Study site
Our research is conducted in the Moremi Game Reserve, which lies in the Okavango Delta in the northwest corner of the Republic of Botswana. The study site experiences dramatic ecological changes during the year. Between June and October, rainfall from Angola causes the Boro River to overflow its banks. Grasslands throughout the delta are flooded, leaving elevated ‘islands' edged with woodland. Islands can be less than one to hundreds of hectares in size. Baboons ford the submerged plains and move between islands throughout an approximately 5 square km range, feeding on the fruit of African mangosteen and jackalberry (African ebony) trees. Between November and May, flood waters evaporate and the baboons feed on open grasslands as well as on wild figs, sycamore figs, sausage trees, marula trees, camelthorn acacias, candle-pod acacias, knobthorn acacias, and real fan palms. They also opportunistically hunt birds, rodents, small ungulates, and vervet monkeys. Known predators of baboons include leopards, lions, and crocodiles. The population density of baboons in the Okavango is approximately 24 individuals per square km, considerably higher than in other areas of Africa.
Baboons in the Moremi Game Reserve were first studied by W.J. Hamilton (University of California, Davis) during the 1970s and 80s. In 1992, Dorothy Cheney and Robert Seyfarth began a long-term research project focusing on one of the groups initially observed by Hamilton and colleagues. The main study group (C) contains approximately 80 individuals, including up to 12 adult males and 25 adult females. We intermittently observe a second neighboring group. The baboons are individually recognizable and habituated to close-range observation by humans on foot.
As in most species of Old World monkeys, male baboons usually leave the groups in which they are born and immigrate to neighboring groups. Females remain in their natal groups throughout their lives. Matrilineal kinship is known for all individuals in group C.
The primary determinants of female reproductive success in the Okavango Delta are predation and infanticide. These two selective pressures affect female of all ranks. There is a slight, but non-significant correlation between female rank and reproductive success.
Our research is conducted under the auspices of the Office of the President and the Department of Wildlife and National Parks of the Republic of Botswana. The project is currently supported by a grant from the National Institute of Mental Health (NIMH). It has also been supported by grants from the National Science Foundation, the Louis Leakey Foundation, and the University of Pennsylvania.
