The presence of human visitors has been shown to affect the behaviour of several different mammalian species in a number of different zoos, but the behavioural changes observed are not always consistent with a simple ‘stressful influence’ explanation. Data for non-primate species are too sparse to draw meaningful conclusions; but for primates, the evidence reviewed in this paper allows several hypotheses to be tested. Neither a social facilitation nor an audience attraction hypothesis can be generally supported by the available studies. However, these studies are consistent with a general stressful influence hypothesis, although the extent of this influence is itself affected by other variables, notably species and housing differences. There is some evidence that chronic exposure to human audiences may lessen this stressful influence in some species; and in certain circumstances (notably where some members of the public throw food) the effect of the audience is almost an enriching one.

The Indian rhinoceros or greater one-horned rhino (Rhinoceros unicornis) is listed as vulnerable by the IUCN Red List of Threatened Species and, therefore, captive individuals have been subject to the European Endangered Species Programme since 1990. Enhancement of welfare is key in ensuring the breeding success of this species in captivity. Salivary cortisol has been recently used to assess welfare of captive and free-ranging animals. Nevertheless, rhythms of cortisol secretion may fluctuate throughout the year and therefore, knowledge of the circannual pattern of cortisol secretion is essential to evaluate the physiological significance of seasonal variations of cortisol levels as an indicator of stress in animals. Here, we analyse monthly differences in cortisol secretion in two Indian rhinoceros. Saliva samples of two rhinoceros were collected and analysed by radioimmunoassay for the period of one year to determine cortisol concentrations. We found a seasonal pattern of salivary cortisol secretion. The highest cortisol concentrations were found in August and decreased until reaching a nadir in January. Cortisol concentrations in these two animals showed a correlation with temperature and visitor numbers but it is not possible to draw conclusions from this study as to whether the variation in cortisol was due to these or other factors.

The relationship between zoo animals, particularly nonhuman primates, and visitors is complex and varies by species. Adding complexity to this relationship is the trend for zoos to host events outside of normal operating hours. Here, we explored whether a late-night haunted-house style event influenced the behavior of spider monkeys. We conducted behavioral observations both on event nights and nights without the event. The spider monkeys were active and outside more frequently on event nights compared to the control nights indicating that their typical nighttime behavior was altered. However, it is difficult to definitively conclude whether the behavioral changes were a result of the event being aversive or enriching. Our findings suggest that zoos should conduct behavioral observations of and collect physiological data from their animals, especially if they are sensitive to environmental changes, when implementing new events, including those occurring outside of normal operating hours to ensure high levels of animal welfare.

Modern zoos utilise a variety of education tools for communicating with visitors. Previous research has discussed the benefits of providing multiple education communications, yet little research provides an indication of what communications are being employed within zoos today. This research is a two-phased, mixed-methods investigation into the communication between zoos and their general visitors. Phase 1 involved an online questionnaire to which 176 zoos from 50 countries reported on the types of education communications they typically use for their general visitors. The second phase comprised nine zoo case studies, enabling direct observation and face-to-face interviews on site with zoo staff and zoo visitors. The findings of this research provide a snapshot of education communications offered to zoo visitors, and indicate that zoo exhibit signage remains the most prevalent medium. The findings further indicate that 95% of visitors read at least some exhibit signs and that more than 70% of participating zoos utilise person-to-person education. The implications of these findings for improving zoos’ educational communication are discussed.