Behavior Of Chimpanzees Research Articles

Long-Term Evaluation of Abnormal Behavior in Adult Ex-laboratory Chimpanzees (Pan troglodytes) Following Re-socialization.

Adverse rearing conditions are considered a major factor in the development of abnormal behavior. We investigated the overall levels, the prevalence and the diversity of abnormal behavior of 18 adult former laboratory chimpanzees, who spent about 20 years single caged, over a two-year period following re-socialization. According to the onset of deprivation, the individuals were classified as early deprived (EDs, mean: 1.2 years) or late deprived (LDs, mean: 3.6 years). The results are based on 187.5 hours of scan sampling distributed over three sample periods: subsequent to re-socialization and during the first and second year of group-living. While the overall levels and the diversity of abnormal behavior remained stable over time in this study population, the amplifying effects of age at onset of deprivation became apparent as the overall levels of abnormal behavior of EDs were far above those of LDs in the first and second year of group-living, but not immediately after re-socialization. The most prevalent abnormal behaviors, including eating disorders and self-directed behaviors, however, varied in their occurrence within subjects across the periods. Most important, the significance of social companionship became obvious as the most severe forms of abnormal behavior, such as dissociative and self-injurious behaviors declined.

Attempted Predation by Nigeria-Cameroon Chimpanzees (Pan troglodytes ellioti) on Preuss’s Red Colobus (Procolobus preussi) in the Ebo Forest, Cameroon

We describe the first observation of a predation attempt by Nigerian-Cameroon chimpanzees (Pan troglodytes ellioti) on Preuss’s red colobus (Procolobus preussi) in the Ebo forest, Cameroon. The activity, which was observed for 15 min, primarily involved 1 chimpanzee and 1 red colobus individual, with a further 2 chimpanzees observing the event. Although the behaviour was interrupted when we were detected by the chimpanzees, we believe that this is the first recorded observation of hunting behaviour in Nigeria-Cameroon chimpanzees.

Stereotypical behaviors in chimpanzees rescued from the african bushmeat and pet trade.

Many orphaned chimpanzees whose mothers are illegally killed for their meat (bushmeat) in Africa are sold as pets or kept caged at hotels and businesses to attract tourists. As a result of being separated from their mothers and other chimpanzees at an early age, and spending years in impoverished captive conditions, some of these individuals engage in abnormal behaviors, including stereotypically scratching at their flesh and repetitively rocking back and forth. This paper presents case studies of Poco and Safari, two chimpanzees who were rescued by sanctuaries after living alone on display for humans at businesses for the first 7 to 8 years of their lives. Decades after their rescue, they still engage in stereotypical behaviors as a result of the psychological and physical trauma they endured early on. This paper combines data from in depth interviews with caregivers and direct observations of abnormal behaviors to assess psychological distress in captive-living chimpanzees. Our results highlight some lesser known harms of the bushmeat trade and the detrimental life-long consequences that keeping chimpanzees as “pets” can have on their mental health.

Ranging behavior of Mahale chimpanzees: a 16 year study

We have analyzed the ranging patterns of the Mimikire group (M group) of chimpanzees in the Mahale Mountains National Park, Tanzania. During 16years, the chimpanzees moved over a total area of 25.2 or 27.4km(2), as estimated by the grid-cell or minimum convex polygon (MCP) methods, respectively. Annually, the M group used an average of 18.4km(2), or approximately 70%, of the total home-range area. The chimpanzees had used 80% of their total home range after 5years and 95% after 11years. M group chimpanzees were observed more than half of the time in areas that composed only 15% of their total home range. Thus, they typically moved over limited areas, visiting other parts of their range only occasionally. On average, the chimpanzees used 7.6km(2) (in MCP) per month. Mean monthly range size was smallest at the end of the rainy season and largest at the end of the dry season, but there was much variability from year to year. The chimpanzees used many of the same areas every year when Saba comorensis fruits were abundant between August and January. In contrast, the chimpanzees used several different areas of their range in June. Here range overlap between years was relatively small. Over the 16years of the study we found that the M group reduced their use of the northern part of their range and increased their frequency of visits to the eastern mountainous side of their home range. Changes in home-range size correlated positively with the number of adult females but not with the number of adult males. This finding does not support a prediction of the male-defended territory model proposed for some East African chimpanzee unit-groups.

