African bush elephant
African bush elephant Temporal range:
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A female in Mikumi National Park, Tanzania | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Proboscidea |
Family: | Elephantidae |
Genus: | Loxodonta |
Species: | L. africana[1]
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Binomial name | |
Loxodonta africana[1] (Blumenbach, 1797)
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Subspecies | |
See text | |
Range of the African bush elephant Resident Possibly resident Possibly extinct Resident and reintroduced
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Synonyms | |
Elephas africanus |
The African bush elephant (Loxodonta africana), also known as the African savanna elephant, is one of two extant African elephant species and one of three extant elephant species. It is the largest living terrestrial animal, with bulls reaching an average shoulder height of 3.04–3.36 metres (10.0–11.0 ft) and a body mass of 5.2–6.9 tonnes (11,500–15,200 lb), with the largest recorded specimen having a shoulder height of 3.96 metres (13.0 ft) and a body mass of 10.4 tonnes (22,900 lb).[3]
It is distributed across 37 African countries and inhabits forests, grasslands and woodlands, wetlands and agricultural land. Since 2021, it has been listed as Endangered on the IUCN Red List. It is threatened foremost by habitat destruction, and in parts of its range also by poaching for meat and ivory.[2]
It is a social mammal, travelling in herds composed of cows and their offspring. Adult bulls usually live alone or in small bachelor groups. It is a herbivore, feeding on grasses, creepers, herbs, leaves, and bark. The menstrual cycle lasts three to four months, and females are pregnant for 22 months, the longest gestation period of any mammal.[4]
Taxonomy and evolution
In the 19th and 20th centuries, several zoological specimens were described by naturalists and curators of natural history museums from various parts of Africa, including:
- Elephas (Loxodonta) oxyotis and Elephas (Loxodonta) knochenhaueri by
- Elephas africanus toxotis, selousi, peeli, cavendishi, orleansi and rothschildi by Aberdare Mountains and Lake Turkana area in Kenya, Somaliland, and western Sudan, respectively.[6]
- Fayum in Egypt.[7]
Today, these names are all considered synonyms.[1]
A genetic study based on
The fossil record for L. africana is sparse. The earliest possible records of the species are from the
Description
The African bush elephant has grey skin with scanty hairs. Its large ears cover the whole shoulder,[14] and can grow as large as 2 m × 1.5 m (6 ft 7 in × 4 ft 11 in).[15] Its large ears help to reduce body heat; flapping them creates air currents and exposes large blood vessels on the inner sides to increase heat loss during hot weather.
Size
The African bush elephant is the largest and heaviest land animal. On average, males are about 3.20 m (10.5 ft) tall at the shoulder and weigh 6.0 t (6.6 short tons), while females are smaller at about 2.60 m (8 ft 6 in) tall at the shoulder and 3.0 t (3.3 short tons) in weight.[3][19][20][21] The maximum recorded shoulder height of an adult bull is 3.96 m (13.0 ft), with this individual having an estimated weight of 10.4 t (11.5 short tons).[3] Elephants attain their maximum stature when they complete the fusion of long-bone epiphyses, occurring in males around the age of 40 and females around 25 years of age.[3]
Dentition
The
Both sexes have tusks, which erupt when they are 1–3 years old and grow throughout life. They are composed of
Distribution and habitat
The African bush elephant occurs in sub-Saharan Africa which includes Uganda, Kenya, Tanzania, Botswana, Zimbabwe, Namibia, Zambia, Angola and South Africa. It moves between a variety of habitats, including subtropical and temperate forests, dry and seasonally flooded grasslands, woodlands, wetlands, and agricultural land from sea level to mountain slopes. In Mali and Namibia, it also inhabits desert and semi-desert areas.[2]
In Ethiopia, the African bush elephant has historically been recorded up to an elevation of 2,500 m (8,200 ft). By the late 1970s, the population had declined to a herd in the Dawa River valley and one close to the Kenyan border.[27]
Behavior and ecology
Social behavior
The core of elephant society is the family unit, which mostly comprises several adult cows, their daughters, and their
Young bulls gradually separate from the family unit when they are between 10 and 19 years old. They range alone for some time or form all-male groups.[32] A 2020 study highlighted the importance of old bulls for the navigation and survival of herds and raised concerns over the removal of old bulls as "currently occur[ring] in both legal trophy hunting and illegal poaching".[33]
Temperature regulation
It was first hypothesized that African bush elephants sustain the intense savanna heat by performing heterothermy or matching their internal temperature with the environment.[34] Instead, African bush elephants have curved skin that generates bending cracks, which support thermoregulation by water retention.[35] These bending cracks also contribute to an evaporative cooling process which causes elephants to maintain their body temperature regardless of air temperature via homeothermy. [34]
Diet
The African bush elephant is
Communication
Africa bush elephants use their trunks for tactile communication. When greeting, a lower ranking individual will insert the tip of its trunk into its superior's mouth. Elephants will also stretch out their trunk toward an approaching individual they intend to greet. Mother elephants reassure their young with touches, embraces, and rubbings with the foot while slapping disciplines them. During courtship, a couple will caress and intertwine with their trunks while playing and fighting individuals wrestle with them.[41]
Elephant vocals are variations of rumbles, trumpets, squeals, and screams. Rumbles are mainly produced for long-distance communication and cover a broad range of frequencies which are mostly below what a human can hear. Infrasonic rumbles can travel vast distances and are important for attracting mates and scaring off rivals.[41]
At Amboseli National Park several different infrasonic calls have been identified:[42]
- Greeting rumble – is emitted by adult female members of a family group that have united after having been separated for several hours.
