Forest elephant

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Forest elephant
Forest elephant (Loxodonta cyclotis) - cow with calf -

Forest elephant ( Loxodonta cyclotis )
- cow with calf -

Systematics
without rank: Paenungulata
without rank: Tethytheria
Order : Russell animals (Proboscidea)
Family : Elephants (Elephantidae)
Genre : African elephants ( Loxodonta )
Type : Forest elephant
Scientific name
Loxodonta cyclotis
( Matschie , 1900)

The forest elephant ( Loxodonta cyclotis ), sometimes also an African forest elephant , is a species from the genus of the African elephant ( Loxodonta ). The range includes the tropical rainforests of the central and western parts of Africa . It is the smaller of the two representatives of the elephant family on the continent. Outwardly, it is largely similar to its larger relative, the African elephant , but has some deviations in detail. These include the more rounded ears, the clearly straight tusks and the less dented back. The behavior of the two types also corresponds in many areas. The animals live in social groups consisting of closely related cows and their offspring. The bulls, on the other hand, act as loners. In contrast to the African elephant, the herd groups are smaller and less stable. Forest clearings, which form important social contact points for different groups of forest elephants, are of great importance. The diet is largely based on soft plant foods. A large part of the day's workload is spent looking for food. Reproduction takes place all year round, but has a climax in the dry seasons. The offspring usually consists of a calf that is suckled for up to five years.

The first scientific description of the forest elephant took place in 1900. In the second half of the 20th century, the representative elephant was considered a subspecies of the African elephant. Only various anatomical and molecular-genetic studies in the transition to the 21st century led to a discussion of the independent species character of the forest elephant. The problem here is a more or less wide corridor along the northern limit of distribution, in which hybridization with the African elephant occurs. At the beginning of the 20th century, another small elephant form from central Africa was described and called "pygmy elephant". Various studies also show that the "dwarf elephant" is identical to the forest elephant. The stocks have dwindled due to poaching and the destruction of the rainforests; the international commercial trade in the animals is prohibited by the agreements in the Washington Convention on the Protection of Species .

features

Habitus

The forest elephant is smaller than the African elephant ( Loxodonta africana ). The shoulder height of males varies from 214 to 290 cm (average 244 cm), in females it is between 176 and 234 cm (average 198 cm). Studies on animals in the Dzanga Conservation Area in the Central African Republic showed a maximum height of 280 cm. In contrast, animals from the Loango National Park in Gabon were significantly smaller with a maximum of 216 cm. The weight is little known, but it may vary between 2 and 4 tons. Other authors give an average of around 1.7 t.

Outwardly, the forest elephant resembles its larger African relative, but it is more compact and its back line is rather straight and not so clearly indented. The ears are mostly rounder and smaller than the African elephant, but the shape is individually different. The lower edges of the ears can reach below the chin line. The skin color generally appears gray; as a result of mud baths, however, it often tends to be yellowish to reddish brown. The body hair is sparse, with the exception of newborns with thicker black fur. In some females, a slight beard grows on the chin. The tail length differs in individual individuals. The tail can only take up about half the height of the back or touch the ground with the tip. It is wrapped in a thick skin and ends in an asymmetrical, broad tip, which in turn is covered by a tassel made of 2 to 20 cm long hair. As with all elephants, the hands and feet are each five-pointed. In contrast to the African elephant, there are five nail-like structures on the front foot and four on the rear foot.

Skull and dentition features

Comparison of the skulls of the African elephant (left) and the forest elephant (right)

The skull reaches a length of 47 to 63 cm. Like that of the African elephant, it is solidly built, but appears overall wider both on the roof of the skull and on the alveoli of the tusks . A striking feature of the elephant skull are the air-filled chambers of the frontal bone , which have a construction reminiscent of honeycombs. In the forest elephant, the chambers are not as clearly developed as in the African elephant. The lower jaw is long and low in shape. Compared to the African elephant, the symphysis is absolutely and relatively longer with an average length of 18.5 cm. The dentition is typical of mountain out 26 teeth with the following dental formula : . The characteristic tusks are formed from the second upper incisor . They are long and slender, in males they have a basal diameter of 7.0 to 15.5 cm, in female individuals they are significantly slimmer at 5.7 to 8.3 cm. Compared to the African elephant, they are overall more graceful, and their course is noticeably straight, while in the former they are curved. The ivory is harder and more pink in color. An examined animal from Dzanga had tusks up to 180 cm long. The molars have lower crowns than the African elephant. There are typically three milk premolars and three molars . As in all elephants, there are no permanent premolars. The premolars are similar to the molars, so they are clearly molarized. The molars are made up of several folds of enamel (sometimes referred to as lamellodont ) that are connected by dental cement . Teeth change horizontally rather than vertically as in most other mammals.