Ontogeny of a Social Custom in Wild Chimpanzees: Age Changes in Grooming Hand‐Clasp at Mahale

Among cultural behaviors of chimpanzees, the developmental processes of complex skills involved in tool use are relatively well known. However, few studies have examined the ontogeny of social customs that do not require complex skills. Thus, in this study, we describe the developmental process of the grooming hand-clasp (GHC), one of the well-known social customs of chimpanzees at Mahale. We have collected 383 cases of GHC where at least one of the participants was 15 years old or younger during 1994-2007. First performances of GHC with the mother were observed at around 4-6 years old; the earliest observed age was 4 years and 4 months old. The first performances of GHC with nonrelated females were at around age 9 years, and those with adult males at around 11 years. However, some orphans engaged in GHC earlier than nonorphans. By gradually expanding GHC partners from the mother to other females and then to males, chimpanzees increased the number of GHC partners with age. Young males were observed to perform GHC with larger numbers of partners than were young females. GHC by young chimpanzees was shorter in duration than that among adults. Overall, the ontogeny of GHC showed several dissimilarities with that of tool use and was more an extension of the development of typical grooming behavior. For example, infants did not try to perform GHC initially; instead, mothers were more active in the earliest stages. These results suggest that not all socially learned cultural behaviors are acquired in the way of learning tool use. There may be various ways of learning behavioral patterns that are performed continuously in a group and that consequently comprise culture in chimpanzees.

Games primates play: an undercover investigation of the evolution and economics of human relationships

Most humans don't realize that when they exchange emails with someone, anyone, they are actually exhibiting certain unspoken rules about dominance and hierarchy. The same rules regulate the exchange of grooming behavior in rhesus macaques or chimpanzees. Interestingly, some of the major aspects of human nature have profound commonalities with our ape ancestors: the violence of war, the intensity of love, the need to live together. While we often assume that our behavior in everyday situations reflects our unique personalities, the choices we freely make, or the influences of our environment, we rarely consider that others behave in these situations in almost the exact the same way as we do. In Games Primates Play, primatologist Dario Maestripieri examines the curious unspoken customs that govern our behavior. These patterns and customs appear to be motivated by free will, yet they are so similar from person to person, and across species, that they reveal much more than our selected choices. Games Primates Play uncovers our evolutionary legacy: the subtle codes that govern our behavior are the result of millions of years of evolution, predating the emergence of modern humans. To understand the rules that govern primate games and our social interactions, Maestripieri arms readers with knowledge of the scientific principles that ethologists, psychologists, economists, and other behavioral scientists have discovered in their quest to unravel the complexities of behavior. As he realizes, everything from how we write emails to how we make love is determined by the legacy of our primate roots and the conditions that existed so long ago. An idiosyncratic and witty approach to our deep and complex origins, Games Primates Play reveals the ways in which our primate nature drives so much of our lives.

On the state of nature and social life: thinking about humans and chimpanzees1

The anatomical similarity observed in chimpanzees and humans has been recognized since Linnaeus. The debates on the attribution of the human condition to non-Western people date back to the 15th century. However, only in the 20th century did Social and Cultural Anthropology demonstrate through ethnography that the Enlightenment project of defining an universal and unique humankind has a consistent and real face as a result of research and reformulation of ideas. Only since the 1960s has the cumulative knowledge on wild chimpanzee behavior informed us about their ability to produce and use tools, for social learning, and to produce unique patterns of collective behavior. Ever since, primatological and human evolutionary research has contributed to an understanding of a surprising and uncomfortable similarity of human and non-human behaviors as well as to their deep differences. The practice of studying similarities and differences lead us to the same dead end: nature (on the genetic, biological and ecological level) is highly influential in determining that chimpanzees and humans live as social or sociocultural beings. Furthermore, considering these discoveries we need to reflect on the new meanings and the new places of nature in our knowledge when considering the social life of chimpanzees and humans. Taking into account how the influence of nature is deeply associated with the way of life of chimpanzees and humans, we must ask to what extent nature influences the social or cultural processes and to what extent they are autonomous. Even though considering my previous propositions that only humans produce culture, which is an essentially symbolic phenomenon, wild chimpanzees also have an intense and complex social life. In other words, this text proposes reflecting on the degrees of autonomy of social and cultural phenomena in relation to chimpanzee and human evolutionary predisposition to social life and to symbolic production as well as on the adaptive and non-adaptive aspects of these phenomena. This analysis adopted Rousseau's theory on the “State of Nature” and “State of Society” considering modern primatology from an anthropological point of view resulting in the invention of two concepts: “nature social primate” “primate social nature” and “human cultural nature”.

