You are in a desert and dying of thirst. All of a sudden, storm clouds appear overhead, and the sky starts to spit tiny drops of liquid. How would you quickly make the most of the potentially lifesaving precipitation?
One more thing, you don’t have any hands.
Prairie rattlesnakes have evolved an easy solution to this problem. They simply coil up and turn themselves into rain-collecting pancakes.
“It is a behavior that is seen in several different species of snakes,” said Scott Boback, a herpetologist and ecologist at Dickinson College in Pennsylvania. But “most of that information has been very anecdotal.”
After all, rattlesnakes don’t like being found. And precipitation in arid environments is infrequent. If Dr. Boback and his colleagues wanted to study the rain-harvesting phenomenon, they realized they’d have to make it rain.
With garden sprinklers and video cameras at a well-known rattlesnake hibernaculum just outside Steamboat Springs, Colo., Dr. Boback and his team recorded nearly 100 snakes reacting to simulated rainfall. That allowed them to quantify the behavior and break it into stages.
Not only did they observe snakes drinking off their own flattened bodies, as well as the ground, but they also saw snakes lean over and take sips off their neighbors. They also found that snakes in large aggregations were more likely to drink off other snakes than those in small clusters were.
“Some of the aggregations are literally massive,” said Dr. Boback, an author of a study describing the behavior in the journal Current Zoology published at the end of 2024. “So many snakes, all coiling together, that it essentially creates a carpet of snakes.”
All of this suggests that warmth and protection may not be the only benefits for rattlesnakes that den together.
Interestingly, the scientists also watched as some rattlesnakes shifted their coiled bodies out over ledges, like a cantilever, to create a horizontal rain-collecting platform across uneven ground. The snakes also sometimes tipped their entire coiled bodies forward, coaxing the water toward their mouths, as we might with a bowl to consume that last slurp of tomato soup.
Most mysteriously of all, about 12 of the snakes appeared to drink water that was landing on their heads and that was being channeled to their mouths through some unknown mechanism. “We don’t know what’s going on there,” Dr. Boback said.
None of this would be possible without a curious and microscopic arrangement on the rattlesnakes’ scales. The scales are hydrophobic enough to make water droplets bead up — but hydrophilic enough to keep them from rolling right off the reptiles.
“There are equivalent examples in plants,” said Konrad Rykaczewski, a mechanical engineer at Arizona State University who was not involved in the study. “Go look at rose petals after it rains. You’ll see large droplets sticking to it.”
In a 2019 study, Dr. Rykaczewski showed that desert rattlesnakes possessed this rain-catching ability, while king snakes, which live in the same areas but have smoother scales, do not.
Dr. Rykaczewski called the new research “very cool,” but he wasn’t as sure about whether the snakes’ heads have water-guiding channels, similar to what have been shown on Texas horned lizards. He’s also in no hurry to find out.
“I mean, a dead rattlesnake can bite you still, right?” he laughed.
Gordon Schuett, an evolutionary ecologist at Georgia State University and a co-author of the study with Dr. Rykaczewski, said that he had seen rain-harvesting behavior many times in the field. But the considerable sample size and detail of the new study are what “makes it outstanding.”
In the end, Dr. Boback is hopeful that the image of rattlesnakes peacefully sipping water off each other could remind more people that these animals are social beings, with intimate behaviors and more complexity than we’ve traditionally given them credit for.
“We’ve got this video of the snakes drinking off of each other’s heads, and it’s like the cutest thing in the world,” Dr. Boback said. “They’re practically kissing each other.”
