Spring Ahead! 5 Animals Who Hibernate - and Wake Up - Early

Even though there’s still snow on the ground, it is officially March -- and that means Spring is (almost) here! Spring is our favorite time of year here at na2ure because it’s a season of new life for plants and animals. We know animals will be crawling out of their comfy winter nests into the waking world soon… and when that happens, we know this winter will finally be over. Here are our 5 favorite early risers in the animal kingdom:


Arctic Ground Squirrel

Arctic ground squirrels are the largest squirrels in North America. They're unique in two other ways, too: 1) They're 1 of only 3 species of arctic animals that hibernate (the other two are close cousins the marmot, and the little brown bat), and 2) Their body temperature drops to 27 degrees Fahrenheit when they hibernate -- the lowest recorded body temperature for a hibernating animal. Scientists aren't quite sure why their body temperatures drop so low, but they do know that ground squirrels wake up every few weeks to warm themselves. Ground squirrels begin hibernation in early August and sleep until early April, when adult male ground squirrels dig their way out of the snow and stay close to the burrow to protect the females and young.



We've written about groundhog hibernation before, but we’ve just learned something new: climate change is altering their hibernation patterns. Groundhogs normally hibernate from October to March, but due to warmer global temperatures in the past 7 years they’ve been waking earlier and earlier. The whole reason some mammals hibernate is to conserve energy when food is scarce. Because most marmots use air temperature to determine when Spring -- and food -- is here, and because air temperatures have been warmer overall in the past few years, groundhogs have been waking up up to a whole month early. When that happens, they’re waking up when they have less energy and food is still scarce. And remember: groundhogs binge eat the veggie equivalent of a 15-pound steak to prep for hibernation. They need lots of food.


Chipmunks are the smallest member of the squirrel family. Essentially tiny tree squirrels that live underground, chipmunks don’t sleep all the way through winter. They don’t store fat and therefore can’t sleep through the whole season so they sleep in spurts, waking up every few days to eat from their store and take care of themselves. That makes them super early risers. They even mate as early as February. That said, chipmunks have also been reacting to warmer winter temperatures. According to a Fordham University study, chipmunks in warmer areas are less likely to hibernate at all, prompting them to leave their nests before food is readily available -- and when hungry predators are on the prowl.



Grizzly BearGrizzly bears are a subspecies of brown bear native to North America. They live inland rather than on the coast (like their Kodiak bear cousins) and only hibernate every few weeks. Their body temperatures in this state are warmer than any other hibernating mammal, dipping to only 88 degrees Fahrenheit -- about 12 degrees below their usual internal body temperature. Grizzly bears are omnivores and they utilize between 2-5 months of hibernation to avoid cold weather-induced food shortages, depending on the cold temperatures and amount of snow. Grizzly bears usually emerge from their dens in early March to find food for themselves and their cubs, who can be born as early as January. Unfortunately, as we’ve seen with both groundhogs and chipmunks, warmer temperatures are wreaking havoc on this hibernation pattern, too. The National Park Service confirmed sightings that all 150 of Yellowstone’s grizzly bears were on the move February 9 this year -- a full month earlier than they’re supposed to be awake. Those bears are searching for food that isn’t available yet, prompting them to move further outward in their territories -- and putting both themselves and humans in danger.


Hedgehogs are champions of hibernation. They usually begin hibernation in late October (or whenever the temperature drops below 73 degrees Fahrenheit) and wake up in late March or early April. If winter temperatures are mild -- as they have been in the last few years -- hedgehogs can be spotted in the wild as late as November and December. Hedgehogs are also unique in that they change den locations in the middle of their hibernation if their nest gets too cold. Due to rising global temperatures, hedgehogs have been waking up earlier and changing dens more frequently, putting them at risk of attack from predators. Domesticated hedgehogs attempt to hibernate, too, but should be prevented from doing so by being kept warm and well-fed.

While climate change may be having an outsize effect on hibernating animals, let’s not forget the biggest factor helping animals thrive both during and after hibernation: mothers. Mothers often care for their young during hibernation, and that means everything from keeping them warm and making sure there’s enough food, to protecting them from potential predators. Humans even invoke this behavior in winter months, too, spending lots of time keeping kids warm and dry (especially with all this snow!). Since humans have the longest gestation period of any species on the planet (18 years. Not including any kids who come back home after college), it only makes sense we share this behavior with our fellow mammals every year.

So celebrate the amazing women in your life on International Women’s Day the same way Nature does: cuddling up against the cold. And remember: Spring is coming!