Husbandry training and environmental enrichment are both important advancements associated with current behavioural welfare practices. Additionally, the use of training procedures has been proposed as a form of enrichment, with the implication that training can produce beneficial behavioural welfare results. This paper examines the concept of training as enrichment through three distinct ways training procedures could enrich: (i) training facilitates enrichment usage; (ii) training modifies interactions, conspecific or otherwise; and (iii) training expands behavioural repertoires. Within each category, the paper focuses on past research that provides empirical support for training functioning as enrichment, as well as related areas of research that provide additional evidence. Previous studies support the claim that training is enriching, with additional research necessary to better understand how prevalent and under what conditions training procedures function as enrichment. Future training research should examine these potential enrichment effects, including methodology that allows for comparisons to traditional enrichment, the use of welfare diversity/variability indices, and the effects of learning on trainers and trainees alike.

The success of breeding primates in captivity has led to a surplus number of animals in collections. This review examines published journals and key books to investigate the various methods of primate population control. Hormonal, surgical and separation methods are discussed and evaluated with regards to behavioural and welfare implications. Methods of dealing with surplus animals are also reviewed. It is concluded that the successes of contraception methods vary significantly between species, and in some cases not enough is known to conclusively state that one method is preferable to another. The behavioural effects of contraception should be evaluated, as social status and sexual behaviours can be negatively affected by contraception. Non-reversible sterilisation methods, such as castration, should not be used without thorough evaluation due to the behavioural effects on the individual and group as a whole. Overall, the zoo community should share information of successes and failures of contraception in different species, and professional advice should be sought to ensure that the welfare of primates in captivity is not compromised.

Accurate identification of key welfare issues for captive elephants could improve standards and help in the development of a welfare index. In the absence of adequate scientific information on the relative importance of key issues, the views of a range of stakeholders were sought using adaptive conjoint analysis. Fifteen key welfare issues were identified by experts, and three to six Levels of each, representing common husbandry practices. In order of declining importance, 224 stakeholders rated the issues as enclosure substrate > group size > healthcare > enrichment > chaining > enclosure type > exercise provision > enclosure size > interaction with keeper > enclosure environment > keeper knowledge/experience > diet > contact method with keeper > display duration > enclosure security. Enclosure size was considered more important by scientists and keepers than zoo directors/managers and animal welfare organisation representatives. Animal welfare organisation representatives rated enclosure security higher than scientists. Keeper husbandry methods and ability of elephants to be active were two principal components in responses. Three principal groups of respondents were identified: scientists/veterinarians focusing more on conditions for the elephants and less on interaction with the public; keepers, focusing on keeper contact method, feeding and knowledge of elephants; and a group with mainly animal welfare organisation representatives/zoo directors focusing on enclosure security. It is concluded that there are some differences between stakeholders in their recognition of the most important welfare issues for elephants in zoos. However, recognising that a diversity of informed opinion is necessary to adequately devise welfare standards, an index of elephant welfare in zoos is proposed, based on the relative merits of different husbandry practices and the importance of the different issues.

It is commonly assumed that animals suffer if they cannot perform behaviours seen in wild conspecifics. Although comparisons with the behaviour of wild conspecifics are a popular method of assessing the welfare of captive animals, their validity has not been fully assessed. Homeostatic models of motivation suggest that many behaviours are stimulus driven rather than internally generated. Thus, it is possible that the non-performance of some wild-type behaviours does not necessarily compromise animal welfare, unless welfare is defined as being compromised by such non-performance. The flexibility of wild animal behaviour and the fact that animals free to perform the complete range of wild behaviours can suffer, must also put into the question the validity of such comparisons. Technical criticisms also arise when one considers the difficulty of constructing accurate and unbiased time budgets for wild animals. It is possible that the expressions of wild-type behaviours correlate with enhanced welfare, rather than cause enhanced welfare. Thus, if the consequences of behaviour are more important than the expression of behaviour itself, environmental enrichment does not necessarily need to rely upon the performance of wild-type behaviours for the improvement of animal welfare. Therefore, although behavioural comparisons with wild animals can be considered as potentially useful indicators of behavioural differences, they cannot always be relied upon to give an objective assessment of animal welfare. To make an assessment of welfare, behavioural comparisons with wild animals should be used in conjunction with other techniques to demonstrate that the consequences of non-performance of wild behaviours results in impoverished welfare.