distribution

Distribution area of ​​the forest elephant in Central Africa, the occurrence in West Africa is not shown

The distribution of the forest elephant is little studied. It is generally found in Central Africa and inhabits the Congo Basin from Equatorial Guinea and Gabon in the west via the Republic of Congo , southern Cameroon and the Central African Republic to the east of the Democratic Republic of the Congo . The species is also present in West Africa . The borders here and in the north of Central Africa are unknown, as there is a more or less wide intermingling corridor with the African elephant and the two elephant representatives partially hybridize there. The habitat consists mainly of intact and dense tropical rainforests , but the forest elephant also partially inhabits the transition zones to the savannah areas . Due to the destruction of the rainforests, the distribution area is largely split up. In western Africa the occurrence of the species is limited to about three dozen isolated forest fragments averaging 800 km² in size. As a rule, the animals use undisturbed forests and avoid areas with intense human activity. Various agricultural areas such as plantations are also rarely visited. Little information is available about the population density ; as a rule, it is determined by counting dung heaps , subordinate to the counting of individuals in areas or by the sounds of the animals. For Gabon the total population is possibly around 25,000 individuals, for the Democratic Republic of the Congo at least 20,000, and for Equatorial Guinea estimates are around 1,300 animals. During a 20-year study in the approximately 6,800 km² Dzanga reserve, more than 3100 animals were observed with a stable annual number of 1660 to 1860 individuals. In the Loango National Park in Gabon, the population density is around 2.57 animals per square kilometer. In contrast, two forest fragments in Ghana housed around 0.04 and 0.64 individuals per square kilometer. In general, several populations in western Africa are considered to be difficult to survive due to their small size and the unequal gender and age distribution.

Way of life

Territorial behavior

Forest elephant at the water bath
Male forest elephants in competition
Forest clearings as important social gathering points

Much information about the way of life of the forest elephant comes from animals in the Dzanga sanctuary , where studies were initiated in 1990. The forest elephant, like the African elephant, is a social animal. The herd, consisting of various related cows and their young animals, forms the basic unit. On average, a herd comprises three individuals. In the area of ​​clearings, which represent important social contact points, larger herds of 20 to 100 animals can also join together. However, they disintegrate again relatively quickly. This social system, known as “separating and merging” ( fission-fusion ), is also found in the African elephant in the open savannah landscapes . In contrast to this, the associations of the forest elephant are smaller and less stable, which is related to the lower distribution of potential predators in the dense forests. The size of the family groups can vary depending on the habitat . In the Odzala National Park in the Republic of the Congo, for example, herds with fewer individuals on average than in more open landscapes were observed at mineral leaks. Also different from the African elephant, the bulls of the forest elephant rarely form bachelor groups, but younger males sometimes come together in loose communities. It is especially in the clearings that cops fight their social competitions and fights for dominance. There are also individual animals of both sexes and almost all age groups.

In principle, the forest elephant is active during the day, it rests about four hours a day. A shorter rest phase takes place during the day, a longer one at night. According to observations in the Dzanga Conservation Area, the greatest activities unfold between 12 noon and 9 p.m. Certain nocturnal activities can also be assumed on the basis of call records. The main daily rhythm consists of foraging for food and moving to the various activity zones. Individual animals overcome up to 25 km within 48 hours, but overall the migration movements are not as long-lasting as with the African elephant. During its hikes, the forest elephant creates paths that extend over several kilometers and connect the individual activity points. Well-trodden paths can be over 1 m wide. The individual herds and individuals use action spaces which, according to various sources, cover an area of ​​500 km² and more. A cow in the Dzanga conservation area used an area of ​​around 880 km² with a maximum distance of 60 km to each other over a period of several weeks. According to investigations in the Loango National Park, the size of the individual territories varies between 11 and 105 km², which is the smallest action space of all elephant representatives to date. A greater overlap at the borders, as is known with the African elephant, was not found here. In contrast, the average size of the action spaces in the Wonga Wongué Presidential Reserve in Gabon based on more than a dozen examined individuals is around 713 km². The size of the male animals with a good 965 km² is almost three times as large as that of the female with 354 km², but the size of the core areas hardly differs between the sexes. In the mosaic landscape of tropical rainforests and open grasslands that dominates here, the animals change daily between the individual types of vegetation. As a result, they cover about 7 to 8 km within 24 hours, which corresponds to an annual migration of 2840 km. In relation to the year they spend two thirds of their time in the tropical rainforests, which they use more often than the open grass areas. The forests are mainly visited during the day during the time of intense sunlight, for this reason the animals usually choose areas with a high density of trees and scrub. A more frequent stay in forest areas could also be determined for the long dry season. However, the forest elephant prefers the grasslands, especially during the short rainy season, and benefits from the renewal of the vegetation cover during this time.

