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Snakes: They’re just like us – at least in one way.
Like humans, the slippery reptiles can rely on peers to stay calm during times of stress, according to a new study published Thursday in the journal Frontiers in Ethology.
The study authors focused their research on South Pacific rattlesnakes, or Crotalus helleri, which are common in Southern California. They found that the snakes that went through stressful situations in the presence of a companion showed lower heart rates compared to those that went through the stress alone.
These findings marked the first time that social buffering — a phenomenon in which having companions nearby can reduce biological responses to stress — has been recorded in reptiles, according to lead study author Chelsea Martin, a doctoral student at Loma Linda University in California. It has previously been observed in humans, rodents, birds and non-human primates.
“Snakes and reptiles are really interesting because I think they are often overlooked in their behavior,” Martin said. “People are often very afraid of snakes… (but) they are not so different from us. They have mothers who take care of their children. They can reduce their stress when they are together. That is something that we as humans also do.”
How to study snake stress
Martin teamed up with Dr. William Hayes, a professor of Earth and Biological Sciences at Loma Linda, to set up the study.
It was Hayes’ idea to investigate the stress response of snakes, Martin said.
The research team removes rattlesnakes for people who don’t want them near their homes, she said, so Hayes spends a lot of time driving around with buckets of reptiles in his car.
“He had noticed that when he had two hoses together in a bucket as he rode down the mountain, they seemed to rattle less or not at all — unlike when he only had one hose in the bucket,” she said. Rattlesnakes tend to shake their tails and emit their distinctive warning sound when threatened.
Another colleague suggested that this behavior could be a sign that the snakes were engaged in social buffering, and their team designed an experiment for the rattlesnakes.
They used 25 South Pacific rattlesnakes that had been caught in the wild, including some that came from lowland areas and others from the mountains. (Lowland Pacific rattlesnakes are known to hibernate together or spend the cold months in each other’s company, while mountain snakes do not.)
The researchers placed the snakes in 19-gallon plastic buckets, then sealed them and piped the containers to simulate a stressful environment. They used an over-the-counter heart rate monitor to monitor the animals’ stress levels as they tested the subjects three ways: alone, with a companion, and with a rope roughly the same size as a fellow snake (to ensure the presence of another snake, and not just another object, caused the reduced stress response).
They found that the snakes’ heart rates were significantly lower when placed in the bucket with a companion compared to being alone or with the rope. And that result was true for lowland and mountain snakes as well as for males and females.
What’s next for snake research
These findings, according to the study authors, could have broad implications not only for Pacific rattlesnakes, but for reptiles in general.
Martin and Hayes said similar social buffering behaviors could occur in numerous snake species, as well as lizards, crocodiles and other scaly creatures.
“No one has really looked at[social buffering]in reptiles,” Hayes added.
Dr. Erika Nowak, a herpetologist and assistant research professor at Northern Arizona University’s Center for Adaptable Western Landscapes, agreed that research on snake social behavior has been limited until recently. She was not involved in the new study.
“I’m so happy to see a well-thought-out study that adds to our understanding of sociality in rattlesnakes,” Nowak said via email. “Their sociality is ‘cryptic’ only because we scientists have not assumed that they (are) fully social animals, and so we have not always carefully searched for behaviors that support sociality.”
This evidence of snakes engaging in social buffering is consistent with other social behaviors she observed in her own study, Nowak added.
“I observed two wild male western diamondback rattlesnakes hibernating close to each other, traveling together during the active season and even defending each other against me,” she said.
This study could provide a starting point for additional research on snake sociality. Nowak said she’d like to see studies on how social buffering might affect snakes’ levels of cortisol, also known as the stress hormone. And studies like this one can provide information about how snake handlers treat the animals in captivity.
“(T)his (and other) research clearly shows that snakes can benefit from cage mates,” Nowak said.
Researchers also said they hope this study will have a positive impact on public perceptions of snakes. They know that most people are not wild about the reptiles – especially the venomous variety.
“Please don’t hype these animals off as dangerous animals. They are clear. But they’re just trying to protect themselves,” Hayes said. ‘They’re afraid of us. They are withdrawn animals. … So we would really appreciate a more positive emphasis on snakes.”
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