority.
- * African bush elephant, Loxodonta africana
- * African forest elephant, Loxodonta cyclotis
- * Loxodonta atlantica (fossil). Presumed ancestor of the modern African elephants
- * Loxodonta exoptata (fossil). Presumed ancestor of L. atlantica
- * ? Loxodonta adaurora (fossil) May belong in Mammuthus.
Bush and forest elephants were formerly considered subspecies of Loxodonta africana. As described in the entry for the forest elephant in the third edition of Mammal Species of the World (MSW3), there is morphological and genetic evidence that they should be considered as separate species.
Much of the evidence cited in MSW3 is morphological. The African forest elephant has a longer and narrower mandible, rounder ears, a different number of toenails, straighter and downward tusks, and considerably smaller size. With regard to the number of toenails: the African bush elephant normally has four toenails on the front foot and three on the hind feet, the African forest elephant normally has five toenails on the front foot and four on the hind foot (like the Asian elephant), but hybrids between the two species commonly occur.
MSW3 lists the two forms as full species and does not list any subspecies in its entry for Loxodonta africana. However, this approach is not taken by the United Nations Environment Programme's World Conservation Monitoring Centre nor by the International Union for Conservation of Nature (IUCN), both of which list L. cyclotis as a synonym (not even a subspecies) of L. africana. A consequence of the IUCN taking this view is that the IUCN Red List makes no independent assessment of the conservation status of the two forms of African elephant. It merely assesses the two forms taken together, as vulnerable.
A study of nuclear DNA sequences, published in 2010, indicated that the divergence date between forest and savanna elephants was 2.6 – 5.6 million years ago, similar to the divergence date estimated for the Asian elephant and the woolly mammoths (2.5 – 5.4 million years ago), which strongly supports their status as separate species. Forest elephants were found to have a high degree of genetic diversity, perhaps reflecting periodic fragmentation of their habitat during the climatic changes of the Pleistocene.
African elephant societies are arranged around family units. Each family unit is made up of around ten closely related females and their calves and is led by an older female known as the matriarch. When separate family units bond, they form kinship or bond groups. After puberty, male elephants tend to form alliances with other males.
Elephants are at their most fertile between the ages of 25 and 45. Calves are born after a gestation period of nearly two years. The calves are cared for by their mother and other young females in the group, known as allomothers.
African elephants may eat up to 450 kilograms (992 lb) of vegetation per day, although their digestive system is not very efficient; only 40 percent of this food is properly digested. They use their trunk to pluck at leaves and their tusks to tear at branches, which can cause enormous damage to folliage.
African elephants are highly intelligent, and they have a very large and highly convoluted neocortex, a trait they share with humans, apes and some dolphin species. They are amongst the world's most intelligent species. With a mass of just over 5 kg (11 lb), elephant brains are larger than those of any other land animal, and although the largest whales have body masses twenty-fold those of a typical elephant, whale brains are barely twice the mass of an elephant's brain. The elephant's brain is similar to that of humans in terms of structure and complexity. For example, the elephant's cortex has as many neurons as that of a human brain, suggesting convergent evolution.
Elephants exhibit a wide variety of behaviors, including those associated with grief, learning, allomothering, mimicry, art, play, a sense of humor, altruism, use of tools, compassion, cooperation, self-awareness, memory and possibly language. All point to a highly intelligent species that is thought to be equal with cetaceans, and primates.
African elephants show sexual dimorphism in weight and shoulder height by age 20, due to the rapid early growth of males; by age 25, males are double the weight of females. However, both sexes continue to grow throughout their lives.
Female African elephants are able to start reproducing at around 10 to 12 years of age, and are in estrus for about 2 to 7 days. They do not mate at a specific time; however, they are less likely to reproduce in times of drought than when water is plentiful. The gestation period of an elephant is 22 months and fertile females usually give birth every 3 – 6 years, so if they live to around 50 years of age, they may produce 7 offspring. Females are a scarce and mobile resource for the males so there is intense competition to gain access to estrous females.
After growing up, males begin to experience musth, a physical and behavioral condition that is characterized by elevated testosterone, aggression and more sexual activity. Musth also serves a purpose of calling attention to the females that they are of good quality, and it cannot be mimicked as certain calls or noises may be (elephantconversation.org). Males sire few offspring in periods when they are not in musth. During the middle of estrus, female elephants look for males in musth to guard them. The females will yell, in a loud, low way to attract males from far away. Male elephants can also smell the hormones of a female ready for breeding. This leads males to compete with each other to mate, which results in the females mating with older, healthier males. Females choose to a point who they mate with, since they are the ones who try to get males to compete to guard them. However, females are not guarded in the early and late stages of estrus, which may permit mating by younger males not in musth.