Communication with one another takes place via different vocalizations. The forest elephant, like the other elephants, has excellent hearing and is able to emit and perceive low-frequency tones up to 5 Hz . This is primarily the social rumble, which is by far the most common utterance of the forest elephant. It is particularly useful for communicating with one another, locating herd members and coordinating the joint migration. Noises in the low-frequency range also support communication over long distances. They are often emitted by animals in clearings in the forest in connection with sounds that can be heard by humans. The sounds in the higher frequency range include, in addition to the familiar trumpet, barking, roaring or screaming. In the combination of the higher- and lower-frequency sounds, the forest elephant differs a little from the other elephants, since, in contrast to these, it does not show any preference for higher / lower-frequency over lower / higher-frequency acoustic signals. It is not known whether this is related to the rather closed forest landscapes in the area of ​​distribution of the forest elephant or results from social life. Most of the combined sounds are emitted at night.

Diet

Forest elephants in a clearing dig for mineral-rich soils

The forest elephant feeds on a variety of different plant parts. This includes leaves , fruits and bark . Grasses , which mostly only occur in clearings in the forests, are occasionally also eaten by the animals, but they only make up a small portion of the food. Studies in western Ghana show that the forest elephant feeds on almost 140 different plant species, of which lianas predominate. Fruits are also very common, including the sapote , linden , mulberry and arrowroot plants . There is, however, a regional difference between the dry and rainy seasons, as in Central Africa the proportion of fruit in the former is decreasing in favor of bark and leaves. In West Africa, on the other hand, fruits are more readily available during the dry season. Here the forest elephant moves to freshly harvested arable land in times of low fruit. The animals often eat larger fruits with a diameter of 5 to 18 cm; smaller ones usually only ingest them as “bycatch” when eating leaves.

Trees, less often bushes, serve as food plants. Preferred feeding places are found in clearings and forest edges, which are mainly used when looking for leaves. It is possible that the forest elephant keeps the clearings open because of its regular return. In contrast, the animals consume more fruit and bark in the forests. For the latter, they tend to seek primary forests due to the greater abundance of fruits. As a rule, they eat twig ends or strip off leaves. The breaking of branches or knocking over trees, as is common with the African elephant, has only rarely been observed in the forest elephant. Foraging for food is sometimes very selective, as bark, for example, is only eaten by a few trees.

In addition, mineral leaks and salt brines in forest clearings play an important role, and the forest elephant with its columnar legs sometimes digs holes up to 4 m in diameter in search of mineral-rich water. He may spend several hours a day absorbing these additional nutrients. Among other things, they help the animals to neutralize the sometimes toxic components contained in the plants .

Reproduction

Forest elephant family group

Female animals reach sexual maturity at around 12 to 14 years of age. Something similar is assumed for the young bulls, but their reproductive activities begin later. The rut of the females continues throughout the year, but reaches its peak during the two dry seasons from December to March and July to August. The cycle takes several days. Likewise, during this time it is mainly the largest male individuals who enter the musth , which is associated with secretions from the temporal glands and a constant drop of urine . As a result, the animals have a penetrating smell. In contrast to the African elephant, bulls of the forest elephant do not undertake extensive hikes in the Musth in search of cows willing to mate. Rather, certain local resources such as mineral licks in forest clearings enable a dominant male animal to meet a cow in heat. He then accompanies her and allows her access. The sexual act also takes place, after which the bull separates from the cow and scouts out a new mating opportunity. Only less assertive bulls go on longer journeys.

