Chacma baboon

The chacma baboon (Papio ursinus), also known as the Cape baboon, is, like all other baboons, from the Old World monkey family. It is one of the largest of all monkeys. Located primarily in southern Africa, the chacma baboon has a wide variety of social behaviours, including a dominance hierarchy, collective foraging, adoption of young by females, and friendship pairings. These behaviors form parts of a complex evolutionary ecology. In general, the species is not threatened, but human population pressure has increased contact between humans and baboons. Hunting, trapping, and accidents kill or remove many baboons from the wild, thereby reducing baboon numbers and disrupting their social structure.

Taxonomy

Due to hybridization between different baboon (Papio) populations across Africa, authors have occasionally grouped the entire radiation as a single species, the hamadryas baboon, Papio hamadryas. Arbitrary boundaries were then used to separate the populations into subspecies.<ref name="Fleagle1999">Template:Cite book</ref> Other authors once considered the chacma baboon a subspecies of the yellow baboon, Papio cynocephalus, although it is now recognised as a separate species, Papio ursinus. The chacma baboon has two or three subspecies, depending on which classification is followed. Grubb et al. (2003) lists two subspecies,<ref name="Grubb2003">Template:Cite journal</ref> while Groves (2005) in Mammal Species of the World listed three.<ref name=msw3/> This article follows Groves (2005) and describes three distinct subspecies. In the Grubb et al. (2003) paper, P. u. raucana was believed to be synonymous with P. u. ursinus.<ref name="Grubb2003" />

• Papio ursinus ursinus Kerr, 1792 – Cape chacma (found in southern South Africa)
• P. ursinus griseipes Pocock, 1911 – Gray-footed chacma (found in northern South Africa to southern Zambia)
• P. ursinus raucana Shortridge, 1942 – Ruacana chacma (found from Namibia to southern Angola, but not accepted by all authorities as distinct.

• 
  P. u. ursinus
  Cape of Good Hope, South Africa
• 
  Male P. u. griseipes
  Chobe National Park, Botswana
• 
  Male P. u. griseipes
  Chobe National Park
• 
  Female P. u. griseipes
  Chobe
• 
  Juvenile P. u. griseipes
  Chobe

Physical description

Chacma baboon skeleton

The chacma baboon is perhaps the longest species of monkey, with an adult body length of Template:Cvt and tail length of Template:Cvt.<ref name="Nowak1991">Template:Cite book</ref><ref name="Estes1992">Template:Cite book</ref> It is also one of the heaviest; the male weighs from Template:Cvt with an average of Template:Cvt. Baboons are sexually dimorphic, and females are considerably smaller than males. The adult female chacma weighs from Template:Cvt, with an average of Template:Cvt. Adult males can in some instances be about twice as long and three times as heavy as adult females.<ref name="BurnieWilson2005">Template:Cite book</ref><ref name="Kingdon1993">Template:Cite book</ref><ref name=Kingdon2013>Kingdon, J., Happold, D., Butynski, T., Hoffmann, M., Happold, M., & Kalina, J. (2013). Mammals of Africa (Vol. 1). A&C Black.</ref><ref>Coid, C., Poilecot, P., & de Zborowski, I. (2002). Les hommes et les animaux dans la moyenne vallée du Zambèze, Zimbabwe. Editions Quae.</ref> It is similar in size to the olive baboon, averaging slightly higher in mean body mass, and of similar weight to the more compact mandrill, the males of which weigh on average about Template:Cvt more than a chacma baboon, the females weigh Template:Cvt less than the female chacma. While the mandrill is usually crowned the largest of all modern monkeys, going on total length and average (but not maximum) body weight between the sexes, the chacma baboon appears to be the largest extant monkey.<ref name= Kingdon2013/><ref name="Dechow1983">Template:Cite journal</ref> The chacma baboon is generally dark brown to gray in color, with a patch of rough hair on the nape of its neck. Unlike the males of northern baboon species (the Guinea, hamadryas, and olive baboons), chacma males do not have a mane. Perhaps the most distinctive feature of this baboon is its long, downward-sloping face.<ref name="Jolly1993">Template:Cite book</ref><ref name="Groves2001">Template:Cite book</ref> The canine teeth of male chacma baboons have a mean length of Template:Cvt at the time they emigrate from their natal troop. This is the time of greatest tooth length as the teeth tend to wear or be broken thereafter.<ref name="HamiltonBulger1990">Template:Cite journal</ref>

The three subspecies are differentiated by size and color. The Cape chacma is a large, heavy, dark-brown, and has black feet. The gray-footed chacma is slightly smaller than the Cape chacma, lighter in color and build, and has gray feet. The Ruacana chacma generally appears to be a smaller, less darkly colored version of the Cape chacma.