- Contact call – soft, unmodulated sounds made by an individual that has been separated from the group.
- Contact answer – made in response to the contact call; starts out loud, but softens toward the end.
- "Let's go" rumble – a soft rumble emitted by the matriarch to signal to the other herd members that it is time to move to another spot.
- Musth rumble – distinctive, low-frequency pulsated rumble emitted by musth males (nicknamed the "motorcycle").
- Female chorus – a low-frequency, modulated chorus produced by several cows in response to a musth rumble.
- Postcopulatory call – made by an oestrous cow after mating.
- Mating pandemonium – calls of excitement made by a cow's family after she has mated.
Growls are audible rumbles and happen during greetings. When in pain or fear, an elephant makes an open-mouthed growl known as a bellow while a drawn-out growl is a moan. Growling can escalate into a roaring when the elephant is issuing a threat. Trumpeting is made by blowing through the trunk and signals excitement, distress, or aggression. Juvenile elephants squeal in distress while screaming is made by adults for intimidation.[41]
Musth
Bulls in musth experience swelling of the
Young bulls in musth killed about 50
Reproduction
In captivity, cows have anAfrican bush elephants mate during the rainy season.[53] Bulls in musth cover long distances in search of cows and associate with large family units. They listen for the cows' loud, very low frequency calls and attract cows by calling and by leaving trails of strong-smelling urine. Cows search for bulls in musth, listen for their calls, and follow their urine trails.[56] Bulls in musth are more successful at obtaining mating opportunities than those who are not. A cow may move away from bulls that attempt to test her estrous condition. If pursued by several bulls, she will run away. Once she chooses a mating partner, she will stay away from other bulls, which are threatened and chased away by the favoured bull. Competition between bulls overrides their choice sometimes.[54]
Gestation lasts 22 months. The interval between births was estimated at 3.9 to 4.7 years in Hwange National Park.[53] Where hunting pressure on adult elephants was high in the 1970s, cows gave birth once in 2.9 to 3.8 years.[57] Cows in Amboseli National Park gave birth once in 5 years on average.[54]
The birth of a calf was observed in Tsavo East National Park in October 1990. A group of 80 elephants including eight bulls had gathered in the morning in a 150 m (490 ft) radius around the birth site. A small group of calves and cows stood near the pregnant cow, rumbling and flapping their ears. One cow seemed to assist her. While she was in labour, fluid streamed from her temporal and ear canals. She remained standing while giving birth. The newborn calf struggled to its feet within 30 minutes and walked 20 minutes later. The mother expelled the placenta about 100 minutes after birth and covered it with soil immediately.[58]
Captive-born calves weigh between 100 and 120 kg (220 and 260 lb) at birth and gain about 0.5 kg (1.1 lb) weight per day.[59] Cows lactate for about 4.8 years.[60] Calves exclusively suckle their mother's milk during the first three months. Thereafter, they start feeding independently and slowly increase the time spent feeding until they are two years old. During the first three years, male calves spend more time suckling and grow faster than female calves. After this period, cows reject male calves more frequently from nursing than female calves.[61]
The maximum lifespan of the African bush elephant is between 70 and 75 years.[62] Its generation length is 25 years.[63]
Predators
Adult elephants are considered invulnerable to predation.[64] Calves, usually under two years, are sometimes preyed on by lions and spotted hyenas.[18] Adult elephants often chase off predators, especially lions, by mobbing behavior.[65] Juveniles are usually well defended by protective adults though serious drought makes them vulnerable to lion predation.[66]
In Botswana's
Threats
The African bush elephant is threatened primarily by
Poaching
Poachers target foremost elephant bulls for their tusks, which leads to a skewed sex ratio and affects the survival chances of a population. Access of poachers to unregulated black markets is facilitated by corruption and periods of civil war in some elephant range countries.[69]
During the 20th century, the African bush elephant population was decimated.[70] Poaching of the elephant has dated back to the years 1970 and 1980, which were considered the largest killings in history. The species is placed in harm's way due to the limited conservation areas provided in Africa. In most cases, the killings of the African bush elephant have occurred near the outskirts of the protected areas.[2]
Between 2003 and 2015, the illegal killing of 14,606 African bush elephants was reported by rangers across 29 range countries. Chad is a major transit country for smuggling of ivory in West Africa. This trend was curtailed by raising penalties for poaching and improving law enforcement.[71]
In June 2002, a container packed with more than 6.5 t (6.4 long tons; 7.2 short tons)
When the international ivory trade reopened in 2006, the demand and price for ivory increased in Asia. The African bush elephant population in Chad's Zakouma National Park numbered 3,900 individuals in 2005. Within five years, more than 3,200 elephants were killed. The park did not have sufficient guards to combat poaching, and their weapons were outdated. Well-organized networks facilitated smuggling the ivory through Sudan.[73] Poaching also increased in Kenya in those years.[74] In Samburu National Reserve, 41 bulls were illegally killed between 2008 and 2012, equivalent to 31% of the reserve's elephant population.[75]
