This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Imagine encountering a rattlesnake in your backyard or while on a hike. It will most likely "freeze" to avoid attracting attention, but if it feels especially threatened, it may rattle and even strike, delivering a painful dose of venom.
When a rattlesnake bites in self-defense, how much venom does it inject? The answer depends partly on the snake's size. Contrary to popular myth, the larger snakes deliver much more venom.
However, our new study suggests another important factor: the individual snake's personality. In a study published in Frontiers in Ethology, we found that southern Pacific rattlesnakes (Crotalus oreganus helleri) exhibit consistent individual differences in defensive behaviors, including how much venom they expend when biting. The findings suggest that venom deployment has a repeatable component that may reflect differences in temperament.
The study offers new insight into how animals use chemical weapons and raises intriguing questions about the potential consequences of individual snake temperament during interactions with humans. Venom can be an expensive biological resource. Snakes must produce it, store it and replenish their supplies after use.
Although venom can help a rattlesnake defend itself against a potential predator, expending too much could leave less available for capturing prey or defending itself later. Conversely, deploying too little venom might fail to deter a threat. Our prior work has shown that rattlesnakes can regulate their venom delivery, but do individual snakes consistently differ in how they use this resource?
To answer this question, we studied 48 southern Pacific rattlesnakes, including 35 adults and 13 subadults. We subjected each snake to three standardized venom-extraction trials separated by two weeks. During the trials, we videotaped and recorded several defensive behaviors, including the number of strikes while restraining the snake in a tube, whether it bit the membrane-covered beaker during the venom extraction, the number of venom pulses delivered through its fangs and the volume of venom expelled.
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