The gestation period is probably around 660 days, similar to that of the African elephant. According to observations in the Dzanga Sanctuary, a single newborn is usually born. This is immediately able to walk and is in close contact with the mother and other herd members. Standing, the newborn reaches about half the length of the mother's leg. After about a year it can still run under the mother's body; only after about four years is it about half the size of a fully grown animal. The tusks break through when they are around one and a half years old; they are already significantly thicker in male young animals than in female ones. The mother suckles the young animal for up to five years. Then the behavior of the young animals begins to differ according to sex. Female kittens take care of younger calves, males gather and begin to play playful fights. The female offspring usually remain in the herd from the age of eight to ten, while the male becomes independent. At around 25 years of age, the animals are fully grown, but then they still appear relatively slender because the body only fills up over time. The chance of survival for newborns is 97%. From the age of around thirteen, it drops significantly in males compared to females. Man's hunt for tusks may play an important role here. Natural life expectancy is around 50 to 60 years.

Female animals are able to reproduce well into old age. The oldest cow with offspring in the Dzanga sanctuary was estimated to be 59 years old, and the youngest pregnant animal was ten years old. The greatest productivity is achieved by cows between 25 and 39 years of age. The interval between two births is around five years, which is on average a little longer than that of the African elephant. With increasing age, the interval between births also increases, so that it is 14 months longer for older cows. The generation length is assumed to be around 31 years.

Predators, parasites and ecological importance

The forest elephant hardly has any natural enemies. Occasionally the leopard kills a newborn calf. In general, the mortality rate of the young animals is rather low at 3%. Animals over two years can survive alone or orphaned. Little information is available about parasites . From the Kotresten of forest elephants flukes as were Protofasciola or Bivitellobilharzia and roundworms, such Mammomonagamus , Quilonia , Decrusia and Murshidia isolated. In addition, ciliates , including triplumaria , and prototapirella as well as two-winged birds , according to Cobboldia , appear as internal parasites. In contrast to the African elephant, there is hardly any evidence of anthrax disease in forest elephants.

Like the other elephant species, the forest elephant also plays an important role in the ecological network. The animals have an important function as disseminators of seeds from a large number of trees in their habitat. In western Africa alone, the forest elephant transports the seeds of almost 70 species over a distance of 5 to 12 km through its excrement . According to calculations, a single animal distributes around 350 seeds daily over an area of ​​over one square kilometer in this way. According to detailed analyzes in Ghana, only a few plants are directly dependent on the forest elephant for germination and the like. However, some plants, such as members of the Balanites and Panda genera , benefit relatively significantly. The debarking or bending of trees and thus the opening of closed forest landscapes also lead indirectly to the settlement of pioneer plants .

Systematics

General

Internal systematics of today's elephants according to Meyer et al. 2017
 Elephantidae  
  Loxodonta  

 Loxodonta africana


   

 Loxodonta cyclotis



   

 Elephas



Template: Klade / Maintenance / Style

The forest elephant is a species from the genus of the African elephant ( Loxodonta ). Within the genus, the African elephant ( Loxodonta africana ) is also listed as a further representative. The genus Loxodonta forms the sister group of the genus Elephas with the Asian elephant ( Elephas maximus ) as the only member. Both genres are within the family of elephants (Elephantidae) and the order of mammoths (Proboscidea). The trunk animals represent a very old group of originally African animals, whose origins go back around 60 million years. They were once very diverse with adaptations to numerous biotopes and climatic regions. The proboscis colonized large parts of Eurasia and America . Compared to the long tribal history of the proboscis, the elephants are to be regarded as a relatively young line of development, which first formed in the late Miocene . Precursors of today's representatives can be found in fossil form around 7 million years ago. In line with this, the African and Asian elephants separated, according to molecular genetic studies, 7.6 million years ago. The lines of the two current members of the African elephants differentiated themselves from 5.6 to 2.6 million years ago.

Paul Matschie

No subspecies are distinguished within the species. However, the populations of western and central Africa are clearly differentiated in their mitochondrial DNA , for which the arid landscapes of the Dahomey Gap may be responsible. Their separation from one another dates back to the Middle Pleistocene around 609,000 to 463,000 years ago. Some scientists therefore advocate a separation of the two groups on the subspecies or species level. The corresponding results when examining the nuclear DNA are less clear. It is possible that the migrations of individual bulls mask the genetic findings.

