Primate puzzleboard: A simple environmental enrichment device for captive chimpanzees

An Evaluation of Ethograms Measuring Distinct Features of Enrichment Use by Captive Chimpanzees (Pan troglodytes)

Simple Summary

Environmental enrichment for chimpanzees is important in order to minimize boredom and stress in captivity and to provide opportunities to engage in species-typical behaviors. However, few studies have investigated potential associations between enrichment objects, manipulation behaviors, and social contexts, nor have they examined if individual chimpanzees vary in their enrichment object preferences. In the current study, three ethograms were used to code the use of enrichment objects, engagement in manipulation behaviors, and social contexts of enrichment use of captive chimpanzees (Pan troglodytes). Data mining from a video archive consisting of 2054 videos collected over a decade allowed the ethograms to be applied to 732 min and 58 s of videos. Some enrichment objects were more often associated with specific manipulation behaviors and social contexts, indicating that enrichment objects might serve distinct social and behavioral purposes. The chimpanzees differed in their enrichment object preferences, suggesting that caregivers of captive chimpanzees should consider individual needs when providing enrichment in order to improve chimpanzees’ experiences in captivity. Finally, the majority of enrichment object use and manipulation behaviors were able to be categorized, indicating that our ethograms were largely effective in coding enrichment use.

Abstract

Environmental enrichment provides mental stimulation and minimizes abnormal behaviors in captive animals. In captive chimpanzees, individual animals may vary in the ways in which they benefit from enrichment or use enrichment devices, so investigating nuances in enrichment use may improve the welfare of captive chimpanzees. In the current study, three ethograms measuring distinct features of enrichment use (i.e., enrichment object, manipulation behavior, and social context) were evaluated by coding videos of captive chimpanzees (Pan troglodytes) at Chimpanzee Sanctuary Northwest in Cle Elum, WA. A total of 732 min and 58 s of video footage was coded from a larger video archive (i.e., 2054 videos) of enrichment use that spanned a decade. A principal component analysis (PCA) revealed that different categories of enrichment objects were more often associated with specific manipulation behaviors and social contexts, suggesting that enrichment objects might fulfill different behavioral and social needs in captivity. Specifically, toy objects were associated with active tactile behaviors in affiliative contexts while oral behaviors were used with foraging objects in solitary contexts. Additionally, individual chimpanzees showed unique preferences for enrichment objects, indicating that caregivers of captive chimpanzees should consider individual needs instead of a “one size fits all” approach to enrichment provisions.

Confronting Back-of-House Traditions: Primates as a Case Study

This review commentary focuses on traditional management practices and facility design with suggested improvements in non-public primate management areas, often called “back-of-house”, (henceforth BOH) in zoos, sanctuaries, and research facilities. Progress has been made toward improving animal quality of life in larger, more naturalistic, and enriched indoor and outdoor display areas. However, the quality of life in BOH areas has improved little in comparison. Basic management, regulatory, structural, and spatial BOH environments are lagging, especially in the developing world, and animals may be confined in less enriching spaces for substantial periods of the 24 h day. We reviewed traditional management policy and practice, as well as newer training, enrichment, and welfare policies and actions, and suggested alternatives for structural environments and spatial environments. The suggestions included using more animal-friendly construction materials and animal–computer interaction, providing greater control of the ambient environment and choice of access to multiple areas by the animals themselves, and designing for optimal animal wellbeing at all times, including when caregivers are no longer present. Case studies focused on primates were included. We concluded by suggesting a new, integrated design model based not upon rote standards and old models but building on empirical foundations while embracing empathy and innovation.

Cognitive enrichment in a social setting: assessing the use of a novel food maze in sanctuary-housed chimpanzees

Foraging devices are effective enrichment tools for non-human primates, as they provide both cognitive and manipulative stimulation that may enhance these animals’ welfare. We assessed the behavioral effects of a novel tool-based enrichment on 14 chimpanzees (Pan troglodytes) housed at Fundació Mona (Girona, Spain). The device consisted of a vertical maze filled with food rewards, which chimpanzees could extract by using tools. We conducted behavioral observations in two conditions over an approximately 2.5-month period: when the food maze was loaded (12 enrichment days), and when it was empty (12 baseline days). Data were collected using 2-min scan sampling and untimed-event focal sampling during two daily sessions of 80 min each. We expected that the chimpanzees’ interest in the enrichment would decrease over time, but that its use would be linked to an increase in the occurrence of species-typical behaviors, a reduction in negative indicators of welfare, and changes in social behaviors. We found that participation widely varied among subjects, being higher in females and decreasing through time. Furthermore, participation was linked to an increase in tool use and a decrease in inactivity, but also to an increase in aggression-related behaviors. In contrast, participation had no effect on the occurrence of abnormal behaviors, social proximity or affiliation-related behaviors. Finally, we detected an increase in self-directed behaviors only when subjects actively interacted with the device. We conclude that, in future studies, these types of devices should be evaluated for longer periods of time and more attention should be paid to individuals’ preferences and abilities.

