How Climate Change Affects Winter Wildlife
By Christine Peterson, contributing writer
As temperatures drop and snow piles, our instinct is often to hunker down, stay warm and wait it out. While some wildlife species leave the state, migrating to Mexico or even South America, others remain, adapting to dropping temperatures in ways that have evolved for thousands of years.
But climate change, with shorter winters, thinner snowpack and more extreme outlying temperatures, could be threatening those carefully honed systems.
Here is a breakdown of some of Idaho’s most interesting winter wildlife adaptations, and ways climate change might be a concern.
White Animals in a Brown World
When people think of species that change colors to match their surroundings, chameleons are likely the first to come to mind. But for animals found in Idaho, little beats the snowshoe hare and ermine for clever camouflage. Each year, they switch from brown to white and back again to match the landscape. The adaptation has kept them alive and allowed them to escape predators—or better sneak up on their prey—for millennia. But the color change is triggered by the sun, not the weather, which means as winters shorten, their coats aren’t catching up, said Leona Svancara, a spatial ecologist and climate change liaison with the Idaho Department of Fish and Game. “They become little light-colored beacons in this brown world.”
Waking up Too Early
Hibernation is the classic adaptation for animals in a cold climate. And what could be better than crawling in a cozy den and sleeping through the harshest parts of the year? While it’s worked perfectly for everything from the smallest of bats to the biggest of bears, researchers are beginning to worry about what happens in a shifting climate that has shorter winters but more relative extreme outliers of cold. “If it gets warm enough,” Svancara said, “they can come out of hibernation and we go through an extremely cold period that physiologically they are not prepared for.”
Adapted to the Cold—Not the Heat
Watching a Canada lynx walking across snow is like watching an eagle fly. They grace the surface of feet-deep snow with their enormous, furry paws and light bones, and rarely sink in. It’s what makes them efficient winter predators, tracking down animals like snowshoe hares. But these adaptations to winter—the thick coats, big paws and fragile bones—aren’t likely as well adapted to warming temperatures. It’s also critical to their survival that their scattered populations across the northern U.S. and Canada are able to connect. As the climate warms, and species that require deep snow and cold winters retreat to higher elevations and further north, they could become more disconnected to other populations.
Unlike similarly-sized rodents, pikas, which are more closely related to rabbits, don’t hibernate through winter. They spend most of the summer gathering grass and stay in their nests all winter eating their carefully stored forage, said Kevin McKelvey, a research ecologist with the U.S. Forest Service. Deep snow keeps their dens at a comfortable 34 or so degrees, never cold enough to freeze. Climate change is causing two problems: drier summers mean less grass available for forage and thinner snowpack means more exposure to the cold. “They use the snow to stay warm,” he said. “And when they’re exposed to too much cold, they eat too much grass and don’t make it.”
It isn’t all hopeless though. Work can be done on the ground to maintain connected habitats, allowing these animals to move more freely into retreating winter conditions, said Jeffrey Hicke, an associate professor at the University of Idaho.