The first scientific description goes back to Paul Matschie from 1900. It is based on a male animal that was kept at the Berlin Zoo at the time of the description. Originally it came from Yaoundé in southern Cameroon , the type locality of the species. Matschie led the forest elephant under the name Elephas cyclotis , but at the same time suggested the subspecies name Elephas capensis cyclotis . The epithet he chose because of the design of the ears and managed it from the Greek words κύκλος ( kyklos ) for "circle" and οὖς ( ous ab) for "ear", which means something like "rundohrig". The common name "round-eared elephant", mainly used in older German-language literature, also refers to this .

Classification as Art

From the first description of the forest elephant it is not clear whether the new form should be classified at species or subspecies level. Some authors like Glover M. Allen listed it as an independent species in the 1930s. In a study from 1958, Dieter Backhaus identified the forest elephant as a special form of the African elephant, so that both belonged to one species. Backhaus came to the conclusion after examining animals from the Garamba National Park in the northeast of what is now the Democratic Republic of the Congo , which showed numerous mixed characteristics of both elephant forms (the population there is now considered a hybrid form). Subsequent authors increasingly adopted this opinion in the second half of the 20th century. However, at the turn of the 20th to the 21st century, individual scientists again spoke out against the union of the two elephant representatives and justified this with deviations in body and skull structure. A first DNA analysis from 1999 then revealed a large genetic gap between the forest and African elephants. In the opinion of the authors, the forest elephant should therefore be given an independent species status. Further molecular genetic studies could confirm the previous results. A genetic distance between the two African elephant forms could be determined, which is around 58% of the distance between the genera Loxodonta and Elephas . Including fossil DNA material, it was then shown that the forest elephant is possibly closer to the extinct European forest elephant ( Palaeoloxodon antiquus ) than the African elephant (the term "European forest elephant", however, is not based on an assumed closer relationship to the African forest elephant, but on its predominant occurrence in the wooded warm periods of the Pleistocene ). The fossil form shows a particularly close relationship to the western population of the forest elephant. However, similarities with the African elephant could also be demonstrated, which is attributed to a greater mixing of the individual forms during the early phase of their tribal history.

The view of a kind of separation of the forest elephant from the African elephant did not go unchallenged. In 2003, based on genetic findings, a third species of elephant was postulated in western Africa, which is neither identical to the forest nor the African elephant. Other studies differentiated up to four taxonomic units within the genus Loxodonta . Analyzes, especially on the mitochondrial DNA , showed that the forest and African elephants share individual haplotypes . Accordingly, there is a more or less broad hybridization corridor in the contact area of ​​the distribution areas of the two African elephant forms, for example in the western and central areas of the continent. The mixing of forest and African elephants is not only genetically identifiable, but can also be proven by morphological features. Some researchers use this hybrid formation as an argument against the independence of the forest elephant, since a mixture would not be compatible with the biological species concept. This creates complex phylogeographical and family relationships within the genus Loxodonta , which do not support the existence of two or even three species. However , if the West and Central African hybrid populations are neglected, the genus Loxodonta shows two genetically clearly distinguishable lines, so that the forest and African elephants can each be viewed as separate species despite the existing gene exchange.

On the problem of the "dwarf elephant"

In 1906 Theophil Noack presented a very small, female individual of only 120 cm shoulder height from the area of ​​what is now the Republic of the Congo , who was at the time in the Hamburg Zoo. He referred this to the form Elephas africanus pumilio , which he regarded as a "dwarf elephant ". In addition to the small body size, Noack gave, among other things, the different shape of the ears, the much smoother skin and the laterally protruding tusks as special features. Henri Schouteden introduced another very small form only seven years later using an animal from Lake Mai-Ndombe and named it Elephas africanus fransseni . Schouteden postulated an aquatic way of life for the new subspecies ( l'éléphant d'eau , about "water elephant"). L. fransseni was later equated with L. pumilio . The existence of the "dwarf elephant" has long been controversial. However, it was partially supported by the sighting of individually appearing, small individuals with less than 200 cm shoulder height and developed tusks. In the further course, individual additional features should be worked out, for example in the tip of the trunk, which in the "dwarf elephant" had a significantly wider lower finger than in the forest elephant. Various researchers advocated the separation of the "dwarf elephant" from the forest elephant, with the former having varying status as an independent species or as a subspecies. Others, however, refused and referred, among other things, to the fact that the type specimen of L. pumilio lived under the name "Congo" until 1915 after its transfer to New York and had meanwhile grown to over 200 cm shoulder height. Anatomical studies from 2000 on the skull material of L. pumilio and L. cyclotis could not determine any differences between the two forms. Genetic studies carried out a little later came to a similar conclusion, in which the "dwarf elephant" could not be differentiated from the forest elephant. Scientists today therefore assume that the sightings of supposed “dwarf elephants” are isolated young animals or dwarfed individuals of the forest elephant due to illness.