Artificial Termite-Fishing Tasks as Enrichment for Sanctuary-Housed Chimpanzees: Behavioral Effects and Impact on Welfare

Simple Summary

The welfare of captive animals is nowadays a topic of major concern. In order to express their natural behavioral repertoires, however, animals require complex environments and stimuli which are difficult to reproduce in captivity. To overcome this, environmental enrichment is considered one of the most successful tools to increase behavioral opportunities and enhance animal welfare. In this study, we explored whether providing an artificial termite-fishing task, and whether participation in this task, predicted changes in the solitary and social behavior of sanctuary-housed chimpanzees (Pan troglodytes). We compared chimpanzee behavior when the enrichment was presented to different periods without enrichment. We found that the presence of the enrichment predicted an increase in tool use and feeding behavior and a decrease in inactivity, especially for those chimpanzees with higher participation. However, we did not detect significant changes in abnormal or self-directed behaviors. Furthermore, we found no variation in affiliation- or aggression-related behaviors, but social proximity increased in chimpanzees that participated more. Our results support previous studies demonstrating that artificial termite-fishing promotes species-typical behaviors in captive chimpanzees with no major effects on social activities.

Abstract

Artificial termite-fishing tasks are a common enrichment for captive great apes, promoting species-typical behaviors. Nonetheless, whether these activities are linked to changes in other behaviors and whether these changes persist over time has seldom been investigated. We assessed whether the use of an artificial termite-fishing task was linked to changes in the solitary behavior and social dynamics in two groups of sanctuary-housed chimpanzees (Pan troglodytes). Specifically, we compared chimpanzee behavior during eight enrichment sessions distributed over a two-month period, with similar periods before and after the introduction of the enrichment. Data were collected from combined interval and continuous sampling methods and were analyzed using generalized linear mixed models. We found that participation increased across sessions and that both enrichment and participation predicted an increase in tool use and feeding and a decrease in inactivity, which were all maintained throughout the sessions. Furthermore, participation was positively associated with social proximity, revealing a gathering effect of the task. However, neither enrichment nor participation were linked to changes in abnormal, self-directed, affiliation-related or aggression-related behaviors. Overall, our results support the hypothesis that artificial termite-fishing is a suitable enrichment for captive chimpanzees, maintaining the subjects’ interest and promoting species-typical behaviors, with no negative effects on social activities.

Long-Term Macroevaluation of Environmental Enrichment in Three Brown Bears (Ursus arctos) at Barcelona Zoo

The evaluation of enrichment programs is important to determine their effect on nonhuman animal welfare. The daily activity pattern and use of space of 3 brown bears (Ursus arctos) were used for long-term macroevaluation of enrichment to compare the baseline and enrichment phases. Focal sampling methods were used for data collection, and instantaneous scans were made at 2-min intervals during 15 sessions of 1 hr for each animal during the 2 study periods. The enrichment devices were categorized as feeding, occupational, and sensorial. The long-term macroevaluation in 3 bears showed statistically significant differences in some types of activity but not in others. There were also statistically significant differences for the use of space in 4 of the 8 zones in which the enclosures were divided. A more homogenous pattern in the use of space was only observed during the enrichment phase in the old female. The 3 brown bears followed different patterns concerning the enrichment program.

Requirements for the welfare of baboons and pigs used in animal-to-animal xenotransplantation experiments

OBJECTIVE

Review the welfare requirements of pigs and baboons used for xenotransplantation in research laboratories. Because of the requirements to maintain optimum health status, these animals are often kept in barren enclosures with little or no enrichment. They may also be exposed to procedures causing stress and discomfort. Although animal-to-human xenotransplantation is, at the present time, not approved in Australia, research is currently being performed to develop laboratory procedures, using the pig-to-baboon model.

RESULTS AND CONCLUSION

We make recommendations for the husbandry of baboons and pigs used for xenotransplantation, to increase their welfare and minimise stress during experimental procedures, while attempting to preserve the health status required. It is proposed that novel standards should be devised and implemented for baboons, whereas existing pig welfare appraisal schemes could, with minor changes, be suitable for assessing the welfare of pigs used for xenotransplantation.