The COVID-19 pandemic led to unprecedented lockdowns with rippling impacts on the lives of humans and animals alike. Since zoos were among the first institutions to close during the pandemic, the lockdowns presented the opportunity to conduct a natural experiment examining the relationship between visitor presence and the welfare of zoo-housed animals. In this study, we assessed the welfare of six Sumatran orangutans (Pongo abelii) at Toronto Zoo both during and following the pandemic lockdowns. We compared behavioural and physiological indicators of welfare during a lockdown and after visitors were reintroduced. Specifically, if the orangutans’ welfare was affected by the visitor re-introduction phase we predicted there would be an increase in the following measures: (1) use of exhibit areas away from visitors; (2) behavioural measures (hiding, self-directed behaviours, agonistic behaviours, agitated movement, and idiosyncratic object-directed behaviours [head slamming, and fabric tearing]); and (3) physiological measures (faecal consistency and glucocorticoid metabolites) when compared to the lockdown. We also measured changes in activity levels such as foraging and inactivity. We found that orangutan exhibit space use did not change when visitors were reintroduced. In fact, the orangutans hid less when visitors were introduced than during the lockdown. Foraging, inactivity, and other behavioural indicators of stress did not change when visitors were introduced. Similarly, neither faecal consistency nor glucocorticoid metabolites changed across the study phases. Our data show that visitor re-introduction did not negatively affect the welfare of the Toronto Zoo orangutans. However, the presence of keepers was found to affect the behaviour of the orangutans and warrants further study.

The influence of visitors on the welfare of captive animals, known as the visitor effect, may in some instances be stressful, adversely affecting animal health. Although the survival of many felid species depends on captive breeding programmes, little is known about this effect. A better understanding of the visitor effect is required to ensure the well-being of felids and the success of breeding programmes. We sought to determine whether the presence of visitors affects behaviour patterns and space use in five feline species in two Spanish zoos: Eurasian lynx (Lynx lynx), jaguar (Panthera onca), bobcat (Lynx rufus),ocelot (Leopardus pardalis) and Asiatic lion (Panthera leo persica) and, if so, whether the effect on animal welfare is positive or negative. To our knowledge, no previous research has addressed the visitor effect in these species, with the exception of the jaguar. Data on animal behaviour, enclosure use, and visitor density were collected during the spring and summer of 2011 and 2012. Changes were observed for all studied species when the zoo was open to the public: four species devoted less time to complex behaviour (ie play, walk) and spent more time resting; ocelots and bobcats made more use of hidden spaces and less use of areas closer to visitors, while the jaguar tended to do the opposite. No correlation was found between visitor density and animal activity, indicating that animals are affected by the mere presence of visitors, regardless of their number. Our findings are in line with those reported by other authors, who have suggested that these behavioural changes are linked to chronic stress. Visitor effect was classed as negative for the welfare of all studied species apart from the jaguar. We advocate the need for future research into potential solutions to mitigate the adverse effect of visitors on felids.

Animals under human care are exposed to a potentially large range of both familiar and unfamiliar humans. Human-animal interactions vary across settings, and individuals, with the nature of the interaction being affected by a suite of different intrinsic and extrinsic factors. These interactions can be described as positive, negative or neutral. Across some industries, there has been a move towards the development of technologies to support or replace human interactions with animals. Whilst this has many benefits, there can also be challenges associated with increased technology use. A day-long Animal Welfare Research Network workshop was hosted at Harper Adams University, UK, with the aim of bringing together stakeholders and researchers (n = 38) from the companion, farm and zoo animal fields, to discuss benefits, challenges and limitations of human-animal interactions and machine-animal interactions for animals under human care and create a list of future research priorities. The workshop consisted of four talks from experts within these areas, followed by break-out room discussions. This work is the outcome of that workshop. The key recommendations are that approaches to advancing the scientific discipline of machine-animal interactions in animals under human care should focus on: (1) interdisciplinary collaboration; (2) development of validated methods; (3) incorporation of an animal-centred perspective; (4) a focus on promotion of positive animal welfare states (not just avoidance of negative states); and (5) an exploration of ways that machines can support a reduction in the exposure of animals to negative human-animal interactions to reduce negative, and increase positive, experiences for animals.