Ecology

Habitat and distribution

The chacma baboon inhabits a wide array of habitats including woodland, savanna, steppes, and sub desert, from the grassy alpine slopes of the Drakensberg to the Kalahari Desert.<ref name="iucn status 19 November 2021" /> During the night, the chacma baboon sleeps atop steep hills, high cliffs or rocks or in large trees, away from nocturnal predators. In daytime, water availability may limit its range in arid areas.<ref name="iucn status 19 November 2021" /> It is found throughout southern Africa, ranging from South Africa north to Angola, Zambia, and Mozambique. The subspecies are divided across this range. The Cape chacma is found in southern South Africa; the gray-footed chacma, is present from northern South Africa, through the Okavango Delta in Botswana, Zimbabwe, Mozambique (south of the Zambezi), to southwest Zambia; and the Ruacana chacma is found in northern Namibia and southern Angola.<ref name="iucn status 19 November 2021" />

Diet

The chacma baboon is an omnivorous highly opportunistic feeder, and will eat practically anything; typical foods include fruits, seeds, grass, blossoms, bulbs, bark, insects, spiders, worms, grubs, rodents, birds, small antelope and fungi (the desert truffle Kalaharituber pfeilii). Chacma baboon diet is thought to contain about 2 percent animal-sourced food, most of which consists of invertebrates; proportions vary between populations.<ref>Template:Cite thesis</ref> Baboons are considered vermin by most African farmers due to their foraging and damage to cultivated crops and livestock.<ref>Template:Cite journal</ref> At the Cape of Good Hope in particular, chacma baboons are also known for taking shellfish and other small marine invertebrates.<ref>Template:Cite journal</ref> It is generally a scavenger when it comes to game meat, and rarely engages in hunting larger animals. One incident of a chacma baboon killing a human infant has been reported, but the event is so rare, the locals believed it was due to witchcraft.<ref name="Dhlamini2003">Template:Cite web</ref> Normally, wild chacma baboons will flee at the approach of humans, though this is changing due to the easy availability of food and garbage from human dwellings in villages and towns near the baboons' habitat.<ref name="Thomas2006">Template:Cite web</ref>

Predation

Trapped up tree by Kalahari lions
Tswalu Kalahari Reserve, South Africa

Despite their formidable nature and large size, chacma baboons are vulnerable to a variety of predators.<ref name= Nowak>Nowak, R. (1999). Walker's Mammals of the World, Sixth Edition. Baltimore: The Johns Hopkins University Press.</ref> The main wild predator of adult chacma baboons is the leopard.<ref name= Cowlishaw>Cowlishaw, G. (1994). Vulnerability to predation in baboon populations. Behaviour, 131(3–4), 293–304.</ref><ref>Noser, R., & Byrne, R. W. (2007). Travel routes and planning of visits to out-of-sight resources in wild chacma baboons, Papio ursinus. Animal Behaviour, 73(2), 257–266.</ref> In the Waterberg Biosphere, chacma baboon comprised 20.2% of leopard kills and 18.7% of the leopard's prey biomass.<ref>Jooste, E., Pitman, R. T., Van Hoven, W., & Swanepoel, L. H. (2012). Unusually high predation on chacma baboons (Papio ursinus) by female leopards (Panthera pardus) in the Waterberg Mountains, South Africa. Folia Primatologica, 83(3–6), 353–360.</ref> Although previously little documented, the African wild dog, a predator of similar or even slightly inferior size to male baboons themselves, in Mana Pools National Park (Zimbabwe) took to chacma baboons as their main prey, comprising 44% of 118 kills.<ref name= vanderMeer>van der Meer, E., Lyon, N., Mutonhori, T., Mandisodza-Chikerema, R., & Blinston, P. (2019). Dangerous game: preferential predation on baboons by African wild dogs in Mana Pools National Park, Zimbabwe. Behaviour, 156(1), 37–58.</ref> Less routine predation on chacma baboons has been reportedly committed by lions, spotted hyena, Nile crocodiles and Southern African rock pythons (in rough descending likelihood of threat).<ref name= Cowlishaw/><ref name= Owen-Smith>Owen-Smith, N., & Mills, M. G. (2008). Predator–prey size relationships in an African large-mammal food web. Journal of Animal Ecology, 77(1), 173–183.</ref><ref>Cheney, D., & Wrangham, R. (1987). Predation. pp. 227–239 in B Smuts, D Cheney, R Seyfarth, R Wranghams, T Struhsaker, eds. Primate Societies. Chicago: The University of Chicago Press.</ref><ref>Cheney, D. L., Seyfarth, R. M., Fischer, J., Beehner, J., Bergman, T., Johnson, S. E., & Silk, J. B. (2004). Factors affecting reproduction and mortality among baboons in the Okavango Delta, Botswana. International Journal of Primatology, 25(2), 401–428.</ref> The predators of infant and juvenile chacma baboons are probably even more diverse but poorly documented.<ref name= Nowak/><ref name= Cowlishaw/> It is documented that Verreaux's eagles and martial eagles have taken young chacma baboons and probable or possible predation has been committed by other eagles: crowned eagles and tawny eagles.<ref name= Cowlishaw/><ref name= Owen-Smith/><ref>Gargett, V., Mundy, P. J., & Arnott, G. (1990). The Black Eagle: A Study: Verreaux's Eagle in Southern Africa. Academic.</ref><ref>Naude, V. N., Smyth, L. K., Weideman, E. A., Krochuk, B. A., & Amar, A. (2019). Using web-sourced photography to explore the diet of a declining African raptor, the Martial Eagle (Polemaetus bellicosus). The Condor: Ornithological Applications, 121(1), duy015.</ref>

