Where do Idaho’s rattlesnakes go in the winter, anyway?
Published at
Vincent Medina, Idaho Statesman
BOISE (Idaho Statesman) — What happens to Idaho snakes during the winter?
The Idaho Fish and Game office in Nampa spoke with the Idaho Statesman over the phone to tell us about what is known as the “brumation process.”
What happens to snakes during brumation?
Jamie Utz, a wildlife diversity biologist at the Nampa regional office of Idaho Fish and Game, described brumation as hibernation for reptiles and other amphibians.
“People who are familiar with hibernation know that classic example of a bear that goes to sleep for the winter time; reptiles are a bit different,” Utz said. “They will occasionally wake up throughout the winter, especially if it’s warm and sunny. They might grab something to eat, they will get something to drink and then they’ll go back into their kind of suspended state.”
The biologist explained snakes are more likely to find something to drink rather than hunt for food during brumation to avoid exerting too much energy.
According to the Idaho government website, the two types of rattlesnakes in the Gem State are prairie rattlesnakes in Central Idaho, and western rattlesnakes in the south and western portions of Idaho.
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Where do snakes spend brumation?
Utz explained that snakes, particularly rattlesnakes and garter snakes, will usually search for places underground during the winter to stay warm with a group of snakes called a den.
“Reptiles and amphibians are exothermic, which means their body temperature is reflective of the environmental temperature,” Utz said. “So those species in particular tend to form a hibernaculum, and they pile into one spot that will have a fairly steady temperature throughout the winter. Oftentimes it’s a lava tube, or if you’re unlucky you might have a basement or a subterranean structure that holds a steady temperature.”
Utz emphasized that instances of people finding a den of snakes in their basements are very rare and likely not to happen in more populated areas. She referred to a situation in 2011 where a couple in Rexburg bought a five-bedroom home and found the basement infested with snakes.
“(The snakes) are going to be in a more natural setting so there might be some rock crevices, a collapsed lava tube or even some caves,” Utz said. “Caves typically hold at about 55 degrees year-round, so spaces like that are what they’re looking for.”
Are the den spaces marked to avoid during the winter?
The biologist said it would be rare for a person to find a den of snakes during brumation. While regional agencies like the Bureau of Land Management know which areas in the state tend to attract dens during the winter, they have chosen to keep that information from the public.
“Not everyone, unfortunately, has respect for wildlife and we’ve had cases of people going into these spaces and killing snakes at random, and that’s not what we want to see,” Utz said. “Reptiles that are in a state of brumation are going to be very slow to move, they’re not going to have a lot of energy to evade or jump out and bite. If you were to find brumating snakes, it’s not going to be a direct threat to you, but it’s certainly something that we would want people to be respectful of.”