Surprising Science: Welfare for Reptiles

December 21, 2023

When it comes to the wellbeing of animals, big and charismatic mammals tend to get all the attention. Humans feel a natural affinity for animals we find “cute,” or sympathetic, or intelligent—like elephants, dolphins, lions, or rhinos. And because humans are also mammals, it may be easier for us to feel that we understand the inner lives of the animals more closely related to us.

Some research indicates that even scientists gravitate toward bigger, rarer, more elusive animals when it comes to which species to study. Yet these animals aren’t always necessarily the ones that need the most help. And they aren’t the ones that make up the largest part of zoo and aquarium populations.

Lincoln Park Zoo recognizes that all creatures that live here, including fish, herptiles (reptiles and amphibians), birds, and invertebrates, deserve to have as high a quality of life as possible. Thus, Animal Welfare Science Program scientists and interns are among the pioneers working to improve the welfare of animals that aren’t mammals in zoo environments.

Tiny, Blanding’s turtle, courtesy of Alex Thomson

Recently, this includes multiple studies that are trying to determine the types of habitat features that reptiles prefer, which can contribute to their wellbeing.

“Research on reptiles and amphibians does not happen as much as one would expect, considering how common they are in zoos,” explains Natasha Wierzal, ZooMonitor Research Assistant in the AWSP. “And the research available from laboratories tends to be about how they do in barren housing versus ones that have been enriched. One of the goals behind our study was to continue caring for animals in enriched environments and start to tease out   what aspects of the enriched habitat they prefer. A lot of what we know is almost folklore—information that is passed down. We know they need hides—but why is that the case? What works best for each species and individual?”

The Challenges of Studying Reptiles

One of the issues with studying reptiles is that the ways in which they perceive the world is so different to humans. As cold-blooded animals, reptiles have lower metabolic rates and consume fewer calories. This also means they move less—an adaptation that allows them to live in harsh environments, like deserts, where endothermic animals (who are able to generate their own heat) would have trouble finding enough food and water to sustain them.

“Generally speaking, mammals or birds tend to  behave in ways that are more familiar to us as humans. At the basic level, reptiles don’t look like they’re doing much,” Animal Welfare Scientist Shannon O’Brien, Ph.D., says.

When cold-blooded animals behave in unexpected ways, they may be reacting to chemicals in the air, different temperature zones, or other things people can’t quite detect. Humans are simply not very good at reading their body language. And, as Wierzal points out, “We’re not even good at understanding other humans much of the time.” So how do researchers go about understanding reptile preferences?

Vera, box turtle, courtesy of Brittany Childs

There is enough research about certain reptile behaviors for scientists to extrapolate. For example, lizards and snakes use their tongues to sense smells in the air, so when scientists observe tongue-flicking, that often means the reptiles are exploring—an activity that’s generally considered a positive for welfare. Also, if an animal spends more time in one area, researchers can at least assume they like that spot enough to not avoid it.

It’s also helpful, given the challenges, to study reptiles for a longer period of time—because we aren’t necessarily recognizing their behaviors. Researchers can get a more complete picture of behavior patterns and habitat use by monitoring them 24 hours a day through wireless cameras. Additionally, the zoo dispatches interns and volunteers to observe and record the animals in person with the ZooMonitor app.

Selecting Substrates

Having an environment with complex elements is important for reptiles, but animal care staff want more information about which habitat features the animals prefer. This helps them offer the animals opportunities to seek these preferences, giving them more agency in their daily lives.

To find out more about what lizards, turtles, and snakes like, Lincoln Park Zoo researchers undertook two different studies. The first focused on substrates—the type of material used on the bottom of an animal habitat, which can provide shelter, humidity, bedding options, and more.

Using the video cameras, staff and interns constantly monitored a Blanding’s turtle, wood turtles, and spotted turtles in one habitat for five months straight. Animal care staff provided different substrates, including sand, bark chips, mulch, and sphagnum moss, for 14 days at a time. Then, data was collected on how the animals used each substrate with a direct heat source and without.

Gingko, wood turtle, courtesy of Alex Thomson

They found that the Blanding’s turtle preferred mulch, while the two wood turtles liked moss. The spotted turtles avoided land in general and stayed in the water, sometimes climbing onto logs to rest. That doesn’t, of course, mean that all members of the species have the same preferences, given how small the sample size was. It only reflects the needs of the animals in the study.

“The important part is that we take the information and incorporate it into the care,” O’Brien says. “I share this information with animal care staff so that we can determine how to provide these different substrates simultaneously, or rotate them out, to accommodate the needs of individual animals.”

Heeding Hide Preferences

The word “hides” refers to elements in a reptile habitat that allow an animal to take shelter or seek privacy inside them. Hides cater to a reptile’s natural inclination to conceal themselves in logs, rocks, and other natural elements. They are an important part of reptile care and should be offered regularly; experts believe that reptiles benefit from hides that they can touch in multiple places at the same time. Natural behavior would also suggest they should be be opaque and dark inside so the animal feels hidden.

The hides study at Lincoln Park Zoo looked at eight animals of four species: the African rock python, Gaboon viper, four Rio Fuerte beaded lizards, and two Aruba Island rattlesnakes. Researchers provided them with appropriate-sized dry and wet (watered daily) hides made of PVC pipe. They collected data daily for four weeks and switched locations of wet and dry hides after two. As with the turtle study, cameras recorded activity 24 hours a day during that month.

Gaboon viper

Scientists discovered some interesting trends. For example, the Rio Fuerte beaded lizards spent more time in the hide when it was on the ground. The African rock python liked it to be high. The animals preferred the hides during times when they are naturally inactive and all of them liked it drier.

“The African rock python never left his hide, but the rattlesnakes and the Gaboon viper used it infrequently,” Wierzal says. “Part of this makes sense because they have cryptic coloring so they can hide in plain sight, but this wasn’t the result other similar studies got, so perhaps the hide was not the preferred size or shape.”

Of course, these results bring up questions for further research . For example, researchers weren’t sure what impact the size of the crowd in Regenstein Small Mammal Reptile House had on the results. And as with the previous study, sample sizes are small and based on individuals. Only one type of hide was used, and perhaps other types or textures — or numbers of them, in habitats with several animals — would make a difference in usage.

Remarkable Reptiles  

But one thing the results did indicate is something zoo staff knew already: meaningful choices are important for animals. This was one of the first studies to ask reptiles what they prefer, and future studies will continue to reveal what choices are valued by the animals. More preference testing can also provide framework for other understudied animals, including invertebrates and fish. This work also helps people see that reptiles are individuals with preferences and abilities. 

“For a long time, reptiles’ ability to learn was underestimated,” explains Wierzal. “That has been changing, and animal care staff have been using positive reinforcement training to engage reptiles in voluntarily participating in their own care. We are all more interested in discovering what is possible with reptiles.”  

Next time you visit the zoo, don’t skip over the reptiles just because you don’t see them moving. Take the opportunity to observe, learn from, and enjoy watching these animals. And if you aren’t able to come to the zoo, visit to check out one species—the Jamaican iguana—online.

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