The African bush elephant (Loxodonta africana), also known as the African savanna elephant, is a species of elephant native to sub-Saharan Africa and the largest living terrestrial animal, with fully grown bulls reaching an average shoulder height of and a body mass of ; the largest recorded specimen had a shoulder height of and an estimated body mass of . It is characterised by its long prehensile trunk with two finger-like processes; a concave back; large ears which help reduce body heat; and sturdy tusks that are noticeably curved. Its skin is grey with scanty hairs, and bending cracks which support thermoregulation by retaining water.
The African bush elephant inhabits a variety of habitats such as forests, grasslands, woodlands, wetlands and agricultural land. It is a mixed herbivore feeding mostly on grasses, creepers, herbs, leaves, and bark. The average adult consumes about of vegetation and of water each day. It is a social animal that lives in herds of cows and their offspring. Adult bulls usually live alone or in small bachelor groups. During the mating season, males undergo musth, a period of high testosterone levels and heightened aggression. The menstrual cycle of cows lasts three to four months, and gestation around 22 months, the longest of any mammal.
Since 2021, the African bush elephant 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. 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, though this trend was curtailed by raising penalties for poaching and improving law enforcement. Poaching of the elephant in the 1970–1980s were considered the largest killings in history. In human culture, elephants have been extensively featured in literature, folklore and media, and are most valued for their large tusks.
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 Paul Matschie in 1900. The first was a specimen from the upper Atbara River in northern Ethiopia, and the second a specimen from the Kilwa area in Tanzania. Elephas africanus toxotis, selousi, peeli, cavendishi, orleansi and rothschildi by Richard Lydekker in 1907 who assumed that ear size is a distinguishing character for a race. These specimens were shot in South Africa, Mashonaland in Zimbabwe, Aberdare Mountains and Lake Turkana area in Kenya, Somaliland, and western Sudan, respectively. North African elephant (L. a. pharaohensis) by Paulus Edward Pieris Deraniyagala in 1948 was a specimen from Fayum in Egypt. Today, these names are all considered synonyms.
A genetic study based on mitogenomic analysis revealed that the African and Asian elephant genetically diverged about 7.6 million years ago. Phylogenetic analysis of nuclear DNA from African bush and forest elephants, Asian elephants, the woolly mammoth, and the American mastodon revealed that the African bush elephant and the African forest elephant form a sister group that genetically diverged at least 1.9 million years ago. They are therefore considered distinct species. Gene flow between the two species, however, might have occurred after the split. Some authors have suggested that L. africana evolved from Loxodonta atlantica.
The fossil record for L. africana is sparse. The earliest possible records of the species are from the Shungura Formation around Omo in Ethiopia, which are dated to the Early Pleistocene, around 2.44-2.27 million years ago. Another possible early record is from the Kanjera site in Kenya, dating to the Middle Pleistocene, around 500,000 years ago. Genetic analysis suggests a major population expansion between 500,000 and 100,000 years ago. Records become more common during the Late Pleistocene, following the extinction of the last African Palaeoloxodon elephant species, Palaeoloxodon jolensis.
Description
The African bush elephant has grey skin with scanty hairs. Its large ears cover the whole shoulder, and can grow as large as . 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. The African bush elephant's ears are pointed and triangular shaped. Its occipital plane slopes forward. Its back is shaped markedly concave. Its sturdy tusks are curved out and point forward. Its long trunk or proboscis ends with two finger-like tips.
Size
The African bush elephant is the largest and heaviest living land animal. Under optimal conditions where individuals are capable of reaching full growth potential, fully grown mature males are about tall at the shoulder and weigh on average (with 90% of fully grown males under optimal conditions being between and ). Mature fully grown females are smaller at about tall at the shoulder and in weight on average under optimal growth conditions (with 90% of fully grown females ranging between and in optimal conditions). The largest well-measured bull, shot in Angola in 1974, is calculated to have been tall at the shoulder, with this individual having an estimated weight of . 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.
Dentition The dental formula of the African bush elephant is . They develop six molars in each jaw quadrant that erupt at different ages and differ in size. The first molars grow to a size of wide by long, are worn by the age of one year and lost by the age of about 2.5 years. The second molars start protruding at the age of about six months, and grow to a size of wide by long and are lost by the age of 6–7 years. The third molars protrude at the age of about one year, grow to a size of wide by long, and are lost by the age of 8–10 years. The fourth molars show by the age of 6–7 years, grow to a size of wide by long and are lost by the age of 22–23 years. The dental alveoli of the fifth molars are visible by the age of 10–11 years. They grow to a size of wide by long and are worn by the age of 45–48 years. The dental alveoli of the last molars are visible by the age of 26–28 years. They grow to a size of wide by long and are well worn by the age of 65 years.
