Captive Chimpanzees Research Articles

Surgical Management of Left-Hand Traumatic Injury in an Adult Female Captive Chimpanzee (Pan troglodytes): A Case Report

Captive chimpanzees are reported to present a higher frequency of injuries compared to those obtained in the wild due to their intraspecific aggression. Wounds are inescapable events in life following physical, chemical, thermal, microbial, or immunological insult to a body tissue, resulting in disruptions, breakage and loss of cellular and anatomical or functional continuity of living tissues or organs. The attention of the Veterinary Teaching Hospital, University of Jos was drawn to an injured adult female chimpanzee at the Jos Zoo. History revealed that the wound was the result of aggression from a counterpart chimpanzee. History reveals also that the wound was managed for 1 month before presentation with no significant improvement. Close examination revealed degloved left index and ring digits with pussy discharges. Assessment of the wound was undertaken after chemical immobilization and the resulting defects were reconstructed following proper aseptic surgical preparation utilizing chlorhexidine gluconate (Purit®) and amputation of the non-viable segments of the affected digits. Postoperatively, daily cleaning and administration of oxytetracycline spray (topical), doxycycline capsules 5 mg/kg ϰ1/52 PO and Dolometa B® ϰ5/7 PO were instituted. This case demonstrated the important role of prompt and thorough clinical evaluation in the adoption of management options, especially in wildlife management.

Increased alertness and moderate ingroup cohesion in bonobos' response to outgroup cues.

In a number of species, including humans, perceived outgroup threat can promote ingroup cohesion. However, the distribution and selection history of this association across species with varied intergroup relations remains unclear. Using a sample of 8 captive groups (N = 43 individuals), we here tested whether bonobos, like chimpanzees, show more affiliative ingroup behaviour following perception of outgroup cues (unfamiliar male long-distance vocalisations). We used comparable methods to our previous study of captive chimpanzees, and found that, although weaker, there was an association for more frequent social grooming in response to the outgroup condition than the control condition, alongside more alert posture and increased self-directed behaviour. This provides preliminary evidence for an ancestral origin to the proximate association between outgroup cues and ingroup cohesion, at least prior to the Pan-Homo split, and suggests the presence of intergroup competition in our last common ancestor.

Age-related physiological dysregulation progresses slowly in semi-free-ranging chimpanzees.

Lifestyle has widespread effects on human health and aging. Prior results from chimpanzees (Pan troglodytes), one of humans' closest evolutionary relatives, indicate that these lifestyle effects may also be shared with other species, as semi-free-ranging chimpanzees fed a naturalistic diet show healthier values in several specific health biomarkers, compared with their sedentary, captive counterparts. Here, we examined how lifestyle factors associated with different environments affect rates of physiological aging in closely related chimpanzees. We compared physiological dysregulation, an index of biological aging, in semi-free-ranging chimpanzees in an African sanctuary versus captive chimpanzees in US laboratories. If the rate of aging is accelerated by high-calorie diet and sedentism, we predicted greater age-related dysregulation in the laboratory populations. Conversely, if costs of a wild lifestyle accelerate aging, then semi-free-ranging chimpanzees at the sanctuary, whose environment better approximates the wild, should show greater age-related dysregulation. We further tested whether dysregulation differed based on sex or body system, as in humans. We found that semi-free-ranging chimpanzees showed lower overall dysregulation, as well as lower age-related change in dysregulation, than laboratory chimpanzees. Males experienced lower dysregulation than females in both contexts, and the two populations exhibited distinct aging patterns based on body system. Our results support the conclusion that naturalistic living conditions result in healthier aging in chimpanzees. These data provide support for the proposal that lifestyle effects on human health and aging are conserved from deeper into our evolutionary history.

Neighbors, Pros and Cons: Impact of Intergroup Interactions on the Welfare of Captive Chimpanzee Groups (Pan troglodytes)

Housing different animal groups in close-by facilities is common in wildlife centers. However, the impact on animal welfare is insufficiently studied in the literature. In this study, we analyzed the behavior of two adjacently housed chimpanzee groups to investigate how intergroup interactions may affect their behavior and, thus, their welfare. We recorded occurrences of abnormal and self-directed behaviors, two well-known indicators of stress in chimpanzees. Furthermore, we explored the social responses to said intergroup interactions by recording all inter- and intragroup affiliative and agonistic behaviors. Finally, we measured the number of vigilance occurrences that individuals directed towards other chimpanzees as an indicator of interest. Generalized Linear Mixed Models (GLMMs) were used to assess whether and how social interactions between neighboring groups might influence their behaviors, taking gender, age, group, and intergroup participation into account. Our results suggest that intergroup interactions promoted the occurrence of affiliative behaviors between group members. However, intergroup interactions caused the chimpanzees to exhibit a higher number of abnormal and self-directed behaviors and increased vigilance towards their group members when agonistic intergroup interactions occurred. Thus, adjacent housing does impact the chimpanzees’ behavior and welfare and should be continuously monitored and assessed to promote and maximize welfare.

