Stressed rattlesnakes found to calm down in the company of a nearby ‘friend’

Newswise — When animals experience acute or persistent stress, they generate additional hormones that induce changes in the nervous system, immune reaction, and conduct. Certain animals, when exposed to a member of the same species, can adjust their reaction to mitigate stress. This phenomenon is referred to as social buffering.

There is evidence indicating that snakes can display intricate social behavior. However, the extent of social buffering in reptiles, as well as in other non-social organisms and solitary foragers, remains relatively unexplored. Presently, a group of researchers in the United States has investigated whether rattlesnakes residing in Southern California employ social buffering as a means to alleviate acute stress.

"In our study published in Frontiers in Ethology, we demonstrated that when two snakes were in each other's presence during a stressful situation, they exhibited the ability to mitigate each other's stress response, similar to how humans can support one another during challenging events," stated Chelsea Martin, a PhD student at Loma Linda University and the lead author of the research. "This reduction in the stress response has not been previously observed in any reptile species."

Snakes that rattle buffer

When subjected to stress, the presence of a fellow snake companion significantly decreased the magnitude of heart rate change in the snakes. Since the researchers conducted their study using wild-caught rattlesnakes, they were able to demonstrate that social buffering likely occurs naturally and can endure even in captive settings.

"Our test snakes were sourced from populations that exhibit both individual and communal overwintering. Interestingly, we did not observe any disparities in social buffering between snake populations that experienced either individual or group overwintering," Martin explained. "Furthermore, we did not observe any variations in social buffering based on the sexes of the snakes."

The hibernation behavior of montane rattlesnakes, characterized by communal hibernation, potentially signifies stronger social networks compared to lowland rattlesnakes that typically overwinter individually. Additionally, it is understood that female rattlesnakes gather during pregnancy and stay with their newborn offspring. By considering these factors, the researchers were able to determine that the tendency to exhibit social buffering was equally prominent in both snake populations and among female and male snakes.

Snakes in a bucket

In their study, the researchers evaluated social buffering in 25 wild-caught southern Pacific rattlesnakes through three different scenarios. Firstly, they observed the snakes when they were alone. Secondly, they introduced an inanimate control object in the form of a rope. Lastly, they examined the snakes in the presence of a companion of the same sex.

To gauge the levels of acute stress and social buffering, the researchers utilized the measurement of heart rates in rattlesnakes. In order to collect the necessary data, the snakes were equipped with electrodes near their hearts, and these sensors were connected to a heart rate monitor. The snakes were subsequently placed within a bucket, creating a dark and enclosed testing environment.

Following a 20-minute adjustment period, the snakes were intentionally disturbed by the researchers. Chelsea Martin and her colleagues measured several parameters, including the increase in the snakes' heart rate from the baseline, the duration it took for their heart rate to return to normal, and the length of time they spent rattling. These measurements provided insights into the snakes' physiological stress response and their behavioral reactions.

An image boost for rattlesnakes

"Our findings shed light on the social behavior patterns exhibited by snakes," Martin commented. "Moreover, it has the potential to positively influence the perception of rattlesnakes. They are frequently portrayed negatively in public opinion, but our research could contribute to changing that perspective," she further explained.

The scientists also acknowledged certain limitations of their study. One of the constraints was that the snake pairs were confined to very limited spaces throughout the duration of the experiment. Therefore, they did not investigate whether a stress-buffering response occurs when snakes are in close proximity but not in direct physical contact. Additionally, the impact of familiarity between two snakes on their social buffering response remains an unknown variable that the researchers hope to explore in future studies.