Males over the age of 25 compete strongly for females in estrous, and are more successful the larger and more aggressive they are. Bigger males tend to sire bigger offspring. Wild males begin breeding in their thirties when they are at a size and weight that is competitive with other adult males. Male reproductive success is maximal in mid-adulthood and then begins to decline. However, this can depend on the ranking of the male within their group, as higher-ranking males maintain a higher rate of reproduction. Most observed matings are by males in musth over 35 years of age. Twenty-two long observations showed that age and musth are extremely important factors; “… older males had markedly elevated paternity success compared with younger males, suggesting the possibility of sexual selection for longevity in this species.” (Hollister-Smith, et al. 287).
Males usually only stay with a female and her herd for a few weeks before moving on in search for another mate. Less than a third of the population of female elephants will be in estrus at any given time and gestation period of an elephant is long, so it makes more evolutionary sense for a male to search for as many females as possible rather than stay with one group.
Mating in captivity
The social behavior of elephants in captivity mimics that of those in the wild. Females are kept with other females, in groups, while males tend to be separated from their mothers at a young age, and are kept apart. According to Schulte, in the 1990s, in North America, a few facilities allowed male interaction. Elsewhere, males were only allowed to smell each other. Males and females were allowed to interact for specific purposes such as breeding. In that event, females were more often moved to the male than the male to the female. Females are more often kept in captivity because they are easier and less expensive to house.
Population estimates and poaching
During the 20th century, poaching significantly reduced the population of Loxodonta in some regions. The World Wildlife Foundation believes there were between 3 and 5 million African elephants as recently as the 1930s and 1940s. Between 1980 and 1990, when an international ban on ivory trade came into force, the population of African elephants was more than halved from 1.3 million to around 600,000. In Chad, for example, the population declined from 400,000 in 1970 to about 10,000 in 2006.
The magnitude of poaching during 2006-2012 has been large, including some 3,000 elephants slaughtered in three years from 2006 through 2009. In an incident lasting a few days in February 2012 in Bouba N'Djida park in Cameroon, 650 elephants were poached. In Chad in early March 2013, 86 elephants, including 33 pregnant females were killed in "a potentially devastating blow to one of central Africa's last remaining elephant populations." Between 1973 and 1989, the African elephant population of Kenya declined by eighty-five percent.
According to the World Wildlife Foundation the population of African elephants in Southern Africa is large and expanding with an estimated 300,000 now roaming the region. Overall, the total population of African elephants is estimated to be around 700,000 compared to the Asian elephant population of 32,000. Large populations of elephants are confined to well-protected areas. However, less than 20% of the African elephant range is under formal protection.
Legal protections and conservation status
Protection of African elephants is a high profile conservation cause in many countries. In 1989, the Kenyan Wildlife Service burnt a stockpile of tusks in protest against the ivory trade. However, African elephant populations can be devastated by poaching despite nominal governmental protection, and some nations permit the hunting of elephants for sport. In 2012, The New York Times reported a large upsurge in ivory poaching, with about 70% of the product flowing to China.
Conflicts between elephants and a growing human population are a major issue in elephant conservation. Human encroachment into natural areas where bush elephants occur or their increasing presence in adjacent areas has spurred research into methods of safely driving groups of elephants away from humans. Playback of the recorded sounds of angry honey bees has been found to be remarkably effective at prompting elephants to flee an area. The International Union for Conservation of Nature (IUCN) African elephant specialist group has set up a human-elephant conflict working group. They believe that different approaches are needed in different countries and regions, and so develop conservation strategies at national and regional levels.
Under the auspices of the Convention on Migratory Species of Wild Animals (CMS), also known as the Bonn Convention, a Memorandum of Understanding concerning Conservation Measures for the West African Populations of the African Elephant came into effect on 22 November 2005. The MoU aims to protect the West African elephant population by providing an international framework for state governments, scientists and conservation groups to collaborate in the conservation of the species and its habitat.
This article incorporates text from the ARKive fact-file "African elephant" under the Creative Commons Attribution-ShareAlike 3.0 Unported License and the GFDL.
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|Wikimedia Commons has media related to African elephant.|
- African elephant media at ARKive
- CMS West African Elephant Memorandum of Understanding
- Elephant Information Repository - An in-depth resource on elephants
- "Elephant caves" of Mt Elgon National Park
- ElephantVoices - Resource on elephant vocal communications
- Amboseli Trust for Elephants - Interactive web site
- David Quammen: " Family ties - The elephants of Samburu" National Geographic Magazine September 2008 link
- EIA 25 yrs investigating the ivory trade, reports etc
- EIA (in the USA) reports etc
- International Elephant Foundation