Indirect evidence has been found to indicate that chimpanzees in the Tomboronkoto region of southeastern Senegal use natural caves during the late dry season (May-June) for resting and eating. The Tomboronkoto region is the site of a newly-initiated research project on the ecology and behavior of savanna chimpanzees. Chimpanzees are not yet habituated at this site. Tomboronkoto (12¼72ÕN, 12¼22ÕW) is approximately 48 km SE of the Assirik site in Parc National du Niokolo Koba in Senegal. This new study site is south of the Gambia River, while the Assirik area lies north of the river. At Tomboronkoto, chimpanzees are sympatric with Bedik, Bassari, Malinke, and Fulani peoples. Although many of the animals known to occur in the Niokolo Koba Park also occur in Tomboronkoto, densities of mammals outside the park are comparatively low. The most commonly sighted mammal in the region is the patas monkey. Baboons occur at significantly lower levels in Tomboronkoto compared to Niokolo Koba. Predators that occur within the national park, such as lions, leopards, and spotted hyaenas do not occur in Tomboronkoto.