Both sexes have large, curved, maxillary incisors known as tusks that continue growing throughout their lives. In the wild, a large percentage of elephants experience a tusk fracture, although this is more prevalent in captivity. A tusk fracture of any sort usually results in serious infections, as the pulp is exposed to the elements. The tusks erupt when they are 1–3 years old. Tusks grow from deciduous teeth known as tushes that develop in the upper jaw and consist of a crown, root and pulpal cavity, which are completely formed soon after birth. Tushes reach a length of . They are composed of dentin and coated with a thin layer of cementum. Their tips bear a conical layer of enamel that is usually worn off when the elephant is five years old. Tusks of bulls grow faster than tusks of cows. Mean weight of tusks at the age of 60 years is in bulls and in cows. The longest known tusk of an African bush elephant measured and weighed .
Distribution and habitat The African bush elephant occurs in sub-Saharan Africa which includes Uganda, Kenya, Tanzania, Botswana, Zimbabwe, Namibia, Zambia, Angola, Malawi, Mali, Rwanda, Mozambique 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.
Populations of African bush elephants are increasing in some areas such as the Kruger National Park, where an annual growth of 4.2% was recorded between 2003 and 2015. There are estimated to be at least 17,000 elephants in the park's vicinity, as of 2015–the most of any area in South Africa. The increase in population occurred after the discontinuation of culling in the mid-1990s.Fulton, William C., "The population growth and control of African elephants in Kruger National Park, South Africa:: Modeling, managing, and ethics concerning a threatened species" (2012). Regis University Student Publications (comprehensive collection). 560. This large elephant population is considered a problem to both the environment and its creatures. As such, with the use of natural processes, conservationists aim to control the ever-growing population. In other places in southern Africa, the elephant population continues to increase. Botswana in particular hosts more African bush elephants than any other country, at 130,000. In a 2019 study, populations were found to be steady, though the authors also noted an unusual increase in carcasses, possibly due to a new wave of poaching which was uncommon at the time.
In East Africa there are roughly 137,000 elephants distributed across six countries in a wide array of habitats, such as grasslands and woodlands. They are most threatened by illegal hunting activities, such as poaching. In one instance, between 2006 and 2013, the population in East Africa fell by 62% due to high poaching pressures. Tanzania (where 80% of the East African population reside) lost the most elephants, while the resident population in Somalia went locally extinct. South Sudan, on the other hand, experienced an increase in elephants. Following successful conservation and governmental actions, Kenya also saw an increase in their elephant numbers. In Ethiopia, the African bush elephant has historically been recorded up to an elevation of . By the late 1970s, the population had declined to one herd in the Dawa River valley and one close to the Kenyan border. As of 2015, there are estimated to be 1,9002,151 elephants in the country, a decrease from 6,00010,000 in the 1970s. It is estimated that between the 1980s and 2010s, elephants in Ethiopia experienced a decline of around 90%hence the endangered assessment.
In West and Central Africa, the population of elephants are threatened, in large part due to habitat loss and fragmentation associated with rapid growth in human populations. Elephants occur in isolated pockets throughout the region and are for the most part decreasing in number.
Behaviour and ecology Social behaviour
The core of elephant society is the family unit, which mostly comprises several adult cows, their daughters, and their prepubertal sons. Iain Douglas-Hamilton, who observed African bush elephants for 4.5 years in Lake Manyara National Park, coined the term 'kinship group' for two or more family units that have close ties. The family unit is led by a matriarch who at times also leads the kinship group. Groups cooperate in locating food and water, in self-defense, and in caring for offspring (termed allomothering). Group size varies seasonally and between locations. In Tsavo East and Tsavo West National Parks, groups are bigger in the rainy season and areas with open vegetation. Aerial surveys in the late 1960s to early 1970s revealed an average group size of 6.3 individuals in Uganda's Rwenzori National Park and 28.8 individuals in Chambura Game Reserve. In both sites, elephants aggregated during the wet season, whereas groups were smaller in the dry season.