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Roberts A.I.,University of Stirling | Roberts A.I.,University of Oxford | Vick S.-J.,University of Stirling | Roberts S.G.B.,University of Oxford | And 4 more authors.
Evolution and Human Behavior | Year: 2012

Great ape gestural communication is considered important in understanding the evolution of human language as these share important features, namely, flexible and intentional signal use. Although gestural repertoires have been compiled for captive and wild primates, reports are largely qualitative. We quantify the morphological structure and variation of gestural signals identified in the repertoire of a community of wild chimpanzees. Gestures were classified on the basis of 29 morphological features, such as trajectory and orientation during the preparatory and stroke phases of a gesture. Hierarchical cluster and discriminant function analyses identified 30 morphologically distinct manual gesture types; the majority was subsequently correctly classified using a cross-validation technique, with incorrect classifications for rare gesture types only. Comparisons of this statistically determined repertoire with previous repertoires did not identify systematic variation between captive and wild chimpanzees. Moreover, consensus was not greater within studies of the same populations, highlighting the importance of systematic and well-documented inventories. Our morphologically based analyses indicate that manual gestures are best considered as graded rather than discrete communication signals, similar to some vocalisation systems. We discuss these findings in light of current theories of human language evolution. © 2012 Elsevier Inc.


Murphy D.,University of Exeter | Murphy D.,University of Aberdeen | Lea S.E.G.,University of Exeter | Zuberbuhler K.,Budongo Conservation Field Station | And 2 more authors.
Animal Behaviour | Year: 2013

There is considerable controversy about what is encoded when primates produce alarm calls to an external event. Results are often compatible with multiple explanations, such as differences in a caller's perceived level of threat, direction of attack or category of predator. Using acoustic predator models, we investigated how male blue monkeys', Cercopithecus mitis stuhlmani, alarm calls were affected by predator type, distance, and elevation. We found that individuals produced two types of acoustically distinct alarm calls, 'pyows' and 'hacks'. Males produced these calls in predator-specific ways, but call rates were also affected by the distance and location of the predator. We discuss these findings in relation to the different predator hunting techniques and two common antipredator strategies pursued by monkeys, predator deterrence and conspecific warning. © 2012 The Association for the Study of Animal Behaviour.


Hobaiter C.,University of St. Andrews | Poisot T.,University of Quebec at Rimouski | Poisot T.,Quebec Center for Biodiversity science | Zuberbuhler K.,University of St. Andrews | And 4 more authors.
PLoS Biology | Year: 2014

Social network analysis methods have made it possible to test whether novel behaviors in animals spread through individual or social learning. To date, however, social network analysis of wild populations has been limited to static models that cannot precisely reflect the dynamics of learning, for instance, the impact of multiple observations across time. Here, we present a novel dynamic version of network analysis that is capable of capturing temporal aspects of acquisition—that is, how successive observations by an individual influence its acquisition of the novel behavior. We apply this model to studying the spread of two novel tool-use variants, “moss-sponging” and “leaf-sponge re-use,” in the Sonso chimpanzee community of Budongo Forest, Uganda. Chimpanzees are widely considered the most “cultural” of all animal species, with 39 behaviors suspected as socially acquired, most of them in the domain of tool-use. The cultural hypothesis is supported by experimental data from captive chimpanzees and a range of observational data. However, for wild groups, there is still no direct experimental evidence for social learning, nor has there been any direct observation of social diffusion of behavioral innovations. Here, we tested both a static and a dynamic network model and found strong evidence that diffusion patterns of moss-sponging, but not leaf-sponge re-use, were significantly better explained by social than individual learning. The most conservative estimate of social transmission accounted for 85% of observed events, with an estimated 15-fold increase in learning rate for each time a novice observed an informed individual moss-sponging. We conclude that group-specific behavioral variants in wild chimpanzees can be socially learned, adding to the evidence that this prerequisite for culture originated in a common ancestor of great apes and humans, long before the advent of modern humans. © 2014 Hobaiter et al.


