What Do Frogs and Toads Do During the Winter in Colorado?
Certain species, such as black bears and small rodents, survive Colorado's cold winters by hibernating through the entire season. Other kinds of wildlife, like deer and elk, aren't phased at all by the freezing temperatures or snow on the ground. And for some animals, that aren't seen often as it is, what they do during the wintertime is even more of a mystery.
For instance, how do frogs and toads get through the winter in Colorado?
Being amphibians, these creatures are cold-blooded, so their body temperatures take on the temperature of the environment around them. But different types of frogs and toads have varying ways of coping with winter and the weather that comes with it.
Boreal toads living in the Centennial State find somewhere warm to hole up in when winter rolls around. Usually, this is in a small mammal's burrow, in a rock chamber near a stream, or in an insulated beaver dam. According to the National Park Service, boreal toads spend more than half of their lives hibernating.
Similar to boreal toads, Colorado's wood frogs overwinter in burrows. However, their holes are dug into the soil. Because the temperature drops below freezing underground, the water in the wood frog's body freezes. As a result, their hearts actually stop beating, ice forms in the coelomic cavity and beneath the skin, and blood stops flowing. While in the burrow they don't die, but essentially freeze themselves until it's warm enough to come back out again. When wood frogs thaw in the spring, their hearts spontaneously start and blood begins to flow. The frog recovers coordination and can resume normal activities within 48 hours.
Leopard frogs that live in Colorado's ponds and lakes spend the winters waiting it out at the bottom of the water source. Once at the bottom of a pond, they settle themselves into the mud. According to Boulder County Open Spaces, Northern leopard frogs can respire through their skin but can't survive freezing solid like some of the other species can. Rather, their metabolic rates slow as temperatures drop, so they don't need to come to the surface to breathe. During the winter, these frogs will absorb oxygen from the water through their skin.
Since bullfrogs are not native to Colorado, it likely explains why the ones that live here have to hibernate during the winter. Bullfrogs park themselves in the mud at the bottom of a pond, carving out tiny underground lairs where they can rest until the temperatures warm back up. Sometimes, bullfrog tadpoles will remain active all winter long, delaying undergoing the metamorphosis process until the closing of the next summer.