A review of research in primate sanctuaries

Development and assessment of a stair ascension challenge as a measure of aging and physical function in nonhuman primates

Nonhuman primates (NHPs) are valuable models for studying healthspan, including frailty development. Frailty metrics in people centers on functional measures, including usual gait speed which can be predictive of all-cause mortality. This concept that physical competencies are able to prognosticate an individual's health trajectory over chronologic aging is well-accepted and has led to refinements in how physical function is evaluated, and include measures of strength and power along with walking speed. NHP studies of aging require evaluation of physical function, which can be difficult in field and research settings. We compared stair climb velocity to usual walking speed in 28 peri-geriatric to geriatric NHPs, as incorporating a climbing obstacle integrates multiple components of physical function: isolated leg and back strength, proprioception, balance, and range of motion. We find that stair climbing speed was reliable between observers, and whether timing was in-person take from video capture. The stair climb rates were 50% more associated with chronological age than walking speed (R = -0.68 vs. -0.45) and only stair climbing speeds were retained as predictive of age when walking speed and bodyweight were included in multivariate models (overall R2  = 0.44; p < 0.0001). When comparing young (10-16 years) versus geriatric (16-29 years) stair climbing speed was significantly different (p < 0.001), while walking speeds only tended to be slower (p = 0.12) suggesting that the additional challenge of a stair climb better unmasks subclinical frailty development that usual walking speed.

Group structure and individual relationships of sanctuary-living Grauer's gorillas (Gorilla beringei graueri)

The study of individual social relationships and group structure provides insights into a species' natural history and can inform management decisions for animals living in human care. The Gorilla Rehabilitation and Conservation Education (GRACE) center provides permanent sanctuary for a group of 14 Grauer's gorillas (Gorilla beringei graueri), a critically endangered and poorly studied subspecies of the genus gorilla, in the Democratic Republic of the Congo. We monitored the association patterns of the gorillas at GRACE over eight months and here describe their individual relationships and group structure via multiple social network statistics. The group was highly connected but associations between individuals were weak on average. Social network metrics describe that an adult female was the most gregarious and socially central individual within the group. In fact, adult females were the most gregarious and socially central on average. Group level association patterns were significantly correlated over the study period and across observation types, suggesting the group was socially stable during the eight month study period. The data collected in this study were done so by GRACE caregivers as part of their daily husbandry routine and provided important insights into this group's behavior, ultimately informing on their care, welfare and future release considerations. The methodological approaches implemented here are easily scalable to any primate sanctuary or care facility seeking to use data to inform husbandry and management procedures. Lastly, our study is the first social network analysis to be conducted on Grauer's gorillas and provides tentative insights into the behavior of this poorly studied subspecies. Though more research is needed to evaluate if the findings here are reflective of this subspecies' natural history or the idiosyncrasies of the group.

Group-specific expressions of co-feeding tolerance in bonobos and chimpanzees preclude dichotomous species generalizations

Bonobos are typically portrayed as more socially tolerant than chimpanzees, yet the current evidence supporting such a species-level categorization is equivocal. Here, we used validated group-level co-feeding assays to systematically test expressions of social tolerance in sixteen groups of zoo- and sanctuary-housed bonobos and chimpanzees. We found that co-feeding tolerance substantially overlaps between the species, thus precluding categorical inference at the species level. Instead, marked differences were observed between groups, with some bonobo communities exhibiting higher social tolerance than chimpanzee communities, and vice versa. Moreover, considerable intergroup variation was found within species living in the same environment, which attests to Pan's behavioral flexibility. Lastly, chimpanzees showed more tolerance in male-skewed communities, whereas bonobos responded less pronounced to sex-ratio variation. We conclude that the pervasive dichotomy between the tolerant bonobo and the belligerent chimpanzee requires quantitative nuance, and that accurate phylogenetic tracing of (human) social behavior warrants estimations of intraspecific group variation.

Observational approaches to chimpanzee behavior in an African sanctuary: Implications for research, welfare, and capacity-building

Research in African ape sanctuaries has emerged as an important context for our understanding of comparative cognition and behavior. While much of this work has focused on experimental studies of cognition, these animals semi-free-range in forest habitats and therefore can also provide important information about the behavior of primates in socioecologically-relevant naturalistic contexts. In this "New Approaches" article, we describe a project where we implemented a synthetic program of observational data collection at Ngamba Island Chimpanzee Sanctuary in Uganda, directly modeled after long-term data collection protocols at the Kibale Chimpanzee Project in Uganda, a wild chimpanzee field site. The foundation for this project was a strong partnership between sanctuary staff, field site staff, and external researchers. We describe how we developed a data-collection protocol through discussion and collaboration among these groups, and trained sanctuary caregivers to collect novel observational data using these protocols. We use these data as a case study to examine: (1) how behavioral observations in sanctuaries can inform primate welfare and care practices, such as by understanding aggression within the group; (2) how matched observational protocols across sites can inform our understanding of primate behavior across different contexts, including sex differences in social relationships; and (3) how more robust collaborations between foreign researchers and local partners can support capacity-building in primate range countries, along with mentoring and training students more broadly.

