Rattlesnakes Calm Down When Near a Friend

Just like seeing a friend after a stressful work week can make everything seem OK, rattlesnakes have been found to feel calmer when they have a buddy nearby.

This is one of the first times that reptiles exhibiting "social buffering," a reduction of stress in the presence of another of their species, has been studied, according to a study published on July 6 in the journal Frontiers in Ethology.

The researchers found that when exposed to a stressful situation, the rattlesnakes experience an increased heart rate—among other symptoms of anxiety—but these increases were much lower if there was another snake companion nearby.

"We showed that 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, a researcher at California's Loma Linda University and co-author of the paper, said in a statement. "This dampening of the stress response has not been reported previously in any reptile species."

The researchers tested 25 southern Pacific rattlesnakes caught from the wild and assessed the impact of stress when the snakes were alone, both with a same-sex companion and with a control object. They measured the snake's stress via their heart rate, recorded using electrodes on the body.

The snakes were placed in a dark bucket, and after 20 minutes were disturbed by a stressor. After this the researchers measured the change in heart rate and how long it took to return to baseline, as well as the amount of time the snakes spent rattling.

Rattlesnakes, specifically the southern Pacific rattlesnake, are venomous pit vipers found across southern California and Mexico's Baja California, and tend to measure between 24 and 55 inches long. These snakes have a characteristic rattle at the end of their tails made of keratin, which makes a hissing noise when they vibrate in threatening situations, designed to ward off predators. The rattle is therefore also a sign of stress in these snakes.

Researchers found that the snakes, when they had a friend nearby, had a much lower increase in heart rate, and their raised pulse returned to normal faster than those alone or with the control object.

"Our results provide insights into social behavior patterns of snakes," said Martin. "But it might also improve rattlesnakes' image. In the public eye they are often maligned. Our findings could help to change that."

These findings indicate that snakes have a more complex social life than we first thought, having only recently discovered that rattlesnakes will preferentially choose the company of their siblings over strangers. The fact that these snakes were wild-caught rather than captive since birth also shows that this is likely to be a natural reaction shown by the snakes in the wild.

The researchers also found that these stress reactions were the same regardless of if the snake's original population hibernated in groups, or alone. They were also the same between male and female snakes, the latter of which aggregate with newborn offspring.

"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," Martin explained. "We also did not observe a difference in social buffering between the sexes."

The scientists note that they didn't test for how the social buffering effect differed based on if the snakes were physically touching or just sharing a space, and if the snakes had previously met before or not. These unknown variables are hoped to be tested in further experiments.

Do you have a science story to share with Newsweek? Do you have a question about rattlesnakes? Let us know via science@newsweek.com.