Human evaluation of animal emotional expressivity can inform animal welfare. Qualitative Behavioural Assessment (QBA) has been applied to domesticated and some non-domesticated animals, but its use in primates is limited despite their emotional expressivity. We aimed to develop and apply a QBA for bonobos (Pan paniscus) through two consecutive studies. We applied Free Choice Profiling (FCP) and the Fixed List methodology, respectively, in Study 1 and 2, and invited students and bonobo experts to rate video clips of zoo-living bonobos of different sexes and age classes, and before and after moving to a new enclosure. In Study 1, students described dimension 1 as ranging from ‘quiet/calm’ to ‘angry/active’ and dimension 2 from ‘sad/anxious’ to ‘happy/loving’. Experts described dimension 1 ranging from ‘quiet/relaxed’ to ‘nervous/alert’ and dimension 2 from ‘nervous/bored’ to ‘playful/happy’. Using a fixed list of descriptors, informed by findings from Study 1, students in Study 2 described dimension 1 as ranging from ‘quiet/calm’ to ‘agitated/frustrated’, and dimension 2 from ‘sad/stressed’ to ‘happy/positively engaged’. Experts described dimension 1 as ranging from ‘quiet/calm’ to ‘active/excited’, and dimension 2 from ‘sad/bored’ to ‘happy/positively engaged’. Students scored adults as more ‘calm/quiet’ and experts scored subadults as more ‘happy/positively engaged’. Additionally, experts in Study 2 rated bonobos as more ‘active/excited’ in their new enclosure. Reliability was moderate to good for the dimensions. Additionally, animal-directed empathy of observers influenced QBA scores. This is the first time, FCP has been successfully used as a method to study primate emotional expressivity. Our findings show the promise of employing QBA in primate studies and in industry, with validation of additional metrics to enable its use for welfare-monitoring purposes.

Zoo- and anthropomorphism may both be scientific heresies but both may serve as a basis for thought (and real) experiments designed to explore our ability to assess quality of life as perceived by another sentient animal. Sentience, a major contributor to evolutionary fitness in a complex environment, implies ‘feelings that matter’. Strength of motivation is a measure of how much they matter. Since humans and most domestic animals share the property of sentience, it follows that some aspects of feeling may be similar, and where we differ, the differences may be of degree rather than absolute. One of the assumed absolutes that I shall challenge is the concept that non-human animals live only in the present. I explore how domestic animals may experience the feelings of hunger, pain, fear and hope. Hunger is indisputably a primitive sensation. Pain and fear are primitive sensations with emotional overtones. The problem is to discover how they may affect quality of life. Acute pain and fear are positive signals for action to avoid harm. These actions and their consequences (‘how well did I cope?’) will be committed to memory and affect how an animal feels when they recur, or it fears they may recur. Hope (and its antithesis, despair) are considered by many philosophers (who do not own dogs) as emotions restricted to humans since only we can imagine the future. However, by application of zoomorphism we may classify hope with hunger as a primitive feeling of dissatisfaction with the status quo. Either may lead to action directed towards the goal of feeling better or encourage the belief that things will get better (food will arrive). Both are feelings of expectation for the future modulated in the light of past experience. With all these four emotions quality of life may be expressed in terms of how well the animal feels it can cope, both in the present and in the future. When it feels it cannot cope, then it will suffer.