Threat and protection

The forest elephant is currently not listed as an independent species by the IUCN . It classifies the total population of African elephants as "endangered" ( vulnerable ). The Washington Convention on Endangered Species (CITES) also lists it together with the African elephant in Appendix I, which prohibits international commercial trade in the animals. In general, the forest elephant is affected by the destruction of the tropical rainforests through clearing and road construction. Since the forest elephant avoids areas with strong human influence or activity, including traffic routes, this leads to the fragmentation of habitats and local populations. Another big influencing factor is poaching , mainly ivory hunting . In the second half of the 20th century, in particular, both factors affected the stock considerably. Its decline was largely hidden by the dense forest. The listing of African elephants in CITES did not change this fundamentally, as local authorities are often ineffective in combating poaching and illegal logging. Between 2002 and 2011 alone, the population size in central Africa decreased by an estimated 62% and only reached 10% of the possible population size. At this point in time, the forest elephant only settled about a quarter of the potentially habitual landscape. In 2011 alone, the forest elephant lost 3% of its total population due to illegal hunting, according to further estimates, which corresponds to around 40,000 animals killed. According to a wild animal census by the WWF in Cameroon, the Republic of the Congo, the Central African Republic and Gabon, the population in individual protected areas in the region fell by 51 to 90% locally between 2005 and 2016. Among the most important national parks, where the forest elephant is present, include the Dzanga-Ndoki National Park in the broader Dzanga-reserve in the Central African Republic , the Loango National Park and the National Park Lope in Gabon , the Odzala National Park in the Republic of Congo and the Okapi Game Reserve in the Democratic Republic of the Congo .

literature

  • Andrea Turkalo and Richard Barnes: Loxodonta cyclotis Forest Elephant. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London 2013, pp. 195-200.
  • Don E. Wilson and DeenAnn M. Reeder: Mammal Species of the World. A taxonomic and geographic reference. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 .
  • G. Wittemyer: Family Elephantidae. In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, ISBN 978-84-96553-77-4 , pp. 50-79 (pp. 77-78).