Measuring heart rate in captive chimpanzees without anesthesia.

Heart rate measurements can be useful for the monitoring of both physical and mental condition in humans and nonhuman animals. Yet, information about heart rates in chimpanzees, who are phylogenetically the closest species to humans, is scarce. Existing data on chimpanzee heart rates have mainly been collected from chimpanzees under anesthesia. To address this issue, we conducted electrocardiogram recordings in captive chimpanzees under normal conditions without anesthesia based on positive reinforcement training. We obtained a total of 771 recordings from 35 individuals (22 males and 13 females, 14-53years old) with no cardiac problems. The females had a higher heart rate than the male chimpanzees, and heart rate decreased as a function of age. In addition, heart rate was lower in the morning and increased during the day. Overall, the mean heart rate of adult males was 86.5 beats/min, and that of female chimpanzees 106.4 beats/min. Our data could serve as a reference point for future research and health-based monitoring of chimpanzee heart rates.

Propofol partial intravenous anaesthesia with isoflurane alone or in combination with fentanyl and ketamine infusions in three captive chimpanzees (Pan troglodytes) undergoing different diagnostic and surgical procedures

AbstractThree captive chimpanzees (Pan troglodytes) were scheduled for diagnostic and surgical procedures under general anaesthesia. After premedication with oral midazolam (0.2 mg kg−1) and intramuscular medetomidine (20 µg kg−1) and ketamine (3 mg kg−1), anaesthesia was induced with intravenous propofol (1–4 mg kg−1). The animals were then maintained under general anaesthesia with propofol partial intravenous anaesthesia (0.10–0.17 mg kg−1 min−1) and isoflurane. On four occasions, the anaesthetised animals received fentanyl (1–3 µg kg−1 h−1) and ketamine (5–10 µg kg−1 min−1) infusions for analgesia. All animals recovered uneventfully. This case series details the anaesthetic protocols used, the challenges presented to the anaesthetist by this species and the peri‐anaesthetic complications observed. It also introduces the use of propofol total intravenous anaesthesia as an option for safe transportation of captive chimpanzees between facilities.

Maxillary morphology of chimpanzees: Captive versus wild environments.

Morphological studies typically avoid using osteological samples that derive from captive animals because it is assumed that their morphology is not representative of wild populations. Rearing environments indeed differ between wild and captive individuals. For example, mechanical properties of the diets provided to captive animals can be drastically different from the food present in their natural habitats, which could impact cranial morphology and dental health. Here, we examine morphological differences in the maxillae of wild versus captive chimpanzees (Pan troglodytes) given the prominence of this species in comparative samples used in human evolution research and the key role of the maxilla in such studies. Size and shape were analysed using three-dimensional geometric morphometric methods based on computed tomography scans of 94 wild and 30 captive specimens. Captive individuals have on average larger and more asymmetrical maxillae than wild chimpanzees, and significant differences are present in their maxillary shapes. A large proportion of these shape differences are attributable to static allometry, but wild and captive specimens still differ significantly from each other after allometric size adjustment of the shape data. Levels of shape variation are higher in the captive group, while the degree of size variation is likely similar in our two samples. Results are discussed in the context of ontogenetic growth trajectories, changes in dietary texture, an altered social environment, and generational differences. Additionally, sample simulations show that size and shape differences between chimpanzees and bonobos (Pan paniscus) are exaggerated when part of the wild sample is replaced with captive chimpanzees. Overall, this study confirms that maxillae of captive chimpanzees should not be included in morphological or taxonomic analyses when the objective is to characterise the species.