When approaching potentially dangerous sites such as watering holes, more vulnerable members of the chacma baboon group may travel near the rear of the group but may conversely end up by the front of group out of fear if a predator approaches.<ref>Rhine, R. J., & Tilson, R. (1987). ;;Reactions to fear as a proximate factor in the sociospatial organization of baboon progressions;;. American Journal of Primatology, 13(2), 119–128.</ref> The adult male chacma baboon has a fearsome defense and may assault their predators with their large, sharp canine teeth, which can seriously injure predators as formidable as leopards, and (despite being far from exempt from predation) the adult males tend to be the least vulnerable members of the baboon troops. As in other monkeys, the larger, more formidable male baboons may successfully defend more vulnerable members of the troop via attacking predators if they come into sight.<ref name="Nowak" /><ref name="vanderMeer" /><ref>Melnick, D. & Pearl, M. (1987). Cercopithecines in multimale groups: Genetic diversity and population structure. pp. 121–134 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago: The University of Chicago Press.</ref>

Behaviour

Social organisation

The chacma baboon usually lives in social groups, called troops, which are composed of multiple adult males, adult females, and their offspring. Occasionally, however, very small groups form that consist of only a single adult male and several adult females.<ref name="Byrne1987">Template:Cite journal</ref>

Chacma troops are characterized by a dominance hierarchy. Female ranking within the troop is inherited through the mother and remains relatively fixed, while the male ranking is often in flux, especially when the dominant male is replaced. Chacmas are unusual among baboons in that neither males nor females form strong relationships with members of the same sex. Instead, the strongest social bonds are often between unrelated adult males and females. Infanticide is much more common among Chacmas compared to most other baboon species, as newly dominant males will often kill infants or young baboons sired by the previously dominant male.<ref name="HenziBattett2003">Template:Cite journal</ref> Baboon troops possess a complex group behavior and communicate by means of body attitudes, facial expressions, vocalizations and touch.

Morning dispersal patterns

Print of the large foot (pes) in sand, revealing i.a. the heel and thumb. The manus print in contrast reveals only the knuckles, the short, straight fingers and tip of the partly opposable<ref name="hunt1">Template:Cite journal</ref> thumb.

The chacma baboon often sleeps in large groups on high rocks, cliffs or in tall trees at night to avoid nocturnal predators. The morning dispersal from the sleeping site is synchronized, with all members leaving at the same time. In most cases, dispersal is initiated by a single individual, and the other members of the group decide whether or not to follow. At least five followers must be recruited for a successful dispersal initiation, and not all initiation attempts are successful. Surprisingly, the initiator's dominance status shows little correlation with successful initiation of departure; more-dominant individuals are no more likely to lead a successful departure than subordinate individuals. One study has shown that while the success rate of dispersal initiation attempts is relatively constant across all sexes, male are more likely to attempt initiation than females, and lactating females are less likely to attempt initiation than females without dependent offspring.<ref name="SteuckleZinner2009">Template:Cite journal</ref> A separate study has achieved slightly different results. While the dominance hierarchy does not play a significant role in initiating the morning dispersal, social affiliation does. Chacma baboons that play a more central role in the group (as measured by grooming behavior and time spent with other members) are more likely to be followed during the morning dispersal. This study concluded that group members are more likely to follow the behavior of individuals with which they are closely affiliated.<ref name="King_etal2011">Template:Cite journal</ref>

Foraging behaviour

Dominance does play a role in group foraging decisions. A dominant individual (usually the alpha male) leads the group to easily monopolised resources. The group usually follows, even though many subordinate members cannot gain access to that particular resource. As in morning dispersal, the inclination of group members to follow the leader is positively associated with social interactions with that dominant individual.<ref name="King_etal2008">Template:Cite journal</ref>

Collective foraging behaviour, with many individuals taking advantage of the same resource at once, has also been observed. However, this behavior can be chiefly attributed to shared dietary needs rather than social affiliation. Pregnant females, who share similar dietary needs, are more likely to synchronise their behaviour than fertile females. Foraging synchronization decreases in areas with lower food density.<ref name="King Cowlishaw 2009">Template:Cite journal</ref>

Adoption

Chacma baboons have been observed to adopt orphaned young.

