Observations are presented primarily from two study sites located in the extreme southwestern tip of the Central African Republic. The use of flexible stalks and rigid sticks to extract termites from mounds and pounding, prying, and digging tools to penetrate melipone, honey bee, and ground-dwelling bee hives by Pan t. troglodytes are documented or inferred from circumstantial evidence. Functionally, termite extraction tools were similar to other locations in west and central Africa, but the plant species used were considerably different. Extraction of bees using large pieces of wood as pounding tools has not been recorded elsewhere in wild chimpanzees. No environmental factor that differs between the east and west of the range of P. t. troglodytes that would cause the difference in tool use was identified. o

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Poaching of forest elephants (Loxodonta cyclotis) for ivory has decimated their populations in Central Africa. Studying elephant movement can provide insight into habitat and resource use to reveal where, when, and why they move and guide conservation efforts. We fitted 17 forest elephants with global positioning system (GPS) collars in 2015 and 2016 in the tropical forest-grassland mosaic of the Wonga Wongué Presidential Reserve (WW), Gabon. Using the location data, we quantified movement distances, home ranges, and habitat use to examine the environmental drivers of elephant movements and predict where elephants occur spatially and temporally. Forest elephants, on average, traveled 2,840 km annually and had home ranges of 713 km2, with males covering significantly larger home ranges than females. Forest elephants demonstrated both daily and seasonal movement patterns. Daily, they moved between forest and grassland at dawn and dusk. Seasonally, they spent proportionally more time in grassland than forest during the short-wet season when grasses recruit. Forest elephants also traveled faster during the short-wet season when fruit availability was greatest, likely reflecting long, direct movements to preferred fruiting tree species. Forest elephants tended to select areas with high tree and shrub density that afford cover and browse. When villages occurred in their home ranges elephants spent a disproportionate amount of time near them, particularly in the dry season, probably for access to agricultural crops and preferred habitat. Given the importance of the grassland habitat for elephants, maintenance of the forest-grassland matrix is a conservation priority in WW. Law enforcement, outreach, and education should focus on areas of potential human-elephant conflict near villages along the borders of the reserve. GPS-tracking should be extended into multi-use areas in the peripheries of protected areas to evaluate the effects of human disturbance on elephant movements and to maintain connectivity among elephant populations in Gabon.

In June through August of 1986 I completed a census of the southern extreme of the gorilla range in the Central African Republic. Two 100 km 2 blocks (214.4 km of transects) of mostly primary forest along the Sangha River were surveyed. In the first block a total of 220 nests were counted and in the second 327. The average gorilla density for both blocks was calculated to be 1.6 gorillas per km 2 . The second block contained almost twice the density as the first with 2.0 gorillas/km 2 as opposed to 1.1 gorillas/km 2 . The average nest group size overall was 4.1 nests with the first block having a slightly larger average nest group size of 4.3 as opposed to 3.9 for the second block. The most common nest material was Megaphrynium marcrostachyum. The seeds of at least one of three important fruits eaten by gorillas were found in more than 65 % of the droppings analyzed, indicating a high level of frugivory in the wet season diet of western lowland gorillas. Nine other species of diurnal primates were also observed during the survey.R sum . -En juin-aoüt 1986 les populations de Gorilla gorilla gorilla ont ete recensees dans l'extreme sud-ouest de la Republique Centrafricaine. Le recensement a couvert deux parcelles de 100 km 2 , pour la plupart en foret primaire, avec un total de 214,4 km de transects. Dans la premiere parcelle, 220 nids ont ete recenses, et dans la deuxieme 327. La densite moyenne de gorilles pour les deux parcelles a ete calculee a 1,6 gorilles/km 2 , avec 1,1 gorilles/km 2 dans la premiere et 2,0 gorilles/km 2 dans la deuxieme. Le nombre moyen de nids d'un meme groupe a ete 4,1, avec 4,3 dans la premiere parcelle et 3,9 dans la deuxieme. La plupart des nids ont ete construits avec Megaphrynium macrostachyum (Marantacoes). Les graines d'un des trois fruits les plus couramment mangees par les gorilles de la region ont ete retrouvees dans plus de 65 % des dejections analysees, ce qui indique un taux de frugivorie tres eleve. Neuf autres especes de Primates diurnes ont etes observees pendant le recensement.

Large brains and behavioural innovation are positively correlated, species-specific traits, associated with the behavioural flexibility animals need for adapting to seasonal and unpredictable habitats. Similar ecological challenges would have been important drivers throughout human evolution. However, studies examining the influence of environmental variability on within-species behavioural diversity are lacking despite the critical assumption that population diversification precedes genetic divergence and speciation. Here, using a dataset of 144 wild chimpanzee (Pan troglodytes) communities, we show that chimpanzees exhibit greater behavioural diversity in environments with more variability — in both recent and historical timescales. Notably, distance from Pleistocene forest refugia is associated with the presence of a larger number of behavioural traits, including both tool and non-tool use behaviours. Since more than half of the behaviours investigated are also likely to be cultural, we suggest that environmental variability was a critical evolutionary force promoting the behavioural, as well as cultural diversification of great apes.

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We censused gorilla populations in northern Congo from February to April 1989 and June 1990. The objective was to provide the first quantitative data from a variety of sites on gorilla populations from a country that had unknown but potentially high populations. The method used was a census of nests along strip transects. A total of 401.0 km of transects was sampled in four different study areas. The overall density calculated for all transects was 0.4 nesting gorillas/km2. The highest density, 1.2 nesting gorillas/km2, was found in the vast Likouala swamp area of north central Congo. The two northern sites showed low densities of 0.1 and 0.2 nesting gorillas/km2, respectively. The northwestern site showed an intermediate density of 0.6 nesting gorillas/km2. The vegetation type with the highest density was swamp forest with 2.4 nesting gorillas/km2. The limited sample presented shows that gorillas are widespread and common in northern Congo, even in the swamp forests previously considered unsuitable as gorilla habitat. It is probable that Congo holds the largest population of gorillas in Africa after Gabon. © 1992 Wiley‐Liss, Inc.