Anxiety-related behavior of orphan chimpanzees (Pan troglodytes schweinfurthii) at Gombe National Park, Tanzania

This study examined the anxiety levels and social interactions of two orphan and four mother-reared adolescent chimpanzees (Pan troglodytes schweinfurthii) in the Kasekela community at Gombe National Park, Tanzania. We used focal sampling in the field at Gombe to observe these adolescent individuals. Their social interactions and anxious behavior, measured as rough scratching, were recorded. The two orphans differed from others of a similar age by exhibiting higher levels of anxiety and lower levels of play. These results suggest that a mother's absence, even in naturalistic conditions in which other members of the community are available to the orphan, may have long-lasting impact on an adolescent's anxiety and its ability to engage in complex social interactions, such as play.

Cultura e inteligência: reflexões antropológicas sobre aspectos não físicos da evolução em chimpanzés e humanos

The scope of this work is the recent history of studies on the behavior of chimpanzees, emphasizing research results, propositions about the existence of 'chimpanzee cultures' and their validity. The work discusses the idea based on transmission mechanisms and social learning as well as anthropological and paleoanthropological concepts of culture that associate such phenomena, among modern humans, to their symbolic and cognitive abilities.

Hunting Activity Among Naturalistically Housed Chimpanzees (Pan troglodytes) at the Fundació Mona (Girona, Spain). Predation, Occasional Consumption and Strategies in Rehabilitated Animals

Simple Summary:Hunting is well documented in wild chimpanzees, but has rarely been documented in captive chimpanzees. At Fundació Mona Primate Rescue we have obtained evidence of five episodes of hunting in rehabilitated chimpanzees who had no previous experience of these types of behaviors. This demonstrated that they were able to perform this species-typical behavior in a naturalistic environment without learning it in the wild.:Predatory behavior in wild chimpanzees and other primates has been well documented over the last 30 years. However, as it is an opportunistic behavior, conditions which may promote such behavior are left up to chance. Until now, predatory behavior among captive chimpanzees has been poorly documented. In this paper, we present five instances providing evidence of predatory behavior: four performed by isolated individuals and one carried out in cooperation. The evidence of group predation involved the chimpanzees adopting different roles as pursuers and ambushers. Prey was partially eaten in some cases, but not in the social episode. This study confirms that naturalistic environments allow chimpanzees to enhance species-typical behavioral patterns.

Behavioral correlates and welfare implications of informal interactions between caretakers and zoo-housed chimpanzees and gorillas

In captive animal facilities, human staff members are a relevant part of the animals’ social environment in addition to providing care and managing the social group. Structured, predictable interactions and relaxed, spontaneous contacts may all affect the animals’ behavior and well-being, both immediately and in the long term. This study examined the association between unstructured, affiliative caretaker–animal interactions and the behavior of zoo-housed chimpanzees (Pan troglodytes) and Western lowland gorillas (Gorilla gorilla gorilla). The interactions in question included play, spontaneous feeding, and other positive vocal and visual interactions performed through a protective mesh barrier. Behavioral data collected over 48 months were used to identify correlates of caretaker interactions among key behaviors relevant to welfare assessment, including agonism, sexual behavior, abnormal behavior, prosocial behavior, and self-directed behavior, as well as the presence of wounds. In observational sessions containing one or more caretaker interactions, chimpanzees and gorillas both showed higher agonism (P=0.044 and P=0.042, respectively) and lower self-directed behavior (P=0.035 for chimpanzees and P=0.001 for gorillas) than in control samples. Agonism rose in chimpanzees from an average of 0.01–0.12% of overall behaviors, and in gorillas from 0% to 0.1%, while self-directed behavior decreased in chimpanzees from an average of 9.54–7.81% and in gorillas from 11.02% to 7.38%. Chimpanzees also showed lower intraspecific prosocial behavior in samples with caretaker interactions (P=0.044), decreasing from an average of 11.5% to 5.52% of overall behaviors. Finally, gorillas exhibited less abnormal behavior in caretaker interaction samples than in control samples (P=0.029), decreasing from a mean of 2.42–1.77% of overall behaviors. In chimpanzees, higher agonism and lower prosocial behavior are indicative of greater arousal, although we would expect self-directed behavior to rise rather than decrease in that situation. The results in gorillas are mixed with respect to welfare outcomes: higher agonism is indicative of arousal, but lower abnormal and self-directed behaviors suggest a decrease in stress and anxiety. These findings underscore the importance of understanding the influence of all forms of interaction with heterospecifics and demonstrate a need for welfare assessments that include even positively intended interactions.

