There are potential advantages of housing primates in mixed species exhibits for both the visiting public and the primates themselves. If the primates naturally associate in the wild, it may be more educational and enjoyable for the public to view. Increases in social complexity and stimulation may be enriching for the primates. However, mixed species exhibits might also create welfare problems such as stress from interspecific aggression. We present data on the behavior of single and mixed species groups of capuchin monkeys (Cebus apella) and squirrel monkeys (Saimiri sciureus) housed at the Living Links to Human Evolution Research Centre in the Royal Zoological Society of Scotland's Edinburgh Zoo. These species associate in the wild, gaining foraging benefits and decreased predation. But Cebus are also predators themselves with potential risks for the smaller Saimiri. To study their living together we took scan samples at > or =15 min intervals on single (n=109) and mixed species groups (n=152), and all occurrences of intraspecific aggression and interspecific interactions were recorded. We found no evidence of chronic stress and Saimiri actively chose to associate with Cebus. On 79% of scans, the two species simultaneously occupied the same part of their enclosure. No vertical displacement was observed. Interspecific interactions were common (>2.5/hr), and equally divided among mildly aggressive, neutral, and affiliative interactions such as play. Only one aggressive interaction involved physical contact and was non-injurious. Aggressive interactions were mostly (65%) displacements and vocal exchanges, initiated almost equally by Cebus and Saimiri. Modifications to the enclosure were successful in reducing these mildly aggressive interactions with affiliative interactions increasing in frequency and diversity. Our data suggest that in carefully designed, large enclosures, naturally associating monkeys are able to live harmoniously and are enriched by each other.

Five domestic dogs (Canis familiaris) were tested in a cooperative exchange task with an experimenter, as previously tested in non-human primates. In the first task, the dogs exchanged to maximise payoffs when presented with food items of differing quality. All consistently exchanged lower-value for higher-value rewards, as determined by their individual food preference, and exchanges corresponded significantly with the spontaneous preferences of three dogs. Next, all subjects demonstrated an ability to perform two and three exchanges in succession, to gain both qualitative and quantitatively increased rewards (group mean = 72 and 92% successful triple exchanges, respectively). Finally, the ability to delay gratification over increasing intervals was tested; the dogs kept one food item to exchange later for a larger item. As previously reported in non-human primates, there was considerable individual variation in the tolerance of delays, between 10 s and 10 min for the largest rewards. For those who reached longer time lags (>40 s), the dogs gave up the chance to exchange earlier than expected by each subject's general waiting capacity; the dogs anticipated delay duration and made decisions according to the relative reward values offered. Compared to primates, dogs tolerated relatively long delays for smaller value rewards, suggesting that the socio-ecological history of domestic dogs facilitates their performance on decision-making and delay of gratification tasks.

Interaction with animals can be beneficial to humans and animal-assisted interventions (AAIs) are increasingly popular in a range of contexts. Dog training programs (DTPs) are the most popular form of AAI in custodial contexts; prisoners often have multiple needs and DTPs seem to facilitate a diverse range of positive outcomes, including improvements in well-being, behavior, and offending behavior. However, evidence on the efficacy of prison-based DTPs is still limited and these evaluations often lack detail or methodological rigor. We examined the experiences of male young offenders (N = 70) using thematic analysis of semi-structured interviews conducted following completion of a DTP. The themes that emerged indicated a broad range of inter-related experiences and positive outcomes. The most prevalent theme related to their experiences with Dogs (including feelings and attitudes), and there were perceived improvements categorized as: Positive Effects (including mood and well-being), Motivation, Charitable Purpose, Self-Efficacy, Improved Skills, Impulsivity, and Emotional Management. These themes mapped well onto outcomes previously identified in research on DTPs, and to the program’s core aims of improving behavior, educational engagement, employability, and well-being. The diversity and nature of these themes indicates that DTPs have considerable potential to engage and benefit those individuals with multiple needs, such as young offenders, and ultimately to achieve positive long-term outcomes with significant social, health, and economic impact.

Please e-mail h.m.buchanan-smith@stir.ac.uk for a personal copy of thsi article pubished in Applied Animal hence we argue that good enclosure design and husbandry is the most important factor in promoting positive interactions between individuals in mixed species groups. We conclude that long-term monitoring is important, and when combined with appropriate husbandry and enclosure upkeep, the welfare of individuals is enhanced in mixed species groups by the presence of other species.