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.

This study demonstrates that only a minimal time investment was needed to train a large troop of laboratory non-human primates to co-operate in the catching procedure. A group of 45 rhesus macaques (Macaca mulatta) was trained to enter a chute system voluntarily and be caught one by one. The total duration of the training sessions was under six hours, with less than 15 total work-hours invested by three people. The result was an improved capture procedure which minimized risk to personnel and distress to the animals.

Provision of adequate space for captive animals is essential for good welfare. It affects not only their behaviour but also determines whether there is sufficient room for appropriate environmental enrichment. Most importantly, appropriate cage size permits captive animals to be housed in socially harmonious groups and to fulfil their reproductive potential. For animals used in the laboratory, the environment can be an additional source of suffering and distress. If they can be better housed and cared for to reduce the overall impact of experiments upon them, then we are obliged to do so for ethical, legal and scientific reasons. Practically all current guidelines specify minimum cage sizes for laboratory primates based on unit body weight. We believe that no single factor is sufficient to determine minimum cage sizes for primates, and that instead a suite of characteristics should be used, including morphometric, ecological, social and behavioural characteristics. Here we explore the relevant differences between tamarins (Saguinus labiatus and S. oedipus) and marmosets (Callithrix jacchus) that have a bearing on setting minimum cage sizes. These include: body size; arboreality and cage use; home range size, mean daily path length and stereotypic behaviour; breeding success in the laboratory; and species predisposition and aggression. We conclude that it is even more important to provide tamarins with a good quantity of space in the laboratory than it is marmosets if well-being and breeding success are to be maximised.

Awareness of the self and awareness of others are difficult faculties to define. Part of the problem lies in the wide range of abilities that involve various aspects of awareness. Some of the most commonly studied abilities focus on the self-awareness of the individual. These abilities range from the capacity to distinguish self from non-self to the competency to reflect on one's past, present or future condition. Another set of abilities that is relevant to the study of awareness involves the interactions of individuals, and includes behaviours such as deception and empathy. We explore the possibility that species other than humans engage in deception and empathy, and consider the implications of such behaviours for self-awareness and other-awareness in these species. Although examples from a variety of species are provided, many examples come from dolphins and whales. This reflects both the authors’ interest in these animals and the possibility that large-brained creatures are more likely to engage in deliberate deception and/or true empathy.

Primates are highly social animals and appropriate enrichment is required to ensure their psychological well-being. Mirrors are sometimes used as social or sensory environmental enrichment. In this paper we investigate the suitability of mirrors as enrichment for captive primates, by reviewing the literature on mirror implementation in captive primate environments. Mirror-directed responses are mainly social as the mirror self-image is often seen as a conspecific. Although positive exploration and affiliative behaviours are observed, negative aggressive behaviours towards the mirror are most frequently recorded, and abnormal behaviours in primates do not decrease in mirror-enriched environments. There appear to be differences in habituation rates to mirrors amongst primates. While habituation to enrichment is generally perceived to be undesirable, this criterion should not apply when mirrors elicit negative behaviours. Primates that show mirror self-recognition, which are mostly great apes, may be best suitable for mirror enrichment, as they do not perceive the mirror self-image as a threatening conspecific. Increasing the understanding of the reflective properties of a mirror might help primates to understand that the image in the mirror is not real. This could be attained by using small, mobile mirrors. We suggest that mirrors can make decent primate enrichment if the primate understands its reflective properties, which should be evaluated on an individual level. Appropriate use of mirrors as sensory enrichment can improve primate well-being and prevent suffering.

The influence of several factors on abnormal behaviour was investigated in 46 singly housed sooty mangabeys (Cercocebus atys) (eight nursery-reared, 38 mother-reared), including self-injurious, self-directed, stereotypic locomotion, and faeces/urine-related behaviours (SIB, SDB, SL, FUR, respectively). An analysis of behavioural assessments spanning a mean of four years per subject showed that 83% displayed at least one form of AB during that time, with SL being the most common (mean of 3.06% of observation sessions and displayed by 59% of subjects) and SIB the least common (mean of 0.09% of all observation sessions and displayed by 20% of subjects). Like other primate species, displaying AB was influenced by the percent of life spent singly housed and by nursery-rearing during infancy. However, unlike some other primates, there was no influence of the number of yearly sedations or room relocations on AB; also, females were more likely to display AB than male mangabeys. To investigate the effects of nursery-rearing further, we compared the eight nursery-reared, singly housed subjects with eight nursery-reared subjects that were socially housed since the age of three years. While nursery-reared subjects in single housing displayed SL and FUR in higher proportions than those in social housing, subjects from both environments displayed SIB and SDB in equal proportions, suggesting that they are persistent forms of AB for nursery-reared mangabeys even after long-term social housing. To reduce future incidence of AB in captive mangabeys, we recommend minimising nursery-rearing and the duration of single-housing whenever feasible or avoiding them altogether.

