Bioacoustics of Papio ursinus

Food and Feeding. The Chacma Baboon is an opportunistic omnivore, and its diet varies locally. If available, Chacma Baboons feed on fruits, young leaves, flowers, tuberous roots, bulbs, grasses, bark, twigs, sap, mushrooms, lichens, seeds, shoots, buds, aquatic plants, and seashore animals (e.g. crustaceans, mussels, and snails). Other animal prey is also taken, including invertebrates such as insects and larger vertebrates such as lizards, birds, and small mammals. Occasionally, they may take small antelopes and the young of impala (Aepyceros). Crops (maize, tomatoes, citrus, and root crops) and garbage dumps are raided in settled areas. Lambs and small livestock are taken in some ranching areas. They often beg for food from tourists or take food from houses. Breeding. Births of Chacma Baboons occur throughout the year. The mean length of the menstrual cycle at De Hoop, South Africa,is 39-7 days. In Moremi (Okavango), females have their first infant at six years and nine months of age. The interbirth interval is 22-39 months, but it is longer in the Drakensberg Mountains. The dominant male of the group tries to monopolize access to sexually receptive females. A male and a female form a temporary consortship, and most mating happens during these consort periods. In contrast to Yellow ( P. cynocephalus ) and Olive ( P. anubis ) baboons, a consorting male Chacma Baboon is rarely challenged by other males, and male consort partners do not change often during receptive periods of a female. Males also do not form coalitions to take over a sexually receptive female from the dominant male, as they do in Yellow and Olive baboons. Hence, paternity probability for a particular male Chacma Baboon is higher than in Olive and Yellow baboons, which may be a reason why rates of infanticide are higher in Chacma Baboons than other baboon species. In some populations, more than 30% of the infants are killed by males. Females give copulation calls; they vocalize during or shortly after copulation. These calls are much louder than those of female Hamadryas ( P. hamadryas ) or Guinea (PF. papio ) baboons.

Movements, Home range and Social organization. Depending on ecological conditions and group sizes, the home range sizes of Chacma Baboons vary substantially (1-37 km?). Average daily movements are 3-6-8-5 km (range 2-13 km). Group size averages 20-80 individuals, but it can be as large as 130 individuals. The ratio of males to females is 1:1-5-10-3. As in Yellow and Olive baboons, the social organization is multimale-multifemale, although Chacma Baboons tend to have smaller groups. Groups are not substructured into one-male units, as they are in Hamadryas Baboons or Geladas ( Theropithecus gelada ). Solitary one-male units of Chacma Baboons, consisting of a few females and a single male, have been observed rarely, but a survey in the Drakensberg Mountains found that such one-male units made up 50% of groups above 2100 m. Females remain in their natal groups and form linear dominance hierarchies. Males also establish a dominance hierarchy that usually regulates access to sexually receptive females. Most males emigrate from their natal groups and attain high rank after joining a new group. Male Chacma Baboons may fight vigorously for a dominant position. Before they start fighting, they often have vocalization contests, running up and down producing their specific loud calls, the “wahoo.” These contests are believed to signal power and stamina to opponents. As in Yellow Baboons, the social network among related females is the most stable social structure. Grooming and other affiliative behavior occur predominantly within these networks. Studies suggest that these tight relationships provide a fitness advantage for females. Females with a tighter network live longer and reproduce more successfully. Females and males may also form bonds outside sexual consortships, called “friendships.” These relationships likely benefit a female via protection for herself and her offspring against sexual harassment and infanticide by other males. The male benefits because it may protect its own offspring or it may invest in future sexual relationship with the respective females. Densities of Chacma Baboons can range from one to more than 24 ind/km? in some protected areas.