Lion (Panthera leo) cubs are used in wildlife interaction tourism but the effects on cub welfare are unknown. We assessed the behaviour of three cohorts of lion cubs, twelve animals in total, at three different interaction facilities, using continuous and scan-sampling methodologies for the entire duration of cub utilisation for human interactions. Cubs spent most time inactive (62%), particularly sleeping (38%), but also spent a substantial amount of time playing (13%) and being alert (12%). A generalised linear mixed model revealed that cub behaviour was similar in two facilities but different from cubs in the third. In these two similar facilities, as human interactions increased, the time spent resting, sleeping and playing with other cubs decreased, and alert behaviour, grooming of humans and flight responses increased. In the third facility, cubs had an abnormal activity budget, with high levels of inactivity (80%) accompanied by a lack of response to human interactions. We conclude that in some facilities normal cub behaviour cannot be achieved and may be compromised by a high frequency of human interactions, which therefore needs to be controlled to limit adverse effects on cub behaviour.

Anthropogenic noise has been related to stress in captive animals; despite this there have been few studies on animal welfare assessment in walk-through zoo enclosures. We aimed to investigate the behavioural effects of noise on a male-female pair of two-toed sloths (Choloepus didactylus), housed in a walk-through enclosure in a zoo in the UK. The animals were filmed for 24 h per day, during three days per week, including days with potential low and high flow of visitors, for three weeks. Sound pressure measurement was performed four times each collection day (twice in the morning, once at noon and once in the afternoon), for 15 min per session, using a sound level meter. The number of visitors passing the enclosure during each session was also recorded. The videos were analysed using focal sampling, with continuous recording of behaviour. Correlations between noise and the behaviours expressed during, and in the 24 h after the acoustic recording, were investigated. The number of visitors correlated with the acoustic parameters. At the moment of exposure, higher levels of noise correlated with decreased inactivity, and longer expression of locomotion and maintenance behaviours for the male; the female spent more time inside a box in these moments. During the 24 h hours after exposure to loud noise, the female showed no behavioural changes while the male tended to reduce foraging. The behavioural changes observed in both individuals have already been reported in other species, in response to stressful events. Our study indicates the need for a good acoustic management in walk-through zoo enclosures where sloths are housed.

In certain areas of South America, free-ranging, wild guanacos (Lama guanicoe) are exploited for fibre by local people. This activity includes the capture and handling of animals which can adversely affect their behaviour and physiology. This study investigated the behavioural and physiological responses of guanacos to shearing and handling activities in order to obtain a better picture of the welfare state of individuals. Parameters that were assessed consisted of: time enclosed; handling time; sex; age; and vital signs (heart beat frequency per minute, respiratory rate per minute, body temperature and body condition). Blood samples were also collected to measure serum cortisol levels and neutrophil/lymphocyte ratios. Frequencies of spitting, kicking, escape attempts and vocalisations were recorded as behaviours considered indicative of stress. Our results showed that stress behaviour frequencies were higher with increased handling time, whereas serum cortisol and N/L levels were higher when body condition scores were low. Handling time should be kept as short as possible to minimise individuals’ stress levels, particularly when body condition is low. Stress behaviour rates and serum cortisol levels were higher in juvenile compared to adult guanacos. Finally, both physiological measures of stress — serum cortisol concentrations and N/L ratios — were higher during the management activities of 2010 than in 2009, which may have been as a result of more inclement weather in 2010. When managing guanacos, it is important to consider both animal traits and previous environmental conditions and to avoid shearing juveniles and individuals with poor body condition scores if weather conditions are severe. These management recommendations are likely to improve animal welfare, facilitating sustainable management of this wild and emblematic species from the desert biomes of South America.