Enrichment and aggression in primates

There is considerable evidence that primates housed under impoverished conditions develop behavioural abnormalities, including, in the most extreme example, self-harming behaviour. This has implications for all contexts in which primates are maintained in captivity from laboratories to zoos since by compromising the animals' psychological well-being and allowing them to develop behavioural abnormalities their value as appropriate educational and research models is diminished. This review examines the extensive body of literature documenting attempts to improve living conditions with a view to correcting behavioural abnormalities and housing primates in such a way that they are encouraged to exhibit a more natural range and proportion of behaviours, including less self-directed and social aggression. The results of housing, feeding, physical, sensory and social enrichment efforts are examined with specific focus on their effect on aggressive behaviour and variation in their use and efficacy. It is concluded that while inappropriate or poorly distributed enrichment may encourage aggressive competition, enrichment that is species, sex, age and background appropriate can dramatically reduce aggression, can eliminate abnormal behaviour and substantially improve the welfare of primates maintained in captivity.

Behavioral Management of Chimpanzees in Biomedical Research Facilities: The State of the Science

The current status of the behavioral management of chimpanzees housed in US research facilities is examined, and recent advances are described. Behavioral management includes the application of environmental enrichment, animal training, and environmental design for improving animal welfare. Authors surveyed the six major chimpanzee holding facilities and found that the vast majority of chimpanzees are housed socially, with access to the outdoors. The institutions currently invest in behavioral scientists, enrichment specialists, and, most recently, chimpanzee trainers to implement and study chimpanzee behavioral management. This review is based on the substantial scientific literature related to managing social behavior, identifying the behavioral effects of restricted socialization, evaluating various forms of enrichment, and describing positive reinforcement animal training. Authors outline recent accomplishments in behavioral management, summarize behavioral issues that have been evaluated, and identify issues for future consideration. It is proposed that the enhanced application of behavioral management techniques, including training, could significantly reduce chimpanzee stress that is generally associated with experimental manipulations, and could improve animal welfare and the quality of biomedical research. The next challenge is to implement effectively and thoroughly the approaches that have been shown to be beneficial.

Feeding demand conditions and plasma cortisol in socially-housed squirrel monkey mother-infant dyads

Previous studies have demonstrated that experimentally altering the accessibility and availability of food can have profound impact on behavior and adrenocortical activity in nonhuman primate species. In this study, groups of mother-infant squirrel monkey dyads were housed in either high demand (HFD: 120% normal daily food intake provided), low demand (LFD: 600% normal daily food intake provided) or variable demand (VFD: alternating two-week blocks of low demand and high demand) conditions for 12 weeks. During the 12-week experimental foraging phase, animals in the HFD group exhibited prolonged and consistent cortisol elevations. The cortisol levels in the VFD group reflected the ambient demand condition, with higher levels exhibited during the high demand phases of the study, and lower values when the low demand condition was in effect. Overall, mothers were more affected by the experimental manipulation than were infants. The experimental condition did not affect the infants' response to a 24-h separation from their mothers. A suppression of cortisol levels, particularly in the HFD group, was observed upon resumption of ad-libitum feeding.

Injury risks among chimpanzees in three housing conditions

Meeting the psychological needs of chimpanzees (Pan troglodytes) can be a challenge given their aggressiveness on the one hand and the complexity of their social lives on the other. It is unclear how to balance the need to provide opportunities for species-appropriate behavior against potential risks of injury chimpanzees may inflict on each other. This study evaluates the suggestion that simpler social environments protect chimpanzees from wounding. Over a two-year period all visible injuries to 46 adult males, 64 adult females, and 25 immature chimpanzees were recorded at the Yerkes Regional Primate Research Center. Approximately half of the subjects were mother-reared, and the rest were nursery-reared. Housing included compounds containing about 20 chimpanzees, interconnected indoor-outdoor runs for groups of up to 12 individuals, and smaller indoor-outdoor runs for pairs and trios. Annual wounding rates were calculated for serious wounds (extensive injuries and all those requiring veterinary intervention) as well as for minor wounds. Compound-housed chimpanzees incurred the highest level of minor wounding, but serious wounding levels were not affected by housing condition. Even with a period of dominance instability and elevated levels of wounding in one compound, compound chimpanzees were not injured more than those in smaller social groups over the long term. Nursery-reared females in moderate-sized groups were wounded more than mother-reared females. Also, nursery-reared males and females were wounded less often when paired with mother-reared companions. Overall, this study indicates that maintaining chimpanzees in pairs and trios would not be an effective means for reducing injuries. The management of wounding in chimpanzee colonies is influenced more by the sex and rearing composition of a colony.