A longitudinal comparison of maternal behaviour in German urban humans (Homo sapiens) and captive chimpanzees (Pan troglodytes)

Comparative perspectives are crucial in the study of human development, yet longitudinal comparisons of humans and other primates are still relatively uncommon. Here, we combined theoretical frameworks from cross-cultural and comparative psychology, to study maternal style in 10 mother–infant pairs of German urban humans (Homo sapiens) and 10 mother–infant pairs of captive chimpanzees (Pan troglodytes), during the first year of infants’ development. We conducted focal observations of different behaviours (i.e. nursing, carrying, body contact, touching, grooming, restraining, approaching, leaving, rejection, aggression, mutual gaze, object stimulation), during natural interactions. Analyses revealed a more distal maternal style in WEIRD humans than in captive chimpanzees, with different behaviours being generally more common in one of the two species throughout development. For other behaviours (i.e. nursing), developmental trajectories differed between WEIRD humans and captive chimpanzees, although differences generally decreased through infants’ development. Overall, our study confirms functional approaches as a valid tool for comparative longitudinal studies.

Clinical Manifestations of an Outbreak of Monkeypox Virus in Captive Chimpanzees in Cameroon, 2016.

Monkeypox virus (MPXV) is a reemerging virus of global concern. An outbreak of clade I MPXV affected 20 captive chimpanzees in Cameroon in 2016. We describe the epidemiology, virology, phylogenetics, and clinical progression of this outbreak. Clinical signs included exanthema, facial swelling, perilaryngeal swelling, and eschar. Mpox can be lethal in captive chimpanzees, with death likely resulting from respiratory complications. We advise avoiding anesthesia in animals with respiratory signs to reduce the likelihood of death. This outbreak presented a risk to animal care staff. There is a need for increased awareness and a One Health approach to preparation for outbreaks in wildlife rescue centers in primate range states where MPXV occurs. Control measures should include quarantining affected animals, limiting human contacts, surveillance of humans and animals, use of personal protective equipment, and regular decontamination of enclosures.

Naïve, adult, captive chimpanzees do not socially learn how to make and use sharp stone tools

Although once regarded as a unique human feature, tool-use is widespread in the animal kingdom. Some of the most proficient tool-users are our closest living relatives, chimpanzees. These repertoires however consist primarily of tool use, rather than tool manufacture (for later use). Furthermore, most populations of chimpanzees use organic materials, such as sticks and leaves, rather than stones as tools. This distinction may be partly ecological, but it is also important as chimpanzees are often used as models for the evolution of human material culture, the oldest traces of which consist of manufactured sharp stone tools (so-called “flakes”). Thus, examining the conditions (if any) under which chimpanzees may develop flake manufacture and use can provide insight into the drivers of these behaviours in our own lineage. Previous studies on non-human apes’ ability to make and use flakes focused on enculturated apes, giving them full demonstrations of the behaviour immediately, without providing social information on the task in a stepwise manner. Here we tested naïve, captive chimpanzees (N = 4; three potentially enculturated and one unenculturated subject) in a social learning experimental paradigm to investigate whether enculturated and/or unenculturated chimpanzees would develop flake making and use after social information of various degrees (including a human demonstration) was provided in a scaffolded manner. Even though social learning opportunities were provided, neither the unenculturated subject nor any of the potentially enculturated subjects made or used flakes, in stark contrast to previous studies with enculturated apes. These data suggest that flake manufacture and use is outside of our tested group of captive chimpanzees’ individual and social learning repertoires. It also suggests that high levels of enculturation alongside human demonstrations (and/or training) may be required before captive chimpanzees can develop this behaviour.

Captive chimpanzee shares food with baboons.

Captive chimpanzee shares food with baboons.

Vulvar squamous cell carcinoma in a captive female chimpanzee: A case report.

A necropsy was performed on a 43-year-old female zoo chimpanzee, with cancer in the vulvar and perivulvar region. She was diagnosed with squamous cell carcinoma, the presence of this tumor in domestic animals and non-human primates is very rare in the vulvar region and there were no previous reports found on it in chimpanzee, due to which this report contributes to the knowledge on chimpanzee pathologies.