Environmental Influences on Sleep Behavior in Captive Male Chimpanzees (Pan troglodytes)

Little is known as to the influence of captivity and stressful events on sleep patterns in primates. We investigated the sleep patterns of 19 male chimpanzees living under similar conditions at the Chimpanzee Sanctuary Uto (CSU) in Kumamoto, Japan, using a behavioral sleep index. We conducted nighttime observations of all subjects during a stable period and then observed three subjects after relocation to an unfamiliar facility at CSU. We estimated length of sleep and nonsleep periods over 13-h video recordings using instantaneous sampling at 1-min intervals to record sleep, which we defined operationally as an inactive posture with the body lying down with the head on the floor or on nesting materials. The 19 subjects slept for a mean ± SEM of 11.3 ± 0.26 h during the stable period, and sleep patterns varied significantly among the subjects. The three relocated subjects all showed temporarily decreased sleep duration in the post-move period but subsequently recovered to the levels observed during the stable period when habituated to the new living quarters. These results suggest that a stressful event may induce temporary sleep shortage lasting for >1 wk in captive chimpanzees. Sleep patterns may serve as a useful behavioral index of the stress response, as it is less confounded by other behaviors and the actions of human caretakers than other indices.

Reactions of Bili‐Uele Chimpanzees to Humans in Relation to Their Distance From Roads and Villages

In order to assess the impact of human activities on chimpanzee behavior, we compared reactions to humans of Eastern chimpanzees (Pan troglodytes schweinfurthii) living in proximity to and at a distance from roads and settlements in the Bili-Uele landscape in Northern Democratic Republic of the Congo (DRC). We found that chimpanzees in the remote Gangu Forest were more likely to show curious or neutral reactions to us and were less likely to flee than those living closer to roads. In addition, arboreal contact durations with Gangu chimpanzees lasted significantly longer than elsewhere. The most likely explanation for this phenomenon is that with increasing distance from roads, chimpanzees have in the recent past had fewer negative encounters with humans, and thus never learned to fear them. The discovery of this population of "naïve chimpanzees" presents us with an important research and conservation opportunity that may result in the installation of a long-term research site and increased protection of the population.

Troublesome neighbours: Changing attitudes towards chimpanzees (Pan troglodytes) in a human-dominated landscape in Uganda

Long-term human–wildlife sympatry depends on the willingness and capacity of local people to coexist with wild animals. With human population growth and deforestation for agriculture, farmers increasingly live in proximity to wildlife, including large mammals of conservation concern. Understanding local perspectives and concerns regarding wildlife is essential for informing appropriate management strategies that reduce conflicts and promote sustainable coexistence. Social science approaches therefore have a critical role in integrated conservation programmes. We undertook an attitude survey to understand residents’ perspectives about sharing a landscape with chimpanzees (Pan troglodytes) in an unprotected forest–agriculture mosaic in Uganda. Interviews (n=134) in 12 villages demonstrate residents’ ambivalence towards living alongside these protected yet potentially troublesome mammals. Chimpanzee behaviour is reported to have undergone recent changes. Residents claim apes increasingly enter villages for food, threaten people, and pose a particular threat to children's safety. Chimpanzee numbers are believed to have increased locally. Most interviewees fear chimpanzees, considering them dangerous. Crop losses to chimpanzees were widely reported. Farmers tolerate raiding of domestic fruits, but not cash-crops. Results demonstrate that attitudes towards wildlife are not fixed. Reported changes to chimpanzee behaviour are challenging villagers’ traditionally benign attitude towards them. Even so, residents acknowledge benefits to chimpanzees because they reportedly displace other crop-raiding wildlife which, unlike chimpanzees, damage important staple food crops. Survey findings are contextualised with respect to recent, major land-use changes in Uganda (clearance of unprotected forest for timber and agriculture) that have precipitated a sharp rise in farmer–chimpanzee interactions. We discuss the study's broader implications for protected mammal management and conflict mitigation in human-dominated landscapes, and ask whether it is appropriate to expect impoverished rural farmers to accommodate large-bodied mammals that pose a potential threat to their safety and livelihoods.