These killings were linked to confiscations of ivory and increased prices for ivory on the local black market.[76] About 10,370 tusks were confiscated in Singapore, Hong Kong, Taiwan, Philippines, Thailand, Malaysia, Kenya and Uganda between 2007 and 2013. Genetic analysis of tusk samples showed that they originated from African bush elephants killed in Tanzania, Mozambique, Zambia, Kenya, and Uganda. Most of the ivory was smuggled through East African countries.[77]
In addition to elephants being poached, their carcasses may be poisoned by the poachers to avoid detection by vultures, which help rangers detect poaching activity by circling dead animals. This poses a threat to those vultures or birds that scavenge the carcasses. On 20 June 2019, the carcasses of two tawny eagles and 537 endangered Old World vultures including 468 white-backed vultures, 17 white-headed vultures, 28 hooded vultures, 14 lappet-faced vultures and 10 Cape vultures found dead in northern Botswana were suspected to have died after eating the poisoned carcasses of three elephants.[78][79][80][81]
Intensive poaching leads to strong selection on tusk attributes; African elephants in areas with heavy poaching often have smaller tusks and a higher frequency of
Habitat changes
Vast areas in Sub-Saharan Africa were transformed for agricultural use and the building of infrastructure. This disturbance leaves the elephants without a stable habitat and limits their ability to roam freely. Large corporations associated with
Pathogens
Observations at Etosha National Park indicate that African bush elephants die due to anthrax foremost in November at the end of the dry season.[86] Anthrax spores spread through the intestinal tracts of vultures, jackals and hyaenas that feed on the carcasses. Anthrax killed over 100 elephants in Botswana in 2019.[87]
It is thought that wild bush elephants can contract fatal tuberculosis from humans.[88] Infection of the vital organs by Citrobacter freundii bacteria caused the death of an otherwise healthy bush elephant after capture and translocation.[85]
From April to June 2020, over 400 bush elephants died in Botswana's Okavango Delta region after drinking from desiccating waterholes that were infested with cyanobacteria.[89] Neurotoxins produced by the cyanobacteria caused calves and adult elephants to wander around confused, emaciated and in distress. The elephants collapsed when the toxin impaired their motor functions and their legs became paralysed. Poaching, intentional poisoning, and anthrax were excluded as potential causes.[90]
Conservation
Both African elephant species have been listed on
In 1986, the African Elephant Database was initiated to collate and update information on the distribution and status of elephant populations in Africa. The database includes results from aerial surveys, dung counts, interviews with local people, and data on poaching.[71]
Researchers discovered that playing back the recorded sounds of
Status
In 2008, the IUCN Red List assessed the African elephant (then considered as a single species) as vulnerable. Since 2021, the African bush elephant has individually been assessed Endangered, after the global population was found to have decreased by more than 50% over 3 generations.[92] About 70% of its range is located outside protected areas.[2]
In 2016, the global population was estimated at 415,428 ± 20,111 individuals distributed in a total area of 20,731,202 km2 (8,004,362 sq mi), of which 30% is protected. Approximately 42% of the total population lives in nine southern African countries comprising 293,447 ± 16,682 individuals; Africa's largest population lives in Botswana with 131,626 ± 12,508 individuals.[71]
In captivity
The social behavior of elephants in captivity mimics that of those in the wild. Cows are kept with other cows, in groups, while bulls 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 bull interaction. Elsewhere, bulls were only allowed to smell each other. Bulls and cows were allowed to interact for specific purposes such as breeding. In that event, cows were more often moved to the bull than the bull to the cow. Cows are more often kept in captivity because they are easier and less expensive to house.[93]
See also
- 2006 Zakouma elephant slaughter
- Dwarf elephant
- Elephant cognition
- Knysna elephants
- Largest organisms
- List of individual elephants
- Pygmy elephant
Notes
- ^ The populations of Botswana, Namibia, South Africa, and Zimbabwe are listed in Appendix II for specific purposes.
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Further reading
- Caitlin O'Connell (2015). Elephant Don: The Politics of a Pachyderm Posse. University of Chicago Press. ISBN 978-0226106113.
External links
- Elephant Information Repository Archived 18 March 2009 at the Wayback Machine – An in-depth resource on elephants
- "African Bush Elephant Loxodonta africana (Blumenbach 1797)" at the Encyclopedia of Life
- ARKive – images and movies of the African Bush Elephant (Loxodonta africana)
- BBC Wildlife Finder – Clips from the BBC archive, news stories and sound files of the African Bush Elephant
- View the elephant genome on Ensembl
- People Not Poaching: The Communities and IWT Learning Platform
- Handwerk, B. (2006). "African Elephants Slaughtered in Herds Near Chad Wildlife Park". National Geographic. Archived from the original on 1 September 2006. Retrieved 1 September 2006.