Pan troglodytes (Blumenbach, 1775)
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https://doi.org/ 10.5281/zenodo.6700973 |
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DOI |
https://doi.org/10.5281/zenodo.6700585 |
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persistent identifier |
https://treatment.plazi.org/id/03FA8785-4000-9F63-FF35-F750F5DBB688 |
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Jonas |
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scientific name |
Pan troglodytes |
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Chimpanzee
French: Chimpanzé / German: Schimpanse / Spanish: Chimpancé
Other common names: Chimpanzee, Common Chimpanzee, Robust Chimpanzee; Central Chimpanzee (troglodytes), Eastern Chimpanzee (schweinfurthii), Nigeria-Cameroon Chimpanzee (elliot), Western Chimpanzee (verus)
Taxonomy. Simia troglodytes Blumenbach, 1775 View in CoL ,
Angola.
There are few morphological differences among the four, somewhat ill-defined, subspecies, but mtDNA analyses indicate that they are distinct from one another. Four subspecies are recognized.
Subspecies and Distribution.
P. t. elliotMatschie, 1914 — SENigeriaandW & CCameroon.
P. t. verus Schwarz, 1934 — S Senegal, SW Mali, Guinea Bissau, Guinea, Sierra Leone, Liberia, Ivory Coast, Ghana, and SWNigeria; extinct in Gambia, andpossibly extinct in Burkina Faso, Togo, and Benin. View Figure
Descriptive notes. Head-body 77-96 cm (males) and 70-91 cm (females); weight 28-70 kg (males) and 20-50 kg (females). The Chimpanzee is sexually dimorphic. Like all catarrhine primates, mature chimpanzees have a 12/2, C1/1,P 2/2, M 3/3 (x2) dental formula. Body hair is long andblack, often turning gray with age on rump, back and chins of both sexes. Female Chimpanzees, in particular, have a tendencyto go bald on the crown. Ears are large, and browridges are well developed and generally somewhat raised. Chimpanzees share a wide rangeoffacial expressions with their human relatives, although their forehead musculatureis less well developed and their lips more flexible. Chimpanzees typically travel on all fours both terrestrially and arboreally. Their form of quadrupedal locomotion involves knuckle-walking. Since their arms are longer than their legs, chimpanzees use their knuckles for support while walking on the soles oftheir feet. Chimpanzees are accomplished climbers; they are also able to brachiate or swing using their powerful arms and to cling and hang from branches using any oftheir four limbs, which are equipped with opposable toes or thumbs. Theyare also capable of bipedal locomotion, which they perform most often overshort distances when carrying objects ortravelling arboreally. Face, ears, hands, feet, and anogenital region are naked and normally flesh-colored, although the skin on the face darkens with age. The “Central Chimpanzee” (P. t. troglodytes ) tends to be larger than the other three subspecies, especially the males, but variation within subspecies is greater than between them.
Habitat. Chimpanzees have the widest geographic distribution of any great ape. They are found discontinuously across the forest belt of Africa, occupying mature, moist, closed-canopy lowland, submontane, montane, secondary, swamp, and galleryforests. They inhabit dry forest, and savanna-woodland mosaic habitats in the drier extremes oftheir distribution. The maximum confirmedelevational limits for three of the subspecies are 1607 m for the “Western Chimpanzee” (P. (. verus), ¢.2000 m for the “Nigeria-Cameroon Chimpanzee” (P. t. ellioti), and 2790 mfor the “Eastern Chimpanzee” (Pt. schweinfurthii).