The ontogeny of human prosociality: behavioral experiments with children aged 3 to 8

Humans regularly engage in prosocial behavior that differs strikingly from that of even our closest living relatives, the chimpanzees (Pan troglodytes). In laboratory settings, chimpanzees are indifferent when given the opportunity to deliver valued rewards to conspecifics, while even very young human children have repeatedly been shown to behave prosocially. Although this broadly suggests that prosocial behavior in chimpanzees differs from that of young human children, the methods used in prior work with children have also differed from the methods used in studies of chimpanzees in potentially crucial ways. Here we test 92 pairs of 3–8-year-old children from urban American (Los Angeles, CA, USA) schools in a face-to-face task that closely parallels tasks used previously with chimpanzees. We found that children were more prosocial than chimpanzees have previously been in similar tasks, and our results suggest that this was driven more by a desire to provide benefits to others than a preference for egalitarian outcomes. We did not find consistent evidence that older children were more prosocial than younger children, implying that younger children behaved more prosocially in the current study than in previous studies in which participants were fully anonymous. These findings strongly suggest that humans are more prosocial than chimpanzees from an early age and that anonymity influences children's prosocial behavior, particularly at the youngest ages.

Does geography or ecology best explain ‘cultural’ variation among chimpanzee communities?

Much attention has been paid to geographic variation in chimpanzee behavior, but few studies have applied quantitative techniques to explain this variation. Here, we apply methods typically utilized in macroecology to explain variation in the putative cultural traits of chimpanzees. We analyzed published data containing 39 behavioral traits from nine chimpanzee communities. We used a canonical correspondence analysis to examine the relative importance of environmental characteristics and geography, which may be a proxy for inter-community gene flow and/or social transmission, for explaining geographic variation in chimpanzee behavior. We found that geography, and longitude in particular, was the best predictor of behavioral variation. Chimpanzee communities in close longitudinal proximity to each other exhibit similar behavioral repertoires, independent of local ecological factors. No ecological variables were significantly related to behavioral variation. These results support the idea that inter-community dispersal patterns have played a major role in structuring behavioral variation. We cannot be certain whether behavioral variation has a genetic basis, is the result of innovation and diffusion, or a combination of the two.

Use of “Entertainment” Chimpanzees in Commercials Distorts Public Perception Regarding Their Conservation Status

Chimpanzees (Pan troglodytes) are often used in movies, commercials and print advertisements with the intention of eliciting a humorous response from audiences. The portrayal of chimpanzees in unnatural, human-like situations may have a negative effect on the public's understanding of their endangered status in the wild while making them appear as suitable pets. Alternatively, media content that elicits a positive emotional response toward chimpanzees may increase the public's commitment to chimpanzee conservation. To test these competing hypotheses, participants (n = 165) watched a series of commercials in an experiment framed as a marketing study. Imbedded within the same series of commercials was one of three chimpanzee videos. Participants either watched 1) a chimpanzee conservation commercial, 2) commercials containing “entertainment” chimpanzees or 3) control footage of the natural behavior of wild chimpanzees. Results from a post-viewing questionnaire reveal that participants who watched the conservation message understood that chimpanzees were endangered and unsuitable as pets at higher levels than those viewing the control footage. Meanwhile participants watching commercials with entertainment chimpanzees showed a decrease in understanding relative to those watching the control footage. In addition, when participants were given the opportunity to donate part of their earnings from the experiment to a conservation charity, donations were least frequent in the group watching commercials with entertainment chimpanzees. Control questions show that participants did not detect the purpose of the study. These results firmly support the hypothesis that use of entertainment chimpanzees in the popular media negatively distorts the public's perception and hinders chimpanzee conservation efforts.