Primates are bred in captivity for a number of purposes, from zoo-based captive breeding programmes for conservation to breeding for biomedical research. In each case, breeding animals that are fit for purpose, either as viable candidates for reintroduction or as valid research models, has presented challenges and resulted in steep learning curves. The breeding of animals for biomedical research has become increasingly focused on the production of animals that are less stressed by captive (specifically laboratory) environments. This is because elevated, particularly chronic, stress responses can result in altered physiological, neurological and behavioural states that have the potential to compromise the validity of scientific results. Selective breeding in captivity to, for example, maximise production, select for docile temperament or specific genotypes for biomedical research, is likely to be counter to natural selective pressures for evolutionary fitness. Given that many natural selective pressures active in the wild are absent in captivity, this paper reviews the selective breeding of primates (especially Old World monkeys) in captivity, its potential negative effects, and options that exist for ameliorating these negative effects.

We estimate that stereotypies are currently displayed by over 85 million farm, laboratory and zoo animals worldwide. This paper investigates their reliability as welfare indicators, by surveying studies relating stereotypy to other welfare measures and by analysing the mechanisms underlying this behaviour. Where data exist, most (approximately 68%) situations that cause/increase stereotypies also decrease welfare. Stereotypy-eliciting situations are thus likely to be poor for welfare, although exceptions exist. Within such an environment, however, most (approximately 60%) accounts link individual stereotypy performance with improved welfare (cf approximately 20% linking it with reduced welfare). Thus, in a sub-optimal environment, non-stereotyping or low-stereotyping individuals could well have the poorest welfare, although again exceptions exist. Examining the mechanisms underlying stereotypy performance, we discuss four processes that could account for these complex links between stereotypy and welfare. Beneficial consequences from performing the specific source-behaviour of the stereotypy (‘do-it-yourself enrichment’), or arising from repetition per se (‘mantra effects’), may ameliorate welfare in poor environments. In addition, stereotypies that have become centrally controlled (habit-like), or that arise from autistic-like changes in the control of all behaviour (perseveration), are likely to be unreliable indicators of current state because they can be elicited by, or persist in, circumstances that improve welfare. To refine the role of stereotypy in welfare assessment, we suggest the collection of specific additional data to reveal when any of these four processes is acting. Until such research increases our understanding, stereotypies should always be taken seriously as a warning sign of potential suffering, but never used as the sole index of welfare; non-stereotyping or low-stereotyping individuals should not be overlooked or assumed to be faring well; simple measures of frequency should not be used to compare stereotypies that differ in age, form, or the biological or experiential characteristics of the performing animal; enrichments that do not immediately reduce stereotypies should not be assumed failures with respect to welfare; and finally, stereotypies should not be reduced by means other than tackling their underlying motivations.

Environmental enrichment by increasing foraging behaviour and providing food item choice are widely practised and generally accepted as effective methods for reducing stereotypic behaviour in captive animals. In this study, the effectiveness of increasing foraging patch choice and food item choice on reducing motor stereotypy in two captive vicugna were examined. For the purposes of the study, first, browse was added to the vicugna's enclosure as an additional forage item and, second, the vicugna's normal feed was divided: half being provided in the indoor quarters and half in the outdoor yard. The results revealed that providing browse as an additional forage item increased the observed stereotypic behaviour; however, dividing the vicugna's feed, and therefore increasing forage patch choice, decreased stereotypy. This study was limited because of the small sample size and because the area in which the vicugna were performing stereotypic behaviour was partially visually obscured. However, this study has implications for animal welfare because it highlights the need to evaluate the suitability of foraging enrichment items, and suggests that more research into accommodating the adaptive foraging behaviour of this species in captivity may be necessary.

Visitors to zoos are a source of potential stress to certain captive-housed animals. Much research has focused on Europe and America, whereas the effect of human audiences on the behaviour of captive animals in Chinese parks has so far not been investigated. Sika deer (Cervus nippon) housed in Zhu-Yu-Wan Park, Yangzhou City, Jiangsu Province, China, were studied to determine the effect of different visitor density levels on the animals’ activity. From June 21 to December 10, 2006, and again from February 21 to July 10, 2007, 21 subjects were observed for 10 h per week for a total of 44 weeks. Continuous focal animal sampling was used to quantify behaviours, and visitor density was recorded every minute. Friedman's tests were used to examine the effects of visitor density on the behaviour of sika deer. Results showed that high visitor density was significantly related to foraging, resting, watching and ‘non-visible’ behaviours. The findings demonstrate that high numbers of visitors have an effect on the welfare of sika deer.