During capture, in order to separate him from a possessive adult female and return him to his mother, a newborn male in a laboratory group of Cebus capucinus monkeys was found to have a seriously infected compound fracture of the humerus associated with a deep and extensive slash wound. Amputation of the affected limb was deemed necessary. Shortly after surgery the newborn was returned to his mother, in isolation from the group, with periodic removal for post-surgical care. Three weeks later the mother-newborn pair was returned to the social group and no further intervention occurred. Regular observations revealed mutual behavioural adjustments to the handicap by the mother and newborn. Compared to a normal age-mate, the amputee received more positive social attention from the mother and other group-members. Despite his showing delays in locomotor and manipulatory activities, the handicapped infant showed good behavioural progress. Early resocialization thus appears feasible following emergency surgery in newborn primates.

Non-human primates occasionally exhibit behaviours thought to occur only in captivity that are considered abnormal. In particular, hair-plucking behaviour occurs across many species of mammals and birds. This study was the first to assess the phenomenology, demography and aetiology of this behaviour in captive gorillas across the Association of Zoos and Aquariums (AZA) population. A survey was sent to 52 AZA institutions housing western lowland gorillas. Hair-plucking behaviour occurred in 15% of the surveyed population with 62% of institutions housing a hair plucker. Individuals were most likely to self-pluck using their fingers. Individuals that were exposed as youngsters to a hair-plucking group member were significantly more likely to develop the behaviour themselves. There was also a trend toward solitary individuals being more likely to perform this behaviour. Future research needs include identifying hormonal correlates to this behaviour, understanding its relationship to acute or chronic stressors, and examining what causes this behaviour to fluctuate in frequency once it has developed.

One commonly used method of managing confiscated wild primates in Latin American countries is to release rehabilitated individuals back to their natural habitats. However, little information has been collected from confiscated animal releases, so no clear guidelines have been developed to measure the success of this type of procedure. In most countries, the collection of critical post-release data is too costly and time-consuming for it to be incorporated into the routine procedures of institutions managing confiscated fauna. Therefore, this project was carried out in conditions similar to those of other Colombian and Latin American rehabilitation centres. A group of eight confiscated and rehabilitated brown capuchin monkeys (Cebus apella) was released in Los Llanos Orientales in Colombia, and monitored for 6.5 months to determine their adaptation and survival after release. Results were analysed according to how the animals adapted to their new environment in terms of foraging, feeding, locomotion, sleeping, social interactions between the group and with other animals and species, prédation, orientation, and establishment of a territory. The results show that the short-term adaptation and survival of the group 6.5 months after release was successful. Five of the eight animals remained together, two separated, and only one was lost during the first month. Implications for animal well-being are discussed.

It is widely agreed that all animals are entitled to some degree of welfare consideration, but that some are entitled to more consideration than others. However, the basis for singling out some animals for special consideration often seems to be mostly a matter of degree of similarity to, or association with, humans. A more reasonable criterion would involve the extent of suffering caused by given events. Two variables that seem likely to be very important in the extent of suffering are the capacity to anticipate and the capacity to recall. Everyday experience tells us that human suffering can be hugely amplified by either anticipation or recall of painful or distressing events. In the past, psychologists have tended to take the view that both these processes depend on the possession of language, and were therefore irrelevant to species other than humans. But comparative psychologists are increasingly making use of concepts from human cognition, including both memory and anticipation, to explain animals’ responses to both past and future events. These processes are invoked to explain the behaviour of a wide range of vertebrate species. Recent work on primate cognition indicates that more elaborate forms of representation may be possible in the great apes. Such evidence should be used as the basis for deciding whether to give special welfare consideration to certain species which have special cognitive capacities — or indeed enhanced welfare consideration to a wider range of species, if their cognitive capacities are found to be more sophisticated than is generally assumed.

It is imperative to provide adequate quantity and quality of space for all captive animals. Yet practically all guidelines on the housing of primates in the laboratory specify minimum cage sizes based solely on body weight. We argue that no single factor, such as body weight, is sufficient to determine cage size. Instead a suite of characteristics should be used that include morphometric, physiological, ecological, locomotor, social, reproductive and behavioural characteristics. Ideally, the primate's age, sex and individual history should also be taken into account. In this paper we compare this suite of characteristics for some commonly used primates whose weights overlap, to illustrate important differences amongst them. For good animal welfare and good quality science it is necessary to be sensitive to such species differences when determining suitable cage sizes.

The welfare of non-human primates used in scientific research must be safeguarded to promote scientific validity and for ethical reasons. Welfare can be improved by the refinement of practice, particularly if these refinements are applied to every aspect of the life of an animal used in the laboratory, from birth to death with the aim of both minimising harm and maximising well-being. Many refinement methods have been described in nationally and internationally accepted guidelines on laboratory practice, but awareness of these guidelines is not universal. In Part I of this review, we examine the influence of humans on non-human primates and summarise and evaluate methods of refinement that are or could be used to reduce suffering and improve welfare. In particular we focus on staff selection, education and training, human–animal bonds, staff communication, and training primates. In Parts II and III, refinements of housing, husbandry and experimental procedures are reviewed.

