A new study suggests that a warming climate may be beneficial to rattlesnakes found in almost every part of the continental United States, but especially the pacific rattlesnake.
Pacific rattlesnake (Crotalus oreganus) populations across the southwest are thriving, according to a study published in Biology and Evolution last year by researchers at Cal Poly San Luis Obispo and the University of Michigan.
Sometimes referred to as the Northern Pacific rattlesnake, this venomous pit-viper is found in western North America from the Baja California Peninsula to the southern interior of British Columbia, where it is one of only three remaining rattlesnake species in Canada.
Rattlesnakes cannot control their body temperatures, being dependent on the environment for warmth. The research team found that the average body temperature of coastal rattlesnakes in the study was 70 degrees, and for inland rattlers, it was 74 degrees Fahrenheit.
However, the researchers found that when given a choice, the snakes actually prefer a body temperature of 86-89 degrees Fahrenheit – much warmer than what they generally experience in nature, which suggests they will do well in a warming world, reports The Guardian.
“The moral of the story is that as temperatures rise, it approaches the snakes’ optimal temperature,” says Hayley Crowell, lead author of the study. “That’s a favorable change for these snakes.”
The researchers didn’t start out to study climate change and its effects on rattlesnakes, and it is an interesting story. They wanted to know more about the physiology and thermal ecology of rattlesnakes: how they warm-up and cool down, comparing seven species of rattlesnakes living in coastal areas and central California.
To accomplish this, they implanted small temperature loggers – about the size and shape of a watch battery in the snakes so they could monitor their temperatures. And of course, as was noted earlier, they found most snakes recorded temperatures of 70 to 74 degrees Fahrenheit.
But here is what’s interesting. They also brought some snakes back to the laboratory and set them in a large box that had different temperature areas, letting the snakes pick where they wanted to coil up.
Given the choice, the snakes preferred their body temperature at a balmy 86 to 89F – much higher than their temperature in nature. “All the snakes were choosing higher temps,” says Crowell, “warmer than where they were living.”
Crowell added, “There are a lot of ecological pressures in nature that could prevent rattlesnakes from basking, such as the risk of increased exposure to predators. A warmer climate may help these snakes heat up to temperatures that are more optimal for digestion or reproduction.”
There are a few other advantages to living in a warmer climate – if you are a rattlesnake. One obvious reason is a longer active season, giving them more time to hunt and feed. In addition to seasonal changes, rattlers could spend more active hours during a given day.
Snakes digest very slowly and need to eat only about 500 to 600 calories a year – the equivalent of a single ground squirrel. (Humans, on the other hand, need more than 1,300 times more calories to survive.)
In the real world, a rattler needs additional calories to hunt and bear young among other activities, however, the calculations point to the snakes’ ability to survive even if prey isn’t plentiful.
“Rattlesnakes require very little energy to exist,” said Crowell, who earned a master’s degree in biological sciences at Cal Poly.
“We are so used to climate change studies that forecast negative impacts on wildlife — it was interesting to see such starkly different findings for these snakes,” said Crowell, who is seeking a doctorate at the University of Michigan.
