A Long Winter’s Nap
Wildlife nestle in for the season during hibernation, a cold-weather survival tactic.
When frost sets in and food disappears, non-migratory animals that depend on summertime insects and plants find a sheltered nook and slow things down—way, way down. Breathing, heartbeat and even body temperatures ease to a bare minimum in winter. Hibernation lasts several months and allows wildlife to survive freezing temperatures and conditions.
Winters are tough for many warm-blooded animals, especially when food sources are slim, which is why hibernation is so important. To prep for their seasonal slumber, mammals such as groundhogs, bats and bears gorge for weeks in fall to fatten up. Once heart and respiration rates slow, body temperatures drop and less overall energy is used, those fat reserves last for months.
Animals that hibernate are often hiding in plain sight. For example, bats settle inside manmade shelters—church steeples, attics and the walls of houses— but you can find them in natural caves and tree cavities, too. Some animals that hibernate, including chipmunks, are light sleepers. Although they pack on the weight before winter hits, they also fill an underground storehouse to nibble on throughout the season.
Hibernation isn’t just for warmblooded mammals, though. Toads, frogs, salamanders, turtles and snakes all hunker down against winter’s chill. Toads and tree frogs burrow deep into the soil, while spring peepers, wood frogs and spotted salamanders seek out crevices in logs or rocks, or snuggle below a thick layer of leaf litter. Once these cold-blooded creatures are safe and sheltered, their bodies start pumping out glucose, a natural antifreeze that prevents their cells from dehydrating as temperatures drop below freezing. Even more incredibly, their breathing and heartbeats may stop completely. Only their brains maintain minimal function as they wait out the winter.
The survival strategy of aquatic bullfrogs, snapping turtles and other water-loving wildlife is to dive deep. They settle on the bottoms of ponds where the water doesn’t freeze. Frogs sometimes bury themselves in mud to hibernate, leaving their nostrils exposed, and turtles breathe through their skin, even if completely submerged in mud.
The garter snake that’s been in your backyard all summer slithers off to an underground communal den, where it joins dozens to hundreds of its kind to pass the winter. Even land snails sleep through winter, sealing up the openings of their shells after they retreat into nooks and crannies or under dead leaves.
Sally Roth looks forward to her backyard black bears going into hibernation, so she can put her bird feeders back up at her home high in the Rockies.