Food and Feeding. Chimpanzees are omnivorous and opportunistic feeders; some communities include as manyas ¢.200 different fooditems in their diet. J. Goodall’s study at Gombe, Tanzania, was seminal in demystifying two human “trademarks”— the use oftools andsocial hunting of mammal prey. It is now well established that Chimpanzees use tools throughout their range and hunt and eat meat to varying degrees. The dietary repertoire and food processing techniques of each Chimpanzee communitycan differ quite remarkably across communities. Fruit, however, forms the bulk ofthe diet. It is typically supplemented with terrestrial herbaceous vegetation, leaves, stems, seeds, flowers, bark, pith, honey, mushrooms, resin, eggs, and animal prey such as insects and medium-sized mammals. Chimpanzees eat more than 30 species of mammals, mainly primates such as the red colobus (Procolobus), a favored prey of some communities. Theyare the most carnivorous ofthe great apes. Although Chimpanzees are renowned hunters, the degree of cooperation involved in social hunting sprees varies across communities. Adult male Chimpanzees often coordinate their movements when pursing target preyin order to maximize capture success. Prey are usually pursued, captured, and killed by adult males who share the meat with other members of the community, especially participant hunters and adult females. Chimpanzee males may also share wild or cultivated fruit items with sexually mature females. Communities living in highly degraded and fragmented habitats regularly crop-raid for cultivated foods, especially during periods offruit scarcity; as many as 36 different cultivar species are eaten by Chimpanzees across their range. Chimpanzees are also proficient tool users, with each community presenting its own signature set of tool-use behaviors, parsimoniously interpreted as evidence for culture in the species. Tool use by Chimpanzees serves multiple functions and purposes, including hygiene, defense, communication, exploration, reaching, and comfort. However, most tool use occurs in a subsistence context aimed at animal prey and/or embedded foods. In Senegal, Chimpanzees, especially females, use sharp sticks to skewer galagos living in tree holes. Western Chimpanzee communities as far East as Cameroon employ a mobile or embedded stone anvil and wooden clubs or stones to crack open nuts. Most known populations excel in extractive foraging of insects or their honey. They commonly target aggressive ants or termites using flexible probes of vegetation to lure insects from earthen mounds, underground nests or arboreal hollows. Chimpanzees in some locations also dig up tubers with the aid ofsticks or pieces of bark. Although most tool use involves the manufacture and/or use of a single tool, some communities specialize in the use of a tool set. A tool set often implies the compulsory sequential use of two types of tool to attain a specific goal; for example, one stout tool is used to perforate the termite mound and another more flexible slender tool to fish for termites from the newly created passageway.
Breeding. Male and female Chimpanzees reach puberty at 7-8 years of age. Males gain most muscle mass and testicular volume by 15 years of age. During a c.35day menstrual cycle, females have a large, pink perineal swelling that persists for 10-12 days and varies in firmness and attractiveness to males, reaching maximum volume and turgidity around ovulation. The first menses is followed by a 2-3year period of adolescent infertility. Mating is opportunistic, and a proceptive female may copulate frequently with numerous males in her community. The first parturition is generally at 13-14 years of age, but as early as 9-5 years in one population of Western Chimpanzees. Chimpanzees reproduce throughout the year, with peaks in birthrate following conception during seasons of abundant food. Gestation is ¢.230 days. The norm is a single infant, but occasionally twins are born. Females carry their infants ventrally in the early months. Infants begin to travel dorsally within a few weeks of birth. Suckling causes lactational amenorrhea. Offspring share their mothers’ night nests until they are weaned at 4-5 years of age, or until the next sibling is born. The interbirth interval averages 4-6-7-2 years when the preceding infant survives. Females can remain reproductive into their late forties. Maximum life span is unknown, but it is thought to be c.50 years. Female Chimpanzees can give birth to as many as nine offspring during their lifetime, but on average only about 30% survive beyond infancy.
Activity patterns. The Chimpanzee is diurnal and semi-terrestrial. Activity budgets vary between sites (43-55% feeding, 12-14% traveling, and 25-39% resting). Every night they build a tree nest to sleep in, although, at some sites, some individuals nest on the ground. Chimpanzees also regularly construct terrestrial or arboreal nests for resting during the day. Chimpanzees often prefer certain nesting sites and habitat types, and are highly selective in their choice of nest tree species. Nest height varies from ground level to more than 40 m. Most nests are built at 10-20 m above the ground; however, nest height varies with vegetation type, season and community-specific nesting patterns. Searching for fruit in tropical forests requires spatial memory and mental mapping. Forest-dwelling Chimpanzees in Ivory Coast are known to travel efficiently and recurrently between preferred rare fruiting tree species. They also travel for longer when targeting known profitable and attractive food resources, which they generally revisit more often than expected. Chimpanzees are capable of memorizing individual locations of thousands of trees and preferred food sources.