The Role of Applied Behaviour Analysing in Zoo Management System for Animals

This study examines the use of Applied Behaviour Analysis (ABA) in animal management systems in zoos with an emphasis on how well it enhances animal wellbeing. The goals of the study were comparing ABA-based approaches to conventional zoo management techniques and evaluating the effect of ABA on stress reduction in captive chimpanzees. Over the course of a year, information was gathered from a chosen group of chimpanzees, including baseline and post-ABA stress levels. Following the use of ABA techniques, the data from Table 1 show a consistent trend among the chimpanzees, suggesting a considerable reduction in stress levels. Strong evidence for the effectiveness of ABA in lowering stress levels in the chimpanzees was given by statistical analysis of the data (Table 2). With a high t-statistic of 8.25, the mean baseline stress level of 7.7 substantially decreased to 3.5 post-ABA treatments (p 0.05), emphasizing the significance of this reduction. With regard to reducing stress, Objective 2 compared ABA-Based and Traditional groups. Compared to the Traditional group, the ABA-Based method had a reduced baseline stress level, according to the findings in Table 3. The ABA-Based group showed a significant reduction in stress levels following ABA sessions, while the Traditional group also showed a reduction in stress levels, albeit to a lesser extent. Both strategies significantly reduced stress, according to statistical analysis (Table 4), with the ABA-Based strategy having a greater degree of statistical significance (p 0.05). This study concludes by offering empirical proof that Applied Behaviour Analysis is a useful method for enhancing animal wellbeing in the context of zoo management. The findings imply that when compared to conventional management techniques, ABA therapies can significantly lower stress levels in caged animals.

Behavioral Welfare Research for the Management of Sanctuary Chimpanzees (Pan troglodytes).

Chimp Haven is a sanctuary for chimpanzees retired from biomedical research, rescued from the pet trade, or re-homed after other organizations could no longer care for them. To provide optimal care for over 300 chimpanzees, Chimp Haven's animal care team includes experts in behavioral science, veterinary treatment, and husbandry practices. To aid these teams in making routine welfare management decisions, a system of behavioral metrics provides objective data to guide decisions and track outcomes. Chimp Haven has built and piloted seven behavioral metric protocols over the past 5 years to provide staff with an objective and comprehensive picture of the chimpanzees' behavioral welfare. The data from behavioral observations, staff surveys, and routine staff documentation are analyzed and processed through Google Forms, ZooMonitor, Microsoft Power Bi, Microsoft Excel, and R. Each metric assists staff in making data-based decisions regarding the management of captive chimpanzees related to abnormal behavior, hair loss, wounding, social relationships, positive reinforcement training and overall wellness. In this article, we explore examples of each metric and how they have been utilized to monitor and make decisions for both social groups of chimpanzees as well as individuals. These metrics can be collected and shared easily in an understandable format, which may provide an important framework for others to follow to enable the tracking of welfare for other sanctuaries, non-human primates, as well as other species.

Rols de cacera en ximpanzés? Aspectes cognitius de l’activitat grupal en aquesta espècie

Observations of chimpanzees in their natural habitat show that as well as competing, these primates often cooperate by forming coalitions, patrolling the boundaries of their territories, and hunting in groups. Perhaps because of the important role it is thought to have played in the evolution of our own species, group hunting behaviours have attracted considerable research interest. The underlying question is to what extent do chimpanzees hunt cooperatively in a human-like manner? To answer this question, we must consider not only their behaviour, but also the cognitive abilities required, given that any two similar behaviours may respond to different psychological mechanisms. Research on the cognitive aspect of cooperation has been carried out mainly through experiments with chimpanzees in captivity. The available evidence suggests that, with experience, chimpanzees are capable of coordination between individuals, but it is unclear whether they can also cooperate, i.e., act according to a common strategy.

Natural Non-Polio-Enteroviruses Detected in Captive Mandrills (Mandrillus sphinx) and Chimpanzees (Pan troglodytes troglodytes) Housed in a Primate Center in Franceville, Gabon

Natural Non-Polio-Enteroviruses Detected in Captive Mandrills (Mandrillus sphinx) and Chimpanzees (Pan troglodytes troglodytes) Housed in a Primate Center in Franceville, Gabon

Calcium salt crystalluria in a captive chimpanzee (Pantroglodytes) population.

Urinalysis is a rapid, non-invasive method used to obtain diagnostic information on primates. While several studies have investigated dipstick and specific gravity values in chimpanzees, urine sediment analysis is often excluded. Crystalluria, observed during urine sediment analysis, can be benign or indicate renal pathologies. In total, 665 urine samples from sanctuary-housed chimpanzees were analyzed over the course of 17 months for pH, specific gravity, time of collection, and crystalluria. Calcium salt crystalluria was seen in 9.0% of the samples from 23.7% of the individuals in the study. Urinary pH and specific gravity were significantly higher in samples with crystalluria than in those lacking crystalluria, while time of collection did not differ between the two groups. While diet is the most likely cause of the crystalluria in this population, several medications could also cause urinary crystallization. Further exploration of the significance of calcium salt crystalluria in chimpanzees is warranted.

