The early days of the Covid-19 pandemic were an unprecedented time at the Detroit Zoo. When the Zoo closed as part of a statewide lockdown in March 2020, the absence of visitors was palpable. Walking the grounds in the budding spring weather, it was eerily quiet, the usual sounds of school groups and families replaced by birdsong and the hum of traffic outside the Zoo. The Zoo is usually open to guests 362 days of the year, and we realized that this sudden quietus was an opportunity. We had a chance to understand how animals experienced life at the Zoo in the absence of visitors—not just for a night or a holiday but, potentially, for months.

Being around human visitors is a defining feature of life for animals in zoos and aquariums. For this reason, visitor effects are an important topic in the study of animal welfare, which is the science investigating the physical, behavioral, and mental lives of animals to understand how they are faring overall. Animal welfare scientists try to understand life from the animals’ perspective. In this case, we wondered, what did the animals think when the crowds suddenly disappeared? Some people might assume that animals enjoy people watching, while others might suspect that visitors can be an annoyance. The scientific literature on visitor effects supports both ideas. Studies show that visitors can have a positive, neutral, or sometimes negative effect on animals living in zoos and aquariums. How would the residents of the Detroit Zoo respond?

Researchers at the Center for Zoo and Aquarium Animal Welfare and Ethics (CZAAWE) asked this question by collecting data on the behavior, use of space, and (in some cases) hormone levels of animals across the Zoo. For most projects, we collected data for about a month while the Zoo was closed and for another month after reopening. We monitored red pandas, southern white rhinoceroses, trumpeter swans, red kangaroos, red-necked wallabies, Catalina Island rattlesnakes, European glass lizards, beaded lizards, Arrau turtles, dwarf caimans, and a spiny-tailed iguana. We quickly realized that one challenge of this research was that the animals were very attentive to the sudden change in visitor patterns. They were alert to our activities, so we put our binoculars to good use, conducting our observations from a distance and hoping not to influence the behaviors we were recording.

The results of our research were as diverse as the creatures we studied. The iguana used more of his habitat when the Zoo was open, and both rattlesnakes were more active when the Zoo was open as well. However, the glass lizards spent more time hiding after the Zoo reopened. They were also more likely to be not visible when visitors were tapping on the glass of their enclosures, demonstrating an important point. Actions taken to get a response from animals might seem innocent, but imagine if someone was pounding on the door to your house all day—you might hide too. It shows that we all have a collective responsibility for the welfare of animals at the Zoo.

Although we saw differences in behavior with the Zoo open and closed, it was often unclear whether those changes represented a difference in overall welfare. The red kangaroos were an interesting example. We chose to study them because their walk-through habitat can potentially put guests in proximity to them. We found that in response to visitor presence, the kangaroos changed their schedule so they utilized the area around the visitor path more frequently in the morning, before visitors reached their habitat. However, there were no signs that this change impacted their overall well-being. Of course, by the time the Zoo reopened, we were transitioning from spring to summer, so we cannot rule out the possibility that warmer temperatures played a role in these trends. This example shows the complexity of studying human-animal relationships in the Zoo, as the effects of visitors can be difficult to isolate from other seasonal or environmental changes. A year later, we are still combing through the piles of data we collected during the statewide lockdown. Our results have shown many behavioral differences when the Zoo was closed versus open, but most of the effects were quite subtle. It is possible that the return of visitors at lower than normal capacities might have affected the results. The Zoo’s welfare-focused habitat designs, which give animals choices about whether or not to be seen and where to spend their time, may also make animals feel comfortable in their living spaces whether or not visitors are present. Using science, we can continue to investigate these important questions as part of a comprehensive approach to ensuring animals at the Detroit Zoo thrive.

– Dr. Grace Fuller is the director of animal welfare for the Detroit Zoological Society.