Stressed snakes are aggressive snakes

New research shows a snake’s propensity to strike is best predicted by its baselines stress levels, not a recent stressful experience.

“Most people think a snake is more likely to strike after you have handled or harassed it,” Tracy Langkilde, professor and department head of biology at Pennsylvania State University, said in a news release. “Our results show this is not true. We show that how stressed a snake gets when handled or harassed does not determine how likely it is to strike.”

During a stress test, only eleven of the thirty-two cottonmouth specimens struck after being handled with tongs for the first time. When snakes were confined for seven minutes before being handled, only seven struck.

The snakes that struck were more likely to have elevated baseline levels of corticosterone, a hormone that rises in response to heightened stress levels.

The stress experiment was conducted in the wild, not in a lab. Researchers sought out encounters with cottonmouths in the beaver marshes and cypress swamps of Alabama. Researchers took blood samples to measure corticosterone levels before and after subjecting the wild snakes to stressful confinement.

Their analysis showed corticosterone levels rose in response to being confined, but the rise failed to predict the likelihood of a strike after being released and handled again.

“These are some of the first results we know of that connect stress biology with anti-predator behavior in the wild,” said undergraduate researcher Mark Herr.

The research was published in the journal General and Comparative Endocrinology.