McLennan M.R.,Oxford Brookes University | Hyeroba D.,Jane Goodall Institute | Asiimwe C.,Budongo Conservation Field Station | Reynolds V.,Budongo Conservation Field Station | Wallis J.,University of Oklahoma
ORYX | Year: 2012

Abstract A main concern of farmers worldwide is how to reduce crop losses to wildlife. Some potentially lethal crop protection methods are non-selective. It is important to understand the impact of such methods on species of conservation concern. Uganda has important populations of Endangered eastern chimpanzees Pan troglodytes schweinfurthii. Farmers sometimes use large metal mantraps to guard their fields against crop-raiding wildlife, particularly baboons Papio anubis and wild pigs Potamochoerus sp.. Chimpanzees that range onto farmland also step in these illegal devices and without rapid veterinary invention face severe injury or eventual death. Unlike inadvertent snaring of great apes in African forests, the problem of mantraps in forest-farm ecotones has received little attention. We report 10 cases of entrapped chimpanzees in the cultivated landscape surrounding Uganda's Budongo Forest during 2007-2011, undoubtedly only a portion of the actual number of cases. Mantraps currently present a substantial threat to ape populations in this important conservation landscape. Our data underscore the need for conservation programmes to consider the techniques used by rural farmers to protect their livelihoods from wild animals. © 2012 Fauna & Flora International.


McLennan M.R.,Oxford Brookes University | Asiimwe C.,Budongo Conservation Field Station
Primates | Year: 2016

Roads have broadly adverse impacts on wildlife, including nonhuman primates. One direct effect is mortality from collisions with vehicles. While highly undesirable, roadkills provide valuable information on the health and condition of endangered species. We present a case report of a wild chimpanzee (Pan troglodytes schweinfurthii) killed crossing a road in Bulindi, Uganda, where chimpanzees inhabit forest fragments amid farmland. Details of the collision are constructed from eyewitness accounts of pedestrians. Physical examination of the cadaver indicated good overall body condition; at 40 kg, the deceased female was heavier than usual for an adult female East African chimpanzee. No external wounds or fractures were noted. Coprological assessment demonstrated infection by several gastrointestinal parasites commonly reported in living wild chimpanzees. Histopathology revealed eosinophilic enteritis and biliary hyperplasia potentially caused by parasite infection. However, eosinophilia was not widely spread into the submucosa, while egg/cyst counts suggested low-intensity parasite infections compared to healthy female chimpanzees of similar age in nearby Budongo Forest. No behavioral indicators of ill health were noted in the deceased female in the month prior to the accident. We conclude that cause of death was acute, i.e., shock from the collision, and was probably unrelated to parasite infection or any other underlying health condition. Notably, this female had asymmetrical polythelia, and, while nursing at the time of her death, had one functioning mammary gland only. In Uganda, where primates often inhabit human-dominated landscapes, human population growth and economic development has given rise to increasing motor traffic, while road development is enabling motorists to travel at greater speeds. Thus, the danger of roads to apes and other wildlife is rising, necessitating urgent strategies to reduce risks. Installation of simple speed-bumps—common on Ugandan roads—would be effective in reducing risks to wildlife, and would also make roads safer for human pedestrians. © 2016 Japan Monkey Centre and Springer Japan


Slocombe K.E.,University of York | Kaller T.,University of York | Turman L.,Budongo Conservation Field Station | Townsend S.W.,University of Zürich | And 3 more authors.
Behavioral Ecology and Sociobiology | Year: 2010

Chimpanzees produce acoustically distinct calls when encountering food. Previous research on a number of species has indicated that food-associated calls are relatively widespread in animal communication, and the production of these calls can be influenced by both ecological and social factors. Here, we investigate the factors influencing the production of food-associated calls in wild chimpanzees and examine whether male chimpanzees produce food-associated calls selectively in the presence of important social partners. Male chimpanzees form stable long-term social relationships with each other, and these social bonds are vital in enabling a range of cooperative activities, such as group hunting and territory defence. Our data show that males were significantly more likely to produce food-associated calls if an important social partner was nearby, regardless of the size of the audience or the presence of oestrus females. Call production was also mediated by the size of the food patch and by whether or not the food could be monopolised. The presence of important social partners explained most of the variation in male calling behaviour, indicating that food-associated calls are socially directed and serve a bonding function. © 2010 Springer-Verlag.