Individual evidence

  1. ↑ a b c d e f g h i j k l m n o p Andrea Turkalo and Richard Barnes: Loxodonta cyclotis Forest Elephant. In: Jonathan Kingdon, David Happold, Michael Hoffmann, Thomas Butynski, Meredith Happold and Jan Kalina (eds.): Mammals of Africa Volume I. Introductory Chapters and Afrotheria. Bloomsbury, London, 2013, pp. 195-200.
  2. ↑ Bethan J. Morgan and PC Lee: Forest elephant (Loxodonta africana cyclotis) stature in the Réserve de Faune du Petit Loango, Gabon. Journal of Zoology 259, 2003, pp. 337-344.
  3. ↑ a b c d Peter Grubb, Colin P. Groves, Joseph P. Dudley and Jeheskel Shoshani: Living African elephants belong to two species: Loxodonta africana (Blumenbach, 1797) and Loxodonta cyclotis (Matschie, 1900). Elephant 2 (4), 2000, pp. 1-4.
  4. ^ A b Bethan J. Morgan: Group size, density and biomass of large mammals in the Réserve de Faune du Petit Loango, Gabon. African Journal of Ecology 45, 2007, pp. 508-518.
  5. ↑ a b c d e f g h i j k l m n o G. Wittemyer: Family Elephantidae. In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 2: Hooved Mammals. Lynx Edicions, Barcelona 2011, ISBN 978-84-96553-77-4 , pp. 50-79 (pp. 77-78).
  6. ^ A b Alfred L. Roca, Nicholas Georgiadis, Jill Pecon-Slattery, and Stephen J. O'Brien: Genetic evidence for two species of elephant in Africa. Science 293 (5534), 2001, pp. 1473-1477.
  7. ↑ a b c Régis Debruyne: A case study of apparent conflict between molecular phylogenies: the interrelationships of African elephants. Cladistics 21, 2005, pp. 31-50.
  8. ^ A b Yasuko Ishida, Taras K. Oleksyk, Nicholas J. Georgiadis, Victor A. David, Kai Zhao, Robert M. Stephens, Sergios-Orestis Kolokotronis and Alfred L. Roca: Reconciling Apparent Conflicts between Mitochondrial and Nuclear Phylogenies in African Elephants . PloS ONE 6 (6), 2011, p. E20642, doi: 10.1371 / journal.pone.0020642 .
  9. ↑ Jörn Theuerkauf, Hermann Ellenberg, Wolf Ekkehard Waitkuwait and Michael Mühlenberg: Forest elephant distribution and habitat use in the Bossematié Forest Reserve, Ivory Coast. Pachyderm 30, 2001, pp. 37-43.
  10. ↑ Ralph Buij, William J. McShea, Patrick Campbell, Michelle E. Lee, Francisco Dallmeier, Sylvain Guimondou, Loïc Mackaga, Nicaise Guisseougou, Serge Mboumba, James E. Hines, James D. Nichols and Alfonso Alonso: Patch-occupancy models indicate human activity as major determinant of forest elephant Loxodonta cyclotis seasonal distribution in an industrial corridor in Gabon. Biological Conservation 135, 2007, pp. 189-201.
  11. ↑ Stephen Blake, Sharon L. Deem, Samantha Strindberg, Fiona Maisels, Ludovic Momont, Inogwabini-Bila Isia, Iain Douglas-Hamilton, William B. Karesh and Michael D. Kock: Roadless Wilderness Area Determines Forest Elephant Movements in the Congo Basin. PLoS ONE 3 (10), 2008, p. E3546, doi: 10.1371 / journal.pone.0003546 .
  12. ↑ a b Andrea K. Turkalo, Peter H. Wrege and George Wittemyer: Long-term monitoring of Dzanga Bai forest elephants: forest clearing use patterns. PLoS ONE 8 (12), 2013, p. E85154, doi: 10.1371 / journal.pone.0085154 .
  13. ^ A b c Andrea K. Turkalo, Peter H. Wrege and George Wittemyer: Demography of a forest elephant population. PLoS ONE 13 (2), 2018, p. E0192777, doi: 10.1371 / journal.pone.0192777 .
  14. ^ A b C. Marechal, C. Maurois and C. Chamberlan: Size (and structure) of forest elephants groups (Loxodonta africana cyclotis Matschie, 1900) in the Odzala National Park, Republic of Congo: Mammalia 62 (2), 1998, Pp. 297-300.
  15. ↑ Bethan J. Morgan and PC Lee: Forest elephant group composition, frugivory and coastal use in the Réserve de Faune du Petit Loango, Gabon. African Journal of Ecology 45, 2007, pp. 519-526.
  16. ↑ a b Stephanie G. Schuttler, Alden Whittaker, Kathryn J. Jeffery S. and Lori Eggert: African forest elephant social networks: fission-fusion dynamics, but fewer associations. Endangered Species Research 25, 2014, pp. 165-173.
  17. ↑ Vicki Fishlock, Phyllis C. Lee and Thomas Breuer: Quantifying forest elephant social structure in Central African bai environments. Pachyderm 44, 2008, pp. 19-28.