Given the difficulties of conducting regular endocrine and veterinary assessments of animals, behavioural observations are often the most commonly used tool to assess the welfare of animals in human care. Behavioural measures, inexpensive and convenient to collect, also have their challenges, such as ensuring the behaviours of interest are reliable indicators of an animal's internal state. Welfare assessments include both positive and negative indicators, and a commonly used indicator of negative welfare is self-directed behaviour (SDB). SDB has been described as a behavioural indicator of stress through observation and experimentation; however, this pattern is not universal despite assumptions otherwise. The purpose of this study was to experimentally evaluate the use of SDB as an indicator of negative welfare in mandrills (Mandrillus sphinx) with the goal of understanding the function of SDB in relation to stress. Using a touchscreen-mediated cognitive task, the mandrills were observed to self-scratch significantly more often during incorrect than correct trials; however, rates of SDB did not vary between increasingly difficult testing conditions. The mandrills had individual variation in their use of body-shakes and yawns under negative and positive conditions that mirror similar variation observed in other primates. This study provides experimental evidence that self-scratching in mandrills can be used as a behavioural indicator of anxiety and that welfare assessments for animals in human care need to account not only for species’ differences, but also for individual differences.

Cross-institutional studies that combine non-invasive physiological measures of stress responses and the assessment of individual differences in behaviour and temperament have great potential as tools for assessing the well-being of zoo animals and for identifying key environmental stimuli relevant to well-being. In addition, such studies allow comparison of animals under a wide variety of conditions and enable researchers to obtain sufficiently large samples sizes for statistical data analyses. Faecal corticoid measurements, a method recently developed to monitor adrenal activity in wildlife and domestic species, can be obtained non-invasively as part of the normal husbandry routine. While basic techniques still need improvement, and interpretation of the acquired measures can be challenging, assessment of faecal corticoid concentrations can provide a useful indicator of stress responses under a variety of captive conditions. Here we report on three studies that illustrate this approach and the results that can be obtained. An on-going study reveals significant differences in the pattern of variability of faecal corticoid concentrations between polar bears that are reported by keepers to perform stereotypic behaviour and those that do not. In another study, faecal corticoid measures indicated that stress responses to certain extraneous noises might interfere with the breeding of Hawaiian honeycreepers in captivity. In a study of clouded leopards, higher faecal corticoid concentrations were measured when cats were kept on public display or near potential predators compared to individuals maintained off exhibit or in the absence of visible predators. The findings of an on-going experimental study suggest a causal relationship between the provision of additional hiding spaces and a decline in faecal corticoid concentrations in clouded leopards.

Visitors to zoos can be a potential source of stress to captive-housed primates, resulting in increased abnormal behaviour and intra-group aggression. Finding a way to screen primates from human visitors may be one method of decreasing stress and enhancing animal welfare. For this study, the behaviour of six zoo-housed gorillas was studied for one month during standard housing conditions (control condition) and for a further month following the installation of a camouflage net barrier to the viewing area of the exhibit (barrier condition). Visitors’ (n = 200) perceptions of the animals and the exhibit were also recorded during each condition. The net barrier had a significant effect on some components of the gorillas’ behaviour. The gorillas exhibited significantly lower levels of conspecific-directed aggression and stereotypic behaviours during the barrier than the control condition. The net barrier also had a slight effect on visitors’ perceptions both of the animals and of their exhibit. The gorillas were considered to look more exciting and less aggressive during the barrier than the control condition. The exhibit was also considered to be more appropriate for visitors following the introduction of the camouflage netting. Overall, the addition of a screen such as camouflage netting could be considered a positive change, resulting in a reduction in those behaviours typically induced by large groups of visitors and an improvement in public perceptions of the animals and their environment.