Sounds and Stressors: How Does the Air & Water Show Affect Zoo Primates?

August 15, 2023

The Chicago Air and Water Show is a traditional, much-loved event from the City of Chicago’s Department of Cultural Affairs and special events, featuring jet planes engaging in stunning displays formation-flying over Lake Michigan.

During the weekend of August 19-20 (with rehearsals on August 18), huge crowds of over a million spectators will take spots along the lakefront at places like Navy Pier, Museum Campus, and North Avenue and Oak Street beaches to view the free aerial excitement. There are lots of crowds—and there’s plenty of noise.

If you’re from Chicago, you know that Lincoln Park Zoo is right at the north edge of the best viewing of all the air and water show action. In fact, during that weekend, you’ll find many people parking in the official zoo lot to take advantage of its proximity to the sounds and sights of low-flying military and civilian aircraft over the weekend (in case you’re wondering, parking costs $70, but you can still get a prepaid spot for $60 if you sign up now through Eventbrite).

So how do the animals at the zoo react to the stunts by the U.S. Air Force’s Thunderbirds, the U.S. Army’s Golden Knights, and all the other performers that blaze by at super-fast speeds? Well, of course the scientists here have studied that.

Sound and the Show

Given that experts recommend human attendees wear earplugs—and also say that local residents should soothe their pets during the weekend—it’s only natural to wonder how all that high-octane noise affects the animals that live at the zoo. If you already know about the zoo’s commitment to data-backed animal welfare, you would not be surprised to hear that our researchers have looked into it already.

Research took place during the Chicago Air & Water Show in 2016 and 2017 to gauge how three primate species here—Japanese macaques, western lowland gorillas, and chimpanzees—reacted to the three days during which jets fly directly overhead in short, unpredictable bursts.

Basically, researchers took a baseline reading of the animals’ state of mind, following previous studies that showed both humans and primates react more slowly in touching certain images on a touchscreen computer (in this case, faces of other members of their species they did not know) when they are stressed. Then, they tested the primate subjects again during the three days of the airshow, when planes passed directly above animal habitats up to 80 times a day.

The researchers measured the sound levels near the animals as well—and found that in 2017, 14.6 percent of the 10-minute audio samples taken during the time period exceeded 90 decibels (with a maximum of 93.5). For comparison, 90 dB is similar to the noise level of a nearby leaf blower.

Data and Discovery

The researchers predicted that the macaques would experience anxious moods during the course of the weekend due to the startling noise of the jets and the overhead activity. They expected to see evidence of their anxious moods through delays in touching the images of the faces of the other primates, but not control images of simple grey squares. This pattern would suggest the macaques were more attuned to potential threats in their environment while the Air and Water Show was taking place.

This turned out to be the case. Importantly, they were not slower to use the computers because of the air show activities, because they did continue to touch other images (the plain gray squares) at similar speed—they only reacted less quickly to images with content meant to elicit emotion (other monkeys). However, the results for chimpanzees and gorillas were more ambiguous. Overall, they seemed to indicate that the apes were less anxious in response to the stimulation provided by the Air and Water Show.

In a nutshell, says Katie Cronin, Ph.D., director of the zoo’s Animal Welfare Science Program, “The apes didn’t show the same response slowing that the Japanese macaques did. We thought that might be because the macaques were newer to the zoo and had less previous exposure to the air and water show, but we can’t say for sure.”

While scientists do think they quantified changes in mood, it’s much harder to tell exactly why some primates’ moods changed—and why some did not. It could be that chimps and gorillas, who spend more of their time inside compared to the macaques, didn’t experience the noise as intensely. It could be that the macaques, who had only been at the zoo since 2014, hadn’t yet figured out that the noise didn’t pose a threat (the apes had experienced the annual increase in noise for 13 years by this time).

Or it could be that macaques are a bit more attuned to aerial predators than their larger cousins—after all, birds of prey are known to swoop down and capture them. There are many possible reasons for the mood changes, including the simple fact that each primate is an individual and each one will react differently to stimuli from the environment.

Lincoln Park Zoo continues to monitor the behavior of the Japanese macaques, western lowland gorillas, chimpanzees, and dozens of other species around the zoo with the ZooMonitor app. This app was created at Lincoln Park Zoo and allows caretakers to see changes in behavioral patterns and habitat use that allow us to tailor their care to ensure their comfort and wellbeing.

Offering Options

At Lincoln Park Zoo, one way Animal Care staff alleviate the type of stress that animals may experience from events is to make sure they have as many choices as possible. If they are able to escape loud noises or environmental stressors they don’t like and move into more comfortable spaces, individuals have a sense of control that can increase their wellbeing when new situations arise.

Regenstein Macaque Forest, where the Japanese macaques reside, includes complex rock features and natural topography where the animals can choose to be near guests at viewing windows, hide in long grasses or up in trees, or take shelter in rock caves, or hang out in their behind-the-scenes space. They have hot rocks , hidden fans, and a running stream to help them stay warm or cool down, and our ZooMonitor data has shown that the macaques use these options to keep comfortable.

Similarly, the gorillas and chimpanzees at Regenstein Center for African Apes can choose to be inside or outside, to participate in scientific research or not, to spend time near with humans that visit the habitat. Research from the Lester E. Fisher Center for the Study and Conservation of Great Apes showed that the apes were more comfortable when they had the option to move indoors or outside, regardless of whether they chose to use the spaces. Again, having choices seemed to improve their wellbeing.

In the future, Lincoln Park Zoo will continue to focus on making sure animals — and not just the primates — have options.

“The zoo’s new strategic plan focuses on choice and agency to support animal wellbeing,” Cronin said. “This will be a continued focus of the Animal Welfare Science Program and the Fisher Center. We will get creative with touchscreen computers, ZooMonitor, and other approaches to ask animals what they want and how they feel, so we can give them meaningful choices that provide them with control over their days.”

Bonus: This Facebook post shows another animal at the zoo, Jabari the lion, exercising his option to rest outside while watching one of the planes fly by during the 2022 Chicago Air and Water Show.


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