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.

Viruses in saliva from sanctuary chimpanzees (Pan troglodytes) in Republic of Congo and Uganda

Pathogen surveillance for great ape health monitoring has typically been performed on non-invasive samples, primarily feces, in wild apes and blood in sanctuary-housed apes. However, many important primate pathogens, including known zoonoses, are shed in saliva and transmitted via oral fluids. Using metagenomic methods, we identified viruses in saliva samples from 46 wild-born, sanctuary-housed chimpanzees at two African sanctuaries in Republic of Congo and Uganda. In total, we identified 20 viruses. All but one, an unclassified CRESS DNA virus, are classified in five families: Circoviridae, Herpesviridae, Papillomaviridae, Picobirnaviridae, and Retroviridae. Overall, viral prevalence ranged from 4.2% to 87.5%. Many of these viruses are ubiquitous in primates and known to replicate in the oral cavity (simian foamy viruses, Retroviridae; a cytomegalovirus and lymphocryptovirus; Herpesviridae; and alpha and gamma papillomaviruses, Papillomaviridae). None of the viruses identified have been shown to cause disease in chimpanzees or, to our knowledge, in humans. These data suggest that the risk of zoonotic viral disease from chimpanzee oral fluids in sanctuaries may be lower than commonly assumed.

COVID-19's Impact on the Pan African Sanctuary Alliance: Challenging Times and Resilience from Its Members

The worldwide pandemic caused by SARS-CoV-2 challenged conservation organizations. The lack of tourism has benefited or negatively affected wildlife organizations in various ways, with several primate sanctuaries struggling to cope with the COVID-19 crisis and to keep providing for their inhabitants. In addition, the genetic similarity between great apes and humans puts them at higher risk than any other species for the transmission of COVID-19. PASA is a non-profit organization comprising 23 sanctuaries, and cares for many species of primate, including African great apes. In light of the pandemic, we aimed to understand the direct effects of COVID-19 on PASA management throughout three time periods: before (2018-2019), at the start of (2019-2020), and during (2020-2021) the pandemic. We collected data via annual surveys for PASA members and ran Generalized Linear Mixed Models to highlight any significant differences in their management that could be linked to COVID-19. Our findings demonstrated no particular impact on the number of primates rescued, employees, or expenses. However, revenues have been decreasing post-COVID-19 due to the lack of income from tourism and volunteer programs. Nonetheless, our results reveal a form of resilience regarding the sanctuaries and the strategy applied to maintain their management. Consequently, we emphasize the specific impacts of the COVID-19 outbreak and its repercussions for conservation work. We discuss the difficulties that sanctuaries have faced throughout the crisis and present the best measures to prevent future outbreaks and protect biodiversity.

Chimpanzees (Pan troglodytes) in U.S. Zoos, Sanctuaries, and Research Facilities: A Survey-Based Comparison of Species-Typical Behaviors

A survey was sent to zoos, research facilities, and sanctuaries which housed chimpanzees. Data collected included information about 1122 chimpanzees’ age, sex, social group-size, rearing history, and enclosure. Respondents were also asked to indicate if certain behaviors had been observed in each chimpanzee over the prior two years. Species- typical behaviors (STBs) were queried, including copulation, tool-use, nest-building, and social grooming. Tool-use was reported present for 94.3% of the sample (n = 982), active social grooming for 85.7% (n = 1121), copulation for 68.3% (n = 863) and nest-building for 58.9% (n = 982). Of the subjects for whom we had data regarding all four STBs (n = 860), 45.6% were reported to engage in all four. Logistic regression analyses using forward Wald criteria were conducted to determine the best model for each STB based on the predictors of age, sex, rearing history, group-size, facility-type, and a sex-by-rearing interaction. The best model for copulation (χ2(6) = 124.62, p < 0.001) included rearing, group-size, facility-type, and the sex-by-rearing interaction. Chimpanzees were more likely to copulate if they were mother-reared, in larger groups, living in research facilities, and, if not mother-reared (NOTMR), more likely to copulate if they were female. The best model for tool-use retained the predictors of age category, facility-type, and sex-by-rearing (χ2(5) = 55.78, p < 0.001). Chimpanzees were more likely to use tools if they were adult, living in research facilities, and if NOTMR, were female. The best model for nest-building included facility-type and rearing (χ2(3) = 205.71, p < 0.001). Chimpanzees were more likely to build nests if they were MR and if they were living in zoos or in sanctuaries. The best model for active social grooming retained the predictors of age, sex, rearing, and type of facility (χ2(6) = 102.15, p < 0.001). Chimpanzees were more likely to engage in active social grooming if they were immature, female, mother-reared, and living in zoos. This research provides a basic behavioral profile for many chimpanzees living under human care in the United States and allows us to determine potential methods for improving the welfare of these and future chimpanzees in this population.