Schel A.M.,University of York | Townsend S.W.,University of Zürich | Machanda Z.,Harvard University | Zuberbuhler K.,Budongo Conservation Field Station | And 3 more authors.
PLoS ONE | Year: 2013

Determining the intentionality of primate communication is critical to understanding the evolution of human language. Although intentional signalling has been claimed for some great ape gestural signals, comparable evidence is currently lacking for their vocal signals. We presented wild chimpanzees with a python model and found that two of three alarm call types exhibited characteristics previously used to argue for intentionality in gestural communication. These alarm calls were: (i) socially directed and given to the arrival of friends, (ii) associated with visual monitoring of the audience and gaze alternations, and (iii) goal directed, as calling only stopped when recipients were safe from the predator. Our results demonstrate that certain vocalisations of our closest living relatives qualify as intentional signals, in a directly comparable way to many great ape gestures. We conclude that our results undermine a central argument of gestural theories of language evolution and instead support a multimodal origin of human language. © 2013 Schel et al.


Schel A.M.,University of York | Machanda Z.,Harvard University | Townsend S.W.,University of Zürich | Zuberbuhler K.,Budongo Conservation Field Station | And 3 more authors.
Animal Behaviour | Year: 2013

If primates were capable of vocalizing to inform a receiver about an external entity, it would represent an important element of continuity with human language. We tested experimentally whether chimpanzee rough grunts, which function to refer to food, are produced selectively, indicating voluntary control, and whether they are directed at specific individuals. These are prerequisites for a system capable of actively informing others about external events. We conducted a field playback experiment in which we presented silently feeding male chimpanzees, Pan troglodytes, with arrival pant hoots of a familiar group member. We found that subjects were significantly more likely to respond with food calls to the simulated arrival of an individual with whom the caller had a high rather than low level of friendship and where there was a large rather than small positive dominance rank difference between the individuals (i.e. caller was lower ranking). We concluded that chimpanzee food calls are not simply reflexive responses to food, but can be selectively directed at socially important individuals. Our findings are thus inconsistent with traditional views of primate vocalizations as inflexibly and indiscriminately produced. Instead, our results indicate that great apes can produce semantically meaningful calls in a highly selective, recipient-directed manner. Further research is needed to test whether chimpanzees use this flexible system to inform ignorant individuals about food, but the prerequisites to support this type of communication seem to be present. © 2013 The Association for the Study of Animal Behaviour.


Babweteera F.,Budongo Conservation Field Station | Brown N.,University of Oxford
Journal of Tropical Ecology | Year: 2010

The direct removal of adult trees by logging affects tree recruitment in tropical rain forests. However, secondary effects of logging, such as loss of vertebrate seed dispersers may also affect tree recruitment. We studied the recruitment and spatial distribution of five tree species namely Balanites wilsoniana, Celtis zenkeri, Chrysophyllum albidum, Cordia millenii and Ricinodendron heudelotii in Kibale, Budongo and Mabira Forests in Uganda. These forests have been subjected to varying degrees of disturbance leading to changes in their vertebrate seed dispersers. Vertebrate frugivores of the five tree species were identified. Three 1-ha plots were established around adult trees of the same five species in each forest and the distance from the juveniles to the nearest adult conspecific was measured to generate a recruitment curve. Frugivore visitation rates were high in the less disturbed Budongo and Kibale (2.2 and 1.6 individuals h-1 respectively) compared with the highly disturbed Mabira (0.9 individuals h-1). In the frugivore-impoverished forest, 70-90% of juveniles established beneath adult conspecifics, whereas in the less-disturbed forests juveniles were established up to 80 m from adult conspecifics. Shade-tolerant species capable of recruiting beneath adult conspecifics appeared to maintain their populations without dispersal. Consequently, disturbances leading to significant loss of vertebrates may alter tree recruitment and spatial distribution with consequences for long-term population viability of shade-intolerant tropical trees. Copyright © 2010 Cambridge University Press.


PubMed | Budongo Conservation Field Station
Type: Journal Article | Journal: Primates; journal of primatology | Year: 2016

The use of stick- or probe-tools is a chimpanzee universal, recorded in all long-term study populations across Africa, except one: Budongo, Uganda. Here, after 25 years of observation, stick-tool use remains absent under both natural circumstances and strong experimental scaffolding. Instead, the chimpanzees employ a rich repertoire of leaf-tools for a variety of dietary and hygiene tasks. One use of stick-tools in other communities is in feeding on the aggressive Dorylus army ant species, consumed by chimpanzees at all long-term study sites outside of mid-Western Uganda. Here we report the first observation of army-ant feeding in Budongo, in which individuals from the Waibira chimpanzee community employed detached leaves to feed on a ground swarm. We describe the behaviour and discuss whether or not it can be considered tool use, together with its implication for the absence of stick-tool culture in Budongo chimpanzees.

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