When facing stress, either chronic or acute, animals produce more hormones, which then cause changes in their nervous systems, immune responses, and behavior. In some cases, animals can regulate their stress response when they are in the presence of another individual of the same species. This phenomenon is called social buffering.
Although some studies suggest that snakes have complex social behaviors, exploration of social buffering in reptiles, as well as in other organisms that are not naturally social or are solitary foragers, remains limited. To address this gap, a team of researchers in the US looked at whether rattlesnakes use social buffering to alleviate stress levels.
“When two snakes were together and experienced a stressful situation, they could buffer each other’s stress response, much like what happens to humans when they endure a stressful event together,” Chelsea Martin, study author, said in a media statement. “This response hasn’t been reported previously in any reptile species.”
Coping with stress is better in pairs
In their study, the researchers looked at the behavior of 25 southern Pacific rattlesnakes captured from the wild. The aim was to evaluate the presence of social buffering under three different scenarios: when they were alone, in the presence of a non-living object (a rope used as an inanimate control), and when they had a same-sex companion.
The southern Pacific rattlesnake (Crotalus oreganus) inhabits regions spanning southern California and Mexico's Baja California. It has a distinctive feature at the end of its tail: a rattle composed of keratin. When threatened and stressed, the snakes produce a hissing sound by vibrating their rattles, which serves as a deterrent to potential predators.
The researchers utilized heart rate measurements as an indicator of acute stress and the effects of social buffering. Electrodes were attached near the snakes' hearts, and the sensors were connected to a heart rate monitor. The snakes were then placed inside a bucket, which served as a dark and enclosed testing environment.
After allowing the snakes to acclimate for 20 minutes, they were deliberately disturbed. The researchers recorded the increase in the snakes' heart rates from baseline rates, the time it took for their heart rates to return to normal, and the duration of time they spent rattling. They found that heart rate did not go up as dramatically when the snakes had a friend nearby.
This suggests that social buffering occurs in rattlesnakes and is likely a natural phenomenon that happens in captive settings. “Our test snakes came from populations that overwinter individually and communally. We found no differences in snake populations who did or didn’t overwinter in groups. We also didn’t observe a difference between sexes,” Martin said.
The study not only provides new insight into the social behavior of rattlesnakes but also helps improve their image, the researchers said. However, they pointed out some limitations. Snakes were kept in confined spaces during the experiment, which means the researchers didn’t examine whether stress buffering happens when snakes are close but not in physical contact.
The study was published in the journal Frontiers in Ethology.