Wildlife cope in cold weather

Some animals are heavy hibernators, others light sleepers

There’s no need to rescue wildlife, even in winter.

Naturalists with the Missouri Department of Conservation say although winter is a challenging season for wildlife, each species has its own method of surviving the cold. Some migrate, some hibernate and others simply den up and stay warm.

Jordi Raos, a naturalist at the Cape Girardeau Conservation Nature Center, said woodchucks, or groundhogs, are considered true hibernators. In late summer, they fatten up to prepare for a deep sleep that usually lasts until winter is over. They conserve energy while sleeping by lowering their body temperature by half and their heartbeat down to four or five beats per minute from the normal 160.

“Other true hibernators include Franklin’s ground squirrels, meadow jumping mice and some species of bats,” Raos said.

Though bears are widely thought of as hibernators, they aren’t true hibernators. A bear’s sleep is not as deep as a groundhog’s. They fatten themselves before winter and their heart rate drops, but their body temperature doesn’t go down much.

“This is probably because black bear females are usually pregnant when they sleep, and the babies growing inside them need warmth,” Raos explained. “Bears can even nurse in their winter dens.”

Frogs, snakes and turtles don’t hibernate, but they go into what’s called torpor, or a dormant state that closely resembles death. Green frogs spend winter in the mud at the bottom of ponds and box turtles bury themselves in soft ground.

Snakes find shelter in a den or crevice and may spend the winter in a tangle of other snakes, sometimes not all the same species. Some frogs, including Missouri’s wood frog, deal with lower temperatures

“This is a great time to take a hike or go out in your yard to look for tracks, scat and chew marks to see who’s been out and about.” — Jordi Raos, Cape Girardeau Conservation Nature Center

by becoming slightly frozen. The livers of these frogs secrete a sugary substance that allows them to freeze without dying.

Skunks, raccoons and opossums don’t hibernate, but will nap in dens, trees, or logs during the coldest parts of winter. Their naps might last weeks, but when the weather turns balmy, they venture outdoors. These nocturnal animals may also switch to searching for food during the day to avoid colder night temperatures.

“This is a great time to take a hike or go out in your yard to look for tracks, scat and chew marks to see who’s been out and about,” Raos said.

The department’s online field guide can be found at www.mdc.mo.gov.