The development of a greeting signal in wild chimpanzees

Adult chimpanzees produce a unique vocal signal, the pant-grunt, when encountering higher-ranking group members. The behaviour is typically directed to a specific receiver and has thus been interpreted as a 'greeting' signal. The alpha male obtains a large share of these calls, followed by the other adult males of the group. In this study, we describe the development of pant-grunting behaviour from the first grunt-like calls of newborn babies to the fully developed pant-grunts in adults. Although babies produce grunts from very early on, they are not directed to others until about 2 months of age. Subsequently, socially directed grunting steadily increases in frequency to peak around 7 months of age, but then decreases again to reach a nadir in older infants and juveniles, while the specificity in use increases. During adolescence, grunt production increases again with grunts given most frequently to socially relevant individuals. As young chimpanzees are closely affiliated to their mothers for the first decade of their lives, we also compared the grunting patterns of mothers and their offspring, which revealed some influences in pant-grunt production. In conclusion, the acquisition of pant-grunting behaviour in chimpanzees is a long-lasting process with distinct developmental phases in which social influences by the mother and other group members are likely to play a role.

How abnormal is the behaviour of captive, zoo-living chimpanzees?

BackgroundMany captive chimpanzees (Pan troglodytes) show a variety of serious behavioural abnormalities, some of which have been considered as possible signs of compromised mental health. The provision of environmental enrichments aimed at reducing the performance of abnormal behaviours is increasing the norm, with the housing of individuals in (semi-)natural social groups thought to be the most successful of these. Only a few quantitative studies of abnormal behaviour have been conducted, however, particularly for the captive population held in zoological collections. Consequently, a clear picture of the level of abnormal behaviour in zoo-living chimpanzees is lacking.MethodsWe present preliminary findings from a detailed observational study of the behaviour of 40 socially-housed zoo-living chimpanzees from six collections in the United States of America and the United Kingdom. We determined the prevalence, diversity, frequency, and duration of abnormal behaviour from 1200 hours of continuous behavioural data collected by focal animal sampling.Results, Conclusion and SignificanceOur overall finding was that abnormal behaviour was present in all sampled individuals across six independent groups of zoo-living chimpanzees, despite the differences between these groups in size, composition, housing, etc. We found substantial variation between individuals in the frequency and duration of abnormal behaviour, but all individuals engaged in at least some abnormal behaviour and variation across individuals could not be explained by sex, age, rearing history or background (defined as prior housing conditions). Our data support a conclusion that, while most behaviour of zoo-living chimpanzees is ‘normal’ in that it is typical of their wild counterparts, abnormal behaviour is endemic in this population despite enrichment efforts. We suggest there is an urgent need to understand how the chimpanzee mind copes with captivity, an issue with both scientific and welfare implications.

SUBMISSIVE PANT-GRUNT GREETING OF FEMALE CHIMPANZEES IN MAHALE MOUNTAINS NATIONAL PARK, TANZANIA

One of the unique greeting behaviors of chimpanzees (Pan troglodytes ( ) is pant- grunt vocalization, which is given only by lower-ranking individuals toward a more dominant group member. It is a typical social behavior performed when adult females encounter adult males. Previous studies have proposed some social functions of pant-grunts, such as signaling submission, signaling appeasement, expressing support, and checking tolerance. To evaluate the social variables driving pant-grunts, I investigated pant-grunts by adult female chimpan- zees of the M group in Mahale Mountains National Park, Tanzania. I found that pant-grunts functioned as a submissive signal between adult males and females, but did not always occur during encounters of adult females with adult males. Whether the pant-grunt functions as an appeasement signal remains unclear, but adult females performed pant-grunts as a reaction to the aggression of other individuals. Adult females did not express their support for a particular male by pant-grunting during the study period, probably because the dominance rank among adult males was stable. Rather than checking tolerance at the time, maintaining relations with adult males by pant-grunting was more essential for adult females. Whether adult females performed pant-grunts during encounters with adult males depended on the individuals present, the social power balance, and the current social interactions.