Movements, Home range and Social organization. Chimpanzees live in multimale— multifemale, fission-fusion communities averaging 35 members. The largest known community has c.150 members. A single community varies its size by fissioning into smaller parties according to activity and resource availability (food and access to cycling females). Party sizes tend therefore to be smaller during periods of fruit scarcity. The most common aggregations are a mixture of males and females with immature offspring. Distance traveled daily averages 2-3 km, with occasional excursions exceeding 10 km. Savanna-dwelling chimpanzees generally range further daily than their forest-dwelling counterparts. Communities living in forest habitats have annual home ranges of 6-83-32 km?, while in savanna woodland, they range over much wider areas, often exceeding 65 km*. Typically, the community’s home range is defended by highly territorial males that patrol boundaries and may attack, and even kill, members of neighboring communities. Adult female Chimpanzees often spend time alone with their offspring or in a party with other females. Juveniles and adolescents most often travel with their mothers; young males spend increasing amounts of time with other males as they grow older. Females generally disperse from their natal group when they reach sexual maturity. Males typically remain in their natal group and are integrated into the male social hierarchy by 12-16 years old. Male Chimpanzees are dominant to females and are normally more gregarious. Males tend to develop strong selective bonds with one another, groom one another frequently, and often participate in cooperative activities such as boundary patrols and hunting. Linear dominance hierarchies among males are dynamic and are maintained via a complex web of affiliative and aggressive interactions. Males often form and use alliances to bolster their individual position in the hierarchy. Rank is generally maintained via aggressive displays toward subordinate individuals. Mutual grooming is thought to foster relationships and coalitions that can lead to or help maintain higher status.
Status and Conservation. CITES Appendix I. Classified as Endangered on The [UCN Red List, along with the four subspecies. Listed under Class A in the African Convention on the Conservation of Nature and Natural Resources. Chimpanzees are protected by national and international laws throughout their range, but enforcement is generally weak. Current total population size is unknown, and the quality of available information differs for each subspecies. The most threatened subspecies is the Nigeria-Cameroon Chimpanzee, numbering just 3500-9000 individuals. Next is the Western Chimpanzee, estimated in 2003 to number 21,300-55,600 individuals, with ¢.50% of the remaining individuals of this subspecies found in Guinea. In 2010, a national survey of Chimpanzees in Sierra Leone found a larger than anticipated population of 3100-10,400 individuals. Nevertheless, 90% of Chimpanzees in nearby Ivory Coast vanished between 1990 and 2007, and other countries of the region could have lost Chimpanzees at a comparable rate. Chimpanzees in Guinea have not been surveyed since 1998, and only a few hundred remain in Guinea-Bissau and Senegal. Numbers of Eastern Chimpanzees could be as high as 200,000-250,000 individuals, with the majority occurring over a wide area of DR Congo, Uganda, and Tanzania. Smaller populations occur in Burundi and Rwanda. The total number of Central Chimpanzees was last estimated in 2003 at 70,000-116,500 individuals, most of them in Cameroon, Gabon, and Republic of the Congo. Population declines have likely occurred throughout the species’ range; these have yet to be quantified. Recent surveys found several thousand Chimpanzees in Equatorial Guinea, ¢.20,000 in Gabon, and ¢.25,000 in the Republic of the Congo. Habitat loss and degradation due to agriculture, extractive industries (logging and mining), infrastructure development, and expanding human populations have been the major reasons for dramatic reductions in Chimpanzee numbers and distribution. Disease (Ebola) and poaching for the commercial bushmeat trade have decimated Central African populations, especially in north-eastern Gabon and western Republic of the Congo. Conservation organizations have programs throughout the species’ range and are working toward securing the Chimpanzee’s long-term survival.
Bibliography. Boesch & Boesch-Achermann (2000), Brncic et al. (2010), Butynski (2003), Conservation International & Max Planck Institute for Evolutionary Anthropology (unpublished data), Emery Thompson & Wrangham (2013), Gilby et al. (2008), Goodall (1986), Gross-Camp et al. (2009), Groves (2001), Humle (2011), Jungers & Susman (1984), Matsuzawa et al. (2011), Morbeck & Zihiman (1989), Morgan et al. (2011), Normand & Boesch (2009), Normand et al. (2009), Plumptre et al. (2010), Pusey et al. (2005), Ruffler & Muray (2012), Sugiyama & Fujita (2011), Tutin et al. (2005), Uehara & Nishida (1987), Whiten et al. (1999), Zihiman et al. (2008).
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