DIET OF SAVANNA CHIMPANZEES IN THE UGALLA AREA, TANZANIA

We studied the diet of chimpanzees (Pan troglodytes) in the Ugalla savanna woodland area of western Tanzania. This area is the most eastern habitat and one of the driest and most open habitats of chimpanzees. Field surveys were conducted mainly at the Nguye and Bhukalai sites in Ugalla from 1995 to 2011, during which we collected 465 feces of chimpanzees. From the discernable components of the Ugalla chimpanzees' diet in the fecal samples we collected and recorded, we compared the diet of these chimpanzees with that of chimpanzees in wet habitats, especially Mahale and Gombe in Tanzania, in the literature. Chimpanzees in Ugalla had eaten 117 plant parts of 100 plant species, 1 bird species, at least 1 small mammal species, and at least 3 insect species, including termites and ants. These chimpanzees in Ugalla ate fewer plant species and plant parts, more underground storage organs of plants, and fewer vertebrates and invertebrates than did the chimpanzees in Mahale and Gombe

Sleeping site selection by savanna chimpanzees in Ugalla, Tanzania

We examined sleeping site selection by chimpanzees (Pan troglodytes) in the Ugalla savanna woodland area, western Tanzania, from 1994 to 2012. We established 488 km of line transects and recorded 379 chimpanzee beds within 30 m perpendicular to the transects. Comparisons between 60 × 60 m2 quadrats containing new and recent beds and the remaining quadrats without beds along the transects indicated that evergreen forests accounted for disproportionately more area in quadrats with beds than in those without beds during both the dry and rainy seasons. In Ugalla, chimpanzees coexist with lions (Panthera leo) and leopards (Panthera pardus). They may sleep in forests to reduce predation risk by these carnivores, as trees are dense and the canopy is high and closed. The angle of slope was steeper in quadrats containing beds than in those without beds during the dry season, whereas the angle was less steep in quadrats with beds than in those without beds during the rainy season. Additionally, fewer beds were found further from forests. The distance between beds and forests during the dry season was shorter than that during the rainy season. Chimpanzees may sleep in or near forests and on slopes because of water pools in the valley forests along the slopes during the dry season. Quadrats with beds were at slightly higher altitude than those without beds during the rainy season; however, the difference was not significant during the dry season. The number of beds found in or close to feeding trees was not related to the fruiting period. Sleeping site selection by chimpanzees may be affected by predation pressure and water availability in the savanna woodland area