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. 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, while Groves (2005) in Mammal Species of the World listed three. 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. 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.
Physical description
The chacma baboon is perhaps the longest species of monkey, with an adult body length of and tail length of . It is also one of the heaviest; the male weighs from with an average of . Baboons are sexually dimorphic, and females are considerably smaller than males. The adult female chacma weighs from , with an average of . Adult males can in some instances be about twice as long and three times as heavy as adult females.Kingdon, J., Happold, D., Butynski, T., Hoffmann, M., Happold, M., & Kalina, J. (2013). Mammals of Africa (Vol. 1). A&C Black.Coid, C., Poilecot, P., & de Zborowski, I. (2002). Les hommes et les animaux dans la moyenne vallée du Zambèze, Zimbabwe. Editions Quae. 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 more than a chacma baboon, the females weigh 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. 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. The canine teeth of male chacma baboons have a mean length of 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.
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. 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. 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.
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. Baboons are considered vermin by most African farmers due to their foraging and damage to cultivated crops and livestock. At the Cape of Good Hope in particular, chacma baboons are also known for taking shellfish and other small marine invertebrates. 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. 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.
Predation
Despite their formidable nature and large size, chacma baboons are vulnerable to a variety of predators.Nowak, R. (1999). Walker's Mammals of the World, Sixth Edition. Baltimore: The Johns Hopkins University Press. The main wild predator of adult chacma baboons is the leopard.Cowlishaw, G. (1994). Vulnerability to predation in baboon populations. Behaviour, 131(3–4), 293–304.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. In the Waterberg Biosphere, chacma baboon comprised 20.2% of leopard kills and 18.7% of the leopard's prey biomass.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. 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.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. 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).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.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.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. The predators of infant and juvenile chacma baboons are probably even more diverse but poorly documented. 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.Gargett, V., Mundy, P. J., & Arnott, G. (1990). The Black Eagle: A Study: Verreaux's Eagle in Southern Africa. Academic.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.
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.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. 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.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.
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.
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. 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 than other baboon species, as newly dominant males may kill infants or young baboons sired by the previously dominant male. Baboon troops possess a complex group behavior and communicate by means of body attitudes, facial expressions, vocalizations and touch.
Reproduction Chacma baboons do not have a specific breeding season; they breed through the year. On average, males and females reach sexual maturity around 5 years, but males typically don't breed successfully until they are large enough to challenge other males, around 7 to 10 years old. Mothers give birth on average every 1.5 to 2 years and usually have only one infant at a time. It takes about one year for those infants to reach independence.
Morning dispersal patterns