Injury risks among chimpanzees in three housing conditions

Meeting the psychological needs of chimpanzees (Pan troglodytes) can be a challenge given their aggressiveness on the one hand and the complexity of their social lives on the other. It is unclear how to balance the need to provide opportunities for species-appropriate behavior against potential risks of injury chimpanzees may inflict on each other. This study evaluates the suggestion that simpler social environments protect chimpanzees from wounding. Over a two-year period all visible injuries to 46 adult males, 64 adult females, and 25 immature chimpanzees were recorded at the Yerkes Regional Primate Research Center. Approximately half of the subjects were mother-reared, and the rest were nursery-reared. Housing included compounds containing about 20 chimpanzees, interconnected indoor-outdoor runs for groups of up to 12 individuals, and smaller indoor-outdoor runs for pairs and trios. Annual wounding rates were calculated for serious wounds (extensive injuries and all those requiring veterinary intervention) as well as for minor wounds. Compound-housed chimpanzees incurred the highest level of minor wounding, but serious wounding levels were not affected by housing condition. Even with a period of dominance instability and elevated levels of wounding in one compound, compound chimpanzees were not injured more than those in smaller social groups over the long term. Nursery-reared females in moderate-sized groups were wounded more than mother-reared females. Also, nursery-reared males and females were wounded less often when paired with mother-reared companions. Overall, this study indicates that maintaining chimpanzees in pairs and trios would not be an effective means for reducing injuries. The management of wounding in chimpanzee colonies is influenced more by the sex and rearing composition of a colony.

Effective Feeding Enrichment for Non-Human Primates: A Brief Review

There is a growing awareness that non-human primates kept in zoos and laboratories deserve more species-appropriate stimulation because of their biological adaptation to a challenging environment.

Numerous attempts have been made to effectively emulate the gathering and processing aspects of natural feeding. Whole natural food-items, woodchips mixed with seeds, the puzzle ceiling and the puzzle feeder stocked with ordinary biscuits, cost little or nothing but induce sustained food gathering and/or food processing. Turf and fleece substrates sprinkled with particles of flavoured food, foraging trays, probe feeders and puzzles baited with food treats also promote more foraging behaviour, but they are relatively expensive and require added labour time to load and clean them.

A Comparison of the Effects of Simple Versus Complex Environmental Enrichment on the Behaviour of Group-Housed, Subadult Rhesus Macaques

Enrichment of the environments of captive primates is currently of interest as both a basic and an applied research question, particularly when social and inanimate enhancements are used simultaneously. We measured the behavioural effects of two intensities of inanimate enrichment on 12 unimale-multifemale groups and 12 all-male groups from three cohorts of three to four-year-old rhesus macaques (Macaca mulatta). Half of the groups received a simple, inexpensive enrichment programme while the other groups received a more complex and costly combination of physical andfeeding enhancements. Observations were conducted on 93 subadults of both sexes during their initial year of group housing. Intensity of enrichment did not differentially affect the amount of time subjects spent in any of the activities analysed. Subjects that received the more complex programme spent only 8.3 per cent of their time using the extra enhancements. Therefore, there was little demonstrated benefit of the more costly enrichment programme. The three cohorts differed in the amount of time that they spent inactive, behaving agonistically, playing and located near a group mate. A planned comparison of one cohort that had been single-housed without visual access to social groups, to the two cohorts that had visual access to social groups during single caging, revealed differences in play and socially-located behaviour, which may have been due to differences in extra-cage conditions two years prior to the present study. When primates are housed socially with conspecifics as ‘social enhancements ‘, the relatively simple inanimate enrichment programme we used was as effective as the more costly programme. When enrichment resources are limited, inanimate enrichment efforts should be focused on monkeys that are not socially enriched.

