Rattlesnake personalities may influence venom expenditure during defensive bites

A study has found that rattlesnakes exhibit repeatability in the amount of venom a particular snake expends while defending itself. The new data contributes to the evidence that snakes have personality traits in defensive contexts given the consistent individual tendencies.

The study, conducted by researchers at Loma Linda University, led researchers to conclude that not all snakes are the same and that some snakes in the wild may be less dangerous for hikers than others.

Researchers gave 48 captive snakes an opportunity to bite three times over a four week period and found that most were consistent in their response. Some chose to bite all three times, some only twice, and some not at all. While prior studies have examined this type of defensive behavior, this study went further by measuring venom quantities expended during the bites. Some individuals consistently delivered a lot of venom in their bites, and some consistently gave much less, thereby displaying consistent tendencies.

"This study gives us a better understanding that reptiles, such as rattlesnakes, are behaviorally complex and have personalities like humans do," said Chelsea Martin, PhD, the lead author of the study.

Researchers published their article in Frontiers in Ethology on October 8.

Martin advised hikers to be respectful of rattlesnakes and leave them alone. She said most snakes don't want to interact with humans and prefer to blend in with their environment and not be seen because they are prey for raptors and large carnivorous mammals.

The findings were based on routine venom extractions in which the snake could voluntarily withhold or inject venom into a membrane-covered beaker. The team plans to conduct further studies to assess whether the repeatability they observed is influenced by the habitat that the snakes come from and if it occurs in additional contexts, such as exploring new environments or predatory bites, which would be required to conclude that the behavior is shaped by personality.