Viruses in sanctuary chimpanzees across Africa

Infectious disease is a major concern for both wild and captive primate populations. Primate sanctuaries in Africa provide critical protection to thousands of wild-born, orphan primates confiscated from the bushmeat and pet trades. However, uncertainty about the infectious agents these individuals potentially harbor has important implications for their individual care and long-term conservation strategies. We used metagenomic next-generation sequencing to identify viruses in blood samples from chimpanzees (Pan troglodytes) in three sanctuaries in West, Central, and East Africa. Our goal was to evaluate whether viruses of human origin or other "atypical" or unknown viruses might infect these chimpanzees. We identified viruses from eight families: Anelloviridae, Flaviviridae, Genomoviridae, Hepadnaviridae, Parvoviridae, Picobirnaviridae, Picornaviridae, and Rhabdoviridae. The majority (15/26) of viruses identified were members of the family Anelloviridae and represent the genera Alphatorquevirus (torque teno viruses) and Betatorquevirus (torque teno mini viruses), which are common in chimpanzees and apathogenic. Of the remaining 11 viruses, 9 were typical constituents of the chimpanzee virome that have been identified in previous studies and are also thought to be apathogenic. One virus, a novel tibrovirus (Rhabdoviridae: Tibrovirus) is related to Bas-Congo virus, which was originally thought to be a human pathogen but is currently thought to be apathogenic, incidental, and vector-borne. The only virus associated with disease was rhinovirus C (Picornaviridae: Enterovirus) infecting one chimpanzee subsequent to an outbreak of respiratory illness at that sanctuary. Our results suggest that the blood-borne virome of African sanctuary chimpanzees does not differ appreciably from that of their wild counterparts, and that persistent infection with exogenous viruses may be less common than often assumed.

The Benefits and Challenges of Conducting Primate Research in Different Settings

Internationally, primate research takes place in laboratories, zoos, sanctuaries, and the wild. All of these settings present unique advantages and challenges in terms of methodology, translatability, animal welfare, and ethics. In this novel commentary, we explore the scientific and ethical benefits and drawbacks of conducting non-invasive psychological research with primates in each setting. We also suggest ways to overcome some of the barriers. We argue that while there may be greater experimental control in laboratory-based research, settings that more closely mirror primates' natural habitats are generally better suited to meet their specialized needs. More naturalistic research settings, including field studies, may also circumvent some ethical concerns associated with research in captivity, and yield more ecologically valid data.

Primate cognition in zoos: Reviewing the impact of zoo-based research over 15 years

Primate cognition research is reliant on access to members of the study sp ecies and logistical infrastructures to conduct observations and experiments. Historically founded in research centers and private collections, and spreading to modern zoos, sanctuaries, and the field, primate cognition has been investigated in diverse settings, each with benefits and challenges. In our systematic review of 12 primatology, animal behavior, and animal cognition journals over the last 15 years, we turn a spotlight on zoos to quantify their current impact on the field and to highlight their potential as robust contributors to future work. To put zoo-based research in context, we compare zoos to three other site types: university-owned or independent research centers, sanctuaries, and field sites. We assess the contributions of zoos across several critical considerations in primate cognition research, including number of investigations, species diversity, sample size, research topic diversity, and methodology. We identified 1119 publications reporting studies of primate cognition, almost 25% of which report research conducted in zoos. Across publications, zoo-based research has greater species diversity than research centers and covers a diverse range of research topics. Although our review is merely a snapshot of primate cognition research, our findings suggest that zoos may present advantages to researchers regarding species diversity, and lack some of the methodological constraints of field sites, allowing greater ease of access to a diverse range of subjects for cognition investigations. We suggest that zoos have great potential as key contributors for future investigations in primate cognition. Finally, we shed light on the symbiotic relationship that can emerge between researchers and zoos, forming partnerships that bring unique advantages to both parties.