The stressful effects that environments have on farm and laboratory animal welfare are likely to depend on how much animals understand of the behaviour and intentions of their conspecifics as well as on their understanding of their physical environment. However, studies on animal social cognition have primarily focused on primates. Here, we report on our work on social cognition in domestic pigs. It focuses on the ability of domestic pigs to assess and use to their advantage the behaviour of conspecifics, and uses approaches pioneered in studies on primates. Our work has shown that dominant pigs use the privileged knowledge of a subordinate to their own advantage in a competitive foraging situation. While such exploitative behaviour is likely to be based on rapid learning about the subordinate ‘s behaviour, it is also possible that ‘higher’ cognitive abilities such as visual perspective taking could be involved. Ongoing work uses an adaptation of the Guesser-Knower paradigm to test whether pigs are indeed capable of visual perspective taking.

One aim of environmental enrichment techniques is to replicate ‘wild-like’ behaviour in captivity. In this study, three captive troops of Sulawesi crested black macaques (Macaca nigra) were each observed for 100 h in large naturalistic enclosures. Activity budgets constructed from these observations were compared with published data collected from wild troops in the DuaSudara Nature Reserve, Sulawesi (O ‘Brien & Kinnaird 1997). No significant difference was found between the activity budgets of the wild and the captive macaques, although social, resting and feeding behaviours were significantly different between zoos. There was more rest and less movement and feeding in captivity, although these differences were not significant. The relatively large number of individuals, the wide variety of age-sex classes and the large and complex naturalistic enclosures provided for them may have been important factors in promoting wild-like behaviour. This study shows that captive primates can exhibit wild-type activity budgets.

Captive primates are usually fed on monkey chow, a high-energy food designed to provide a complete and balanced diet for primates. In addition to the nutritional value of a food, its palatability, frequency of presentation in the daily diet and sensory stimulation may also be important for determining whether it is accepted by the animals. The aim of this study was to evaluate the food preferences of 26 captive capuchin monkeys (Cebus apella) using monkey chow and a variety of foods, which ranged from being very familiar to completely novel to the monkeys, and to assess whether the frequency of presentation in the daily diet and sensory stimulation affected their food preferences. Food preferences were scored in terms of the food item chosen and whether it was then eaten. In Experiment 1, subjects encountered paired combinations of seven familiar foods (present in the monkeys' diet with different frequencies), including monkey chow. In Experiments 2 and 3, monkey chow was paired with seven novel foods (not previously present in the monkeys' diet) and seven ex-novel foods (previously only encountered repeatedly during an earlier experiment) respectively. The results show that monkey chow, despite its high energy content, was not very attractive to capuchin monkeys. Other familiar foods (especially those not presented daily) were chosen and eaten more frequently than the monkey chow, and novel foods were chosen more frequently than the monkey chow. The findings of this study have implications for the feeding husbandry of captive primates. Familiar foods presented in the diet each day are less preferred; therefore good practice would be to alternate foods over time. Occasional presentation of novel food items could be a stimulating and economical method of providing sensory enrichment.

In order to safeguard the welfare of laboratory-housed non-human primates, refinement techniques should be applied to every aspect of the life of animals used in the laboratory, from birth to death, with the aim of both minimising harm and maximising well-being. In this second part of a three-part review we summarise published information on housing and husbandry practices, and describe ways to minimise contingent inhumanity associated with the use of primates in laboratories and their breeding and supply (where inhumanity is defined as the infliction of distress). We also discuss methods by which the welfare of these animals can be maximised on a day-to-day basis. The principles of enrichment, aspects of the housing environment, social and physical enrichment and acquisition are discussed. Refinement of the influence of humans and experimental procedures are discussed in Parts I and III of this review, respectively.

The social behaviour, ranging, and stereotypic behaviours of four red ruffed lemurs (one female, three males) was observed during group formation and release into a 2.25ha natural habitat enclosure at the Duke University Primate Center (DUPC). The female was immediately dominant to all males and there was no female-male affiliation during the initial stages of group formation. The group became identifiable as a unit after release to free-ranging when affiliation and group vocalizations began. Affiliation and vocalizations continued during subsequent recagings. Male dominance rank reflected relative age, but was subject to reversals. The stresses involved in release and group formation, however, can temporarily produce new aberrant behaviours which are soon replaced by normal behaviours. Once released into the large enclosure, stereotypic behaviours became infrequent but did not disappear. Other novel behaviours such as catatonic huddle and all male huddles were observed during release. Natural habitat enclosures can be important tools in the psychological well-being of captive primates.

Published information provides scientific evidence that traditional, involuntary restraint techniques of research non-human primates are intrinsically a source of distress resulting from fear. It has been documented that common methods of enforced restraint result in significantly increased adrenal activity as well as significant changes in a variety of other physiological parameters. There is no scientific evidence that the animals adequately habituate to involuntary restraint. Numerous reports have been published demonstrating that non-human primates can readily be trained to cooperate rather than resist during common handling procedures such as capture, venipuncture, injection and veterinary examination. Cooperative animals fail to show behavioural and physiological signs of distress. It was concluded that the advantages of training techniques over traditional restraint techniques will have to be explored more extensively in the future for the sake of research subjects and scientific methodology.