Always On Display: What Does Snake Stress Actually Look Like?

This study explored a question that has long been overlooked in animal welfare research: how does human presence affect captive snakes? The findings add to growing evidence that reptiles are far more behaviorally sensitive and have far more complex welfare needs than is often assumed.

The researchers observed three snakes housed at Adelaide Zoo in Australia, including a red-bellied black snake, an inland taipan, and a rough-scaled python. They experimentally manipulated how close people were allowed to get to the enclosures in order to measure changes in the snakes’ behavior and enclosure use.

The study consisted of three separate visitor conditions:

• Visitor-natural: Visitor viewing distance was kept as is  (135 centimeters from the enclosure).
• Visitor-control: Visitors were kept farther away from the enclosure (210 centimeters).
• Visitor-experimenter: A person was stationed very close to the enclosure (65 centimeters) and interacted conspicuously throughout the observation period (e.g., putting their hands on the glass, waving their arms, making other sudden movements). All other visitors were kept 210 centimeters away.

The researchers collected 144 hours of behavioral data. A total of 72 half-hour sessions were recorded for each snake, with 24 sessions for each of the three conditions.

During the high-interaction visitor-experimenter condition, snakes displayed significantly higher levels of abnormal behaviors. These included freezing, lunging at the enclosure glass, pushing, climbing, or digging at the enclosure walls, rapid, jerking body movements, and tail flicking — all behaviors the researchers identified as potential indicators of stress or compromised welfare.

Under normal visitor conditions, abnormal behaviors averaged only about 1% of observations. When visitors were kept farther away, abnormal behaviors averaged around 2%. Under the intrusive close-contact condition, abnormal behaviors jumped to 8.5% of observations. Statistically, this increase was highly significant, meaning the behavioral changes were unlikely to be random.

The researchers also found that snakes moved around their enclosures more during the intrusive human interaction condition. Traditionally, increased activity is interpreted as a sign of engagement in captive animals, demonstrating that they’re interested in exploring their surroundings. But this study challenges that assumption for reptiles. In fact, the authors suggest the opposite may be true.

Heightened movement in reptiles could actually reflect stress, vigilance, or agitation rather than positive stimulation. Although not quite statistically significant, active behavior increased from approximately 10% under normal visitor conditions to 18% during the intrusive visitor condition. This finding is important because welfare research in zoos has historically focused on mammals and birds, but reptiles have different behavioral baselines and sensory ecologies. Thus, a snake resting motionless in view may actually represent habituation, not poor welfare per se.

Normal visitor conditions appeared to produce the most stable welfare state overall. Snakes showed:

• The lowest levels of abnormal behaviors;
• Lower levels of activity; and
• Higher rates of inactivity while remaining visible in the enclosure.

The researchers suggest this may indicate that snakes can habituate to predictable, low-intensity human presence. In other words, regular zoo traffic may become part of the animals’ expected environment, while unpredictable, close-up behaviors, such as tapping the glass or arm waving, may be seen as threatening and therefore more stressful.

That being said, there are two important limitations worth noting: the rough-scaled python is a species mainly active at night that possesses heat-sensing pits (meaning they can detect heat from prey, predators, and their surroundings), while the red-bellied black snake and inland taipan are species primarily active during the day. These factors may have shaped their responses to the different experimental conditions (and the zoo environment in general). Additionally, the researchers confirmed that the snakes’ enclosures didn’t provide hides that could fully conceal them from view. This may have influenced the findings, as snakes may rely on secure, fully enclosed hiding spaces to feel safe and regulate stress.

Still, the study highlights how understudied reptiles remain in animal welfare science. Although reptiles make up approximately 11% of animals housed in zoological institutions worldwide, they accounted for only 3% of zoo welfare publications between 2008 and 2017. The authors argue this gap has serious consequences. Because reptile welfare research is limited, many husbandry standards continue to rely on anecdotal care practices and longstanding assumptions — or “folklore husbandry” — rather than empirical evidence.

Perhaps most importantly, the study calls for the development of species-specific welfare standards for reptiles rather than forcing snake behavior into mammal- or bird-centered frameworks. The authors emphasize that common welfare indicators used for other animals may not accurately reflect positive welfare in snakes. The study ultimately concludes that snakes aren’t passive, indifferent display animals. They respond behaviorally to human proximity and activity, and intrusive visitor interactions can negatively affect their welfare.