The Effects of Different Types of Feeding Enhancements on the Behaviour of Single-Caged, Yearling Rhesus Macaques

Captive primates rarely have to spend as much time searching for, obtaining and processing food as do their wild counterparts. Enrichment techniques designed to encourage captive primates to spend more species-appropriate amounts of time in foraging behaviours have been successful. The present study measured the behavioural effects of four feeding enhancements: two devices (mats and puzzles) and two foods (produce and frozen juice), on four cohorts (n = 63) of single-caged, yearling rhesus macaques (Macaca mulatta). Devices required considerable manipulation to retrieve rewards, whereas enrichment foods required additional processing. Analyses compared periods when one of the enhancements was available to interim periods when no enhancements were available. Planned comparisons revealed that subjects spent more time feeding, and less time inactive, self-grooming, exploring and behaving socially when feeding enrichment was available. Significantly more time was spent feeding when enrichment foods were provided, but more time was spent playing and using enrichment when devices were in the cage. More time was spent self-grooming and exploring with the acrylic puzzle than with the artificial turf mat. Subjects spent significantly more time feeding when produce was available than when frozen juice was available. Feeding enhancements resulted in more species-typical patterns of activity for single-caged, yearling rhesus. Since feeding devices were used in species-typical activities in addition to feeding, devices may be more valuable than foods. Feeding enrichment programmes which combine stimulating devices with foods that are novel and require processing can positively affect the behaviour of captive primates.

Feeding enrichment and body weight in captive chimpanzees

Although positive behavioral consequences have been attributed to feeding enrichment, physiological changes may also occur. In this study, the body weight records of a large chimpanzee colony were reviewed to determine if body weight was affected by the implementation of a daily enrichment program, including food items offered three to four times per week. Comparing the mean body weight by age groups indicated that the weight of female chimpanzees was significantly greater after feeding enrichment but that male body weight did not differ.

A Grass Foraging Device for Captive Chimpanzees (Pan Troglodytes)

In the wild, chimpanzees spend most of their time foraging, so any device that stimulates this behaviour in captivity could potentially be effective enrichment. A simple grass foraging device constructed of a polyvinyl chloride (PVC) pipe cut in half lengthwise and planted with rye grass seed was designed to allow captive chimpanzees living in non-grassy enclosures to exhibit foraging similar to that of their wild counterparts. The grass containers were attached to the outside of six different enclosures. Observational data were collected on 14 adult chimpanzees (eight females, six males) within groups of either two or four members. A total of 54 hours of behavioural observations were conducted and comparisons were made across three conditions: baseline; grass container; grass container with extra foraging material (one half cup of sunflower seeds). Subjects used the grass container for 4.0 per cent of their time, but for 19.8 per cent of their time when the grass container with extra foraging material There was no statistical evidence of habituation to the device. Overall, the grass container only increased time spent foraging when it contained additional food items. Since behavioral benefits associated with this device are few, its potential application is limited.

Chimpanzees in AIDS research: a biomedical and bioethical perspective

The present article represents a consensus view of the appropriate utilization of chimpanzees in AIDS research arrived at as a result of a meeting of a group of scientists involved in AIDS research with chimpanzees and bioethicists. The paper considers which types of studies are scientifically justifiable in this species, the conditions under which such studies should be carried out, and the conditions which should be encouraged for post-experimental retirement of these animals.

An Enrichment Device for Great Apes

The influence of an environmental enrichment feeding device (puzzle feeder), on activity and behaviour patterns of captive orang-utans, gorillas and chimpanzees was studied at London Zoo. General activity levels and behaviours directed towards the feeder increased for all species when the feeder was filled with food Chimpanzees used the feeder significantly more (18% of observation periods) than either gorillas (10%) or orang-utans (9.4%). There was considerable individual variation of puzzle use by individuals within each group and time of day also affected use. In some instances abnormal behaviours were reduced. These results are discussed in relation to the management of captive great apes and it is suggested that the use of puzzle feeders can improve the welfare of these animals.

Comparing Two Manipulable Objects as Enrichment for Captive Chimpanzees

This study compared the effectiveness of kraft wrapping paper and rubber toys as enrichment for 22 chimpanzees group-housed in conventional indoor/outdoor runs. Objects were tested separately during 67 hours of data collection using a group scan sampling technique. Paper was used a mean 27 per cent of the available time, while the Kong Toys™ were used a mean 10 per cent of the available time. The degree of object manipulation and object contact was higher with the paper, but the level of social play and solitary play with the object was not differentially affected by the two objects. The objects had differing effects on the subjects’ levels of grooming, but affiliation, agonism, inactivity and sexual behaviour did not vary according to the object being used. A gender-by-age interaction was found, with immature males exhibiting the highest levels of solitary play with objects. Object use steadily declined over the first hour of exposure, showing evidence of habituation. Object use when the Kong Toy™ was present declined over the course of the study, but use of the paper remained consistent. Texture, destructibility, portability, complexity and adaptability may be important in determining the object's value as effective enrichment. The destructible wrapping paper was a more worthwhile enrichment object than the indestructible Kong Toy™ for the captive chimpanzees in this study.