Primatology in zoos: Studying behavior, cognition, and welfare

Primatological research in zoos is increasing globally. Such research allows scientists to study primate biology, behavior, and cognition while helping to advance the welfare of captive primates. Moreover, zoos welcome millions of visitors annually, which creates unique opportunities for public engagement with this research. Reflecting the importance of zoos in the field of primatology, the articles in this special issue showcase the range of primatological research currently being conducted in zoos around the world. With this special issue, I have chosen to focus on research examining primate behavior and cognition, addressing both basic and applied questions. The articles included in this special issue also highlight the array of technologies and methods being used to study zoo-housed primates. While zoos house a variety of primate species, potentially enabling the testing of under-studied species or widescale comparative research, great apes are disproportionately represented in current zoo-based research. Thus, while an interest in conducting research with primates in zoos continues to grow, there are still opportunities to increase the breadth and diversity of this study.

Behavioural Development of Three Former Pet Chimpanzees a Decade after Arrival at the MONA Sanctuary

Chimpanzees used as pets and in the entertainment industry endure detrimental living conditions from early infancy onwards. The preferred option for ending their existence as pet or circus chimpanzees is their rescue and transfer to a primate sanctuary that will provide them with optimal living and social conditions, so that they can thrive. In this case study, we had the rare opportunity to compare the activity budgets of three chimpanzees from their time as pets in 2004 to their time living at the MONA sanctuary in 2020, after almost a decade in the centre. We found their behaviour patterns changed in accordance with the sanctuaries' rehabilitation objectives. Resting periods increased considerably while vigilance simultaneously declined sharply. Moreover, the chimpanzees' social competence increased as allogrooming became the predominant social behaviour, and agonistic interactions diminished even though they were living within a larger social group at the sanctuary. All three chimpanzees expanded their allogrooming and proximity networks at the sanctuary, which included new group members, but they maintained the closest relationships to those conspecifics who they were rescued with. In conclusion, these findings suggest that the sanctuary environment and social group setting made it possible for these three chimpanzees to improve their social competence and increase their well-being over time.

Invasive Research on Non-Human Primates-Time to Turn the Page

Simple Summary

Despite increasing ethical concerns, primates are still often used in invasive research (i.e., laboratory research that causes body manipulations causing them pain or distress and not aimed at directly improving their well-being). Here, we will review previous studies showing that primates have complex behaviour and cognition, and that they suffer long-term consequences after being used in invasive research. We will discuss the ethical problems that invasive research on primates posit, the legal protection that they are, to date, granted in different countries, and summarize the past and current attempts to ban this kind of research on primates. We will conclude why, in our opinion, invasive research on primates should be banned, and non-invasive methods should be considered the only possible approach to the study of primates.

Abstract

Invasive research on primates (i.e., laboratory research that implies body manipulations causing pain or distress that is not aimed to directly improve the individuals’ well-being) has a long history. Although some invasive studies have allowed answering research questions that we could not have addressed with other methods (or at least not as quickly), the use of primates in invasive research also raises ethical concerns. In this review, we will discuss (i) recent advances in the study of primates that show evidence of complex behaviour and cognition, (ii) welfare issues that might arise when using primates in invasive research, (iii) the main ethical issues that have been raised about invasive research on primates, (iv) the legal protection that primates are granted in several countries, with a special focus on the principle of the 3Rs, and (v) previous and current attempts to ban the use of primates in invasive research. Based on this analysis, we suggest that the importance of a research question cannot justify the costs of invasive research on primates, and that non-invasive methods should be considered the only possible approach in the study of primates.

The application of noninvasive, restraint-free eye-tracking methods for use with nonhuman primates

Over the past 50 years there has been a strong interest in applying eye-tracking techniques to study a myriad of questions related to human and nonhuman primate psychological processes. Eye movements and fixations can provide qualitative and quantitative insights into cognitive processes of nonverbal populations such as nonhuman primates, clarifying the evolutionary, physiological, and representational underpinnings of human cognition. While early attempts at nonhuman primate eye tracking were relatively crude, later, more sophisticated and sensitive techniques required invasive protocols and the use of restraint. In the past decade, technology has advanced to a point where noninvasive eye-tracking techniques, developed for use with human participants, can be applied for use with nonhuman primates in a restraint-free manner. Here we review the corpus of recent studies (N=32) that take such an approach. Despite the growing interest in eye-tracking research, there is still little consensus on "best practices," both in terms of deploying test protocols or reporting methods and results. Therefore, we look to advances made in the field of developmental psychology, as well as our own collective experiences using eye trackers with nonhuman primates, to highlight key elements that researchers should consider when designing noninvasive restraint-free eye-tracking research protocols for use with nonhuman primates. Beyond promoting best practices for research protocols, we also outline an ideal approach for reporting such research and highlight future directions for the field.