  18. ↑ Vicki Fishlock and Phyllis C. Lee: Forest elephants: fission-fusion and social arenas. Animal Behavior 85, 2013, pp. 357-363.
  19. ^ A b S. Blake, I. Douglas-Hamilton and WB Karesh: GPS telemetry of forest elephants: results of a preliminary study. African Journal of Ecology 39, 2001, pp. 178-186.
  20. ↑ Peter H. Wrege, Elizabeth D. Rowland, Nicolas Bout and Modeste Doukaga: Opening a larger window Onto forest elephant ecology. African Journal of Ecology 50, 2011, pp. 176-183.
  21. ↑ Stephen Blake and Clement Inkamba-Nkulu: Fruit, Minerals, and Forest Elephant Trails: Do All Roads Lead to Rome? Biotropica 36 (3), 2004, pp. 392-401.
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  24. ↑ Michael A. Pardo, Joyce H. Poole, Angela S. Stoeger, Peter H. Wrege, Caitlin E. O'Connell-Rodwell, Udaha Kapugedara Padmalal and Shermin de Silva: Differences in combinatorial calls among the 3 elephant species cannot be explained by phylogeny. Behavioral Ecology 30 (3), 2019, pp. 809-820, doi: 10.1093 / beheco / arz018 .
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  37. ↑ a b Nadin Rohland, David Reich, Swapan Mallick, Matthias Meyer, Richard E. Green, Nicholas J. Georgiadis, Alfred L. Roca and Michael Hofreiter: Genomic DNA Sequences from Mastodon and Woolly Mammoth Reveal Deep Speciation of Forest and Savanna Elephants. PLoS Biology 8 (12), 2010, p. E1000564, doi: 10.1371 / journal.pbio.1000564 .
  38. ↑ a b Eleftheria Palkopoulou, Mark Lipson, Swapan Mallick, Svend Nielsen, Nadin Rohland, Sina Baleka, Emil Karpinski, Atma M. Ivancevic, Thu-Hien To, R. Daniel Kortschak, Joy M. Raison, Zhipeng Qu, Tat-Jun Chin, Kurt W. Alt, Stefan Claesson, Love Dalén, Ross DE MacPhee, Harald Meller, Alfred L. Roca, Oliver A. Ryder, David Heiman, Sarah Young, Matthew Breen, Christina Williams, Bronwen L. Aken, Magali Ruffier, Elinor Karlsson, Jeremy Johnson, Federica Di Palma, Jessica Alfoldi, David L. Adelson, Thomas Mailund, Kasper Munch, Kerstin Lindblad-Toh, Michael Hofreiter, Hendrik Poinar and David Reich: A comprehensive genomic history of extinct and living elephants. PNAS 115 (11), 2018, pp. E2566 – E2574, doi: 10.1073 / pnas.1720554115 .
  39. ↑ Yasuko Ishida, Natalie A. Gugala, Nicholas J. Georgiadis and Alfred L. Roca: Evolutionary and demographic processes shaping geographic patterns of genetic diversity in a keystone species, the African forest elephant (Loxodonta cyclotis). Ecology and Evolution 8, 2018, pp. 4919-4931.
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  44. ↑ Dieter Backhaus: On the variability of the external systematic characteristics of the African elephant (Loxodonta Cuvier, 1825). Mammalsundliche Mitteilungen 6 (4), 1958, pp. 166-173.
  45. ↑ Véronique Barriela, Estelle Thuet and Pascal Tassy: Molecular phylogeny of Elephantidae. Extreme divergence of the extant forest African elephant. Comptes Rendus de l'Académie des Sciences 322, 1999, pp. 447-454.
  46. ↑ Kenine E. Comstock, Nicholas Georgiadis, Jill Pecon-Slattery, Alfred L. Roca, Elaine A. Ostrander, Stephen J. O'Brien and Samuel K. Wasser: Patterns of molecular genetic variation among African elephant populations. Molecular Ecology 11 (12), 2002, pp. 2489-2498.
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  49. ↑ a b Yumie Murata, Takahiro Yonezawa, Ichiro Kihara, Toshihide Kashiwamura, Yuji Sugihara, Masato Nikaidoa, Norihiro Okada, Hideki Endo and Masami Hasegawa: Chronology of the extant African elephant species and case study of the species identification of the small African elephant with the molecular phylogenetic method. Gene 441, 2009, pp. 176-186.
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  64. ↑ George Wittemyer, Joseph M. Northrup, Julian Blanc, Iain Douglas-Hamilton, Patrick Omondi and Kenneth P. Burnham: Illegal killing for ivory drives global decline in African elephants. PNAS 111 (36), 2014, pp. 13117-13121, 2014.
  65. ↑ N'Goran Kouame Paul, Nzooh Dongmo Zacharie Laurent and Le-Duc Yeno Stephane: WWF biomonitoring activities from 2014 to 2016. Status of Forest Elephant and Great Apes in Central Africa Priority Sites. WWF, 2017, pp. 1–47 ( online as PDF ).

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