Adoption behaviour has been observed in chacma baboons. Orphaned baboons whose mothers have died or disappeared are often too small to care for themselves. In one study of nine natural orphans and three introduced orphans, all but one orphan were adopted by another member of the troop. The individual that was not adopted was 16 months old, four months older than the next oldest orphan, and was old enough to survive on its own. Adoption behaviour includes sleeping close to the orphaned infant, grooming and carrying the orphan, and protecting it from harassment by other members of the troop. Both males and females care for infants, and care does not depend on the infant's sex. Additionally, nearly all caregivers are pre-reproductive, only four or five years of age. The two major theories explaining this behavior are kin selection, in which caregivers take care of potentially related orphans, and parental practice, in which young baboons increase their own fitness by using an orphan to practice their own parenting skills.<ref name="Hamilton_etal1982">Template:Cite journal</ref>

Friendship

Chacma baboons mating at Cape Point in South Africa

Males and female chacma baboons often form relationships referred to as "friendships". These cooperative relationships generally occur between lactating females and adult males. The females are believed to seek out male friendships to gain protection from infanticide. In many baboon species, immigrant alpha males often practice infanticide upon arrival in a new troop. By killing unrelated infants, the new male shortens the time until he can mate with the females of the troop. A female with dependent offspring generally does not become sexually receptive until she weans her offspring at around 12 months of age. However, a mother usually becomes sexually receptive shortly after the death of her offspring.<ref name="Engh_etal2006">Template:Cite journal</ref>

Grooming strengthens bonds between individuals in groups

This protection hypothesis is supported by studies of stress hormones in female baboons during changes in the male hierarchy. When an immigrant male ascends to the top of the male dominance hierarchy, stress hormones in lactating and pregnant females increases, while stress hormones in females not at risk of infanticide stay the same. Additionally, females in friendships with males exhibit a smaller rise in stress hormones than do females without male friends.<ref name="Beehner_etal2005">Template:Cite journal</ref>

The benefits of friendship to males are less clear. A male is more likely to enter into friendships with females with which he has mated, which indicates males might enter into friendships to protect their own offspring and not just to protect that female's future reproductive success.<ref name="Moscovice_etal2010">Template:Cite journal</ref> These friendships may play a role in the mating system of chacma baboons. A female will often mate with several males, which increases the number of potential fathers for her offspring and increases the chances she will be able to find at least one friend willing to protect her infants and assist in caring for them.<ref name="Clarke_etal2009">Template:Cite journal</ref>

Female chacma baboons have been observed to compete with each other for male friends. This may be the result of one male having a high probability of paternity with multiple females. These competitions are heavily influenced by the female dominance hierarchy, with dominant females displacing subordinate females in friendships with males. Generally, when a more-dominant female attempts to make friends with an individual which is already the friend of a subordinate female, the subordinate female reduces grooming and spatial proximity to that male, potentially leaving her offspring at higher risk of infanticide.<ref name="Palombit_etal2001">Template:Cite journal</ref>

Relationship with humans

Conservation

Chacma baboons live in proximity to humans and are frequently killed as vermin.

The chacma baboon does not rank among threatened animal species. However, in some confined locations, such as South Africa's Southern Cape Peninsula, local populations are dwindling due to habitat loss and predation from other protected species, such as leopards and lions.<ref name="Busse1980">Template:Cite journal</ref> Many troops have become a suburban menace in their search for food, overturning garbage cans, and breaking into cars and houses where they cause much damage. These troops can be dangerous and aggressive, and they will even steal food directly from people. These negative encounters have resulted in the baboons being hunted and poisoned by frustrated local residents. This isolated population is thought to face extinction within 10 years.<ref name="Thomas2006" />

The chacma is listed under Appendix II of CITES as it occurs in many protected areas across its range.<ref name="iucn status 19 November 2021" /> The only area in South Africa where they are monitored is in the Cape Peninsula, where they are protected.

Observations by those working hands-on in South Africa's rehabilitation centers have found this species is damaged by human intervention; troop structures are influenced, and over the years a significant loss in numbers has occurred. Because they live near and invade human habitats, urban baboons are regularly shot, poisoned, electrocuted, beaten to death, struck by cars and captured for research laboratories and muti (medicine).<ref>Template:Cite web</ref> Despite this, assessors working for the IUCN believe there are no major threats that could result in a range-wide decline of the species.<ref name="iucn status 19 November 2021" />

See also

• Fred the baboon
• Jack the Signalman

External links

• Cape Peninsula Baboon Research Unit
• Darwin Primate Group
• Imfene Baboon Conservation and Education Centre