Face to face interactions in chimpanzee (Pan troglodytes) and human (Homo sapiens) mother-infant dyads.

Human mothers interact with their infants in different ways. In Western, educated, industrialized, rich and democratic (WEIRD) societies, face-to-face interactions and mutual gazes are especially frequent, yet little is known about their developmental trajectories and if they differ from those of other primates. Using a cross-species developmental approach, we compared mother-infant interactions in 10 dyads of urban humans from a WEIRD society (Homo sapiens) and 10 dyads of captive zoo-based chimpanzees (Pan troglodytes), when infants were one, six and 12 months old. Results showed that face-to-face interactions with mutual gaze events were common in both groups throughout the infant's first year of life. The developmental trajectories of maternal and infants' looks partially differed between species, but mutual gaze events were overall longer in humans than in chimpanzees. Mutual gazes were also more frequent in humans, peaking at six months in humans, while increasing with age in chimpanzees. The duration and frequency of mutual gazes varied across contexts in both groups, with mutual gazes being longer during caring/grooming and feeding contexts. These findings confirm that some aspects of early socio-cognitive development are shared by humans and other primates, and highlight the importance of combining developmental and cross-species approaches to better understand the evolutionary roots of parenting behaviour. This article is part of a discussion meeting issue 'Face2face: advancing the science of social interaction'.

Locomotion as a Measure of Well-Being in Captive Chimpanzees (Pan troglodytes).

Locomotion in non-human primates, including walking, climbing, and brachiating among other types of movement (but not pacing), is a species-typical behavior that varies with age, social housing conditions, and environmental factors (e.g., season, food availability, physical housing conditions). Given that captive primates are typically observed to engage in lower levels of locomotor behaviors than their wild counterparts, increases in locomotion are generally considered to be indicative of improved welfare in captivity. However, increases in locomotion do not always occur with improvements in welfare, and sometimes occur under conditions of negative arousal. The use of time spent in locomotion as a welfare indicator in studies of well-being is relatively limited. We conducted focal animal observations on 120 captive chimpanzees across a series of studies and found higher percentages of time spent in locomotion (1) upon transfer to a new enclosure type, (2) in larger groups with wider within-group age ranges, and fewer males, and (3) with participation in an experimental medication choice paradigm. We also found that, among geriatric chimpanzees, those housed in nongeriatric groups exhibited more locomotion than those living in geriatric groups. Lastly, locomotion was significantly negatively correlated with several indicators of poor welfare and significantly positively correlated with behavioral diversity, one indicator of positive welfare. Overall, the increases in time spent in locomotion observed in these studies were part of an overall behavioral pattern indicative of enhanced welfare, suggesting that an increase in time spent in locomotion itself may be an indicator of enhanced welfare. As such, we suggest that levels of locomotion, which are typically assessed in most behavioral experiments, may be used more explicitly as indicators of welfare in chimpanzees.

Demography and epidemiology of captive former biomedical research chimpanzees (Pan troglodytes) 1: Survival and mortality.

Accurate and up-to-date data on longevity and mortality are essential for describing, analyzing, and managing animal populations in captivity. We assembled a comprehensive demography data set and analyzed survival and mortality patterns in a population of captive former biomedical research chimpanzees. The study synthesized over 51,000 life-years of demographic data collected on 2349 individuals between 1923 and 2014. Our goal was to assess the population's current age-sex composition, estimate rates of survivorship, mortalityand life expectancy, and compare findings withother chimpanzee populations of interest. Results indicated an increasingly geriatric contemporary population declining in size. The median life expectancy (MLE) of the entire population was 32.6 years (males 29.1, females 36.1). For chimpanzees who reached 1year of age, the MLE increased to 34.9 years (males 31.0, females 38.8). Survival probability was influenced by both sex and birth type. Females exhibited greater survivorship than males (β1 = -0.34, z = -5.74, p < 0.001) and wild-born individuals exhibited greater survivorship than captive-born individuals (β2 = -0.55, z = -5.89, p < 0.001). There was also a seasonal trend in mortality, wherein more individuals died during the winter months (December-February) compared withother seasons. Analyses of life expectancy over time showed continual increases in both median age of living individuals and median age at death, suggesting that these chimpanzees have yet to reach their full aging potential in a postresearch environment. As they continue to age, ongoing monitoring and analysis of demographic changes will be necessary for science-based population and program management until extinction occurs some decades in the future.