Now that winter is gradually setting in, have you noticed how quiet it is outdoors? It is because local wildlife inhabitants from the plains to the mountains – badgers, snapping turtles, ground squirrels, grizzly bears – are conserving energy and migratory song birds have headed off for the winter.

In warmer months when plants, small animals and insects are abundant, most wildlife can easily refuel. In winter, their survival may require less activity, storing food in caches, going dormant or even hibernating.

“Every species has its own set of unique winter survival skills. They may migrate, hibernate or simply move around less to balance their energy expenditures with limited food sources,” said Kim Annis, Montana Fish, Wildlife & Parks bear management specialist in northwestern Montana. “The result is that unique quiet in the outdoors that is so much a part of this time of year in Montana.”

Annis said non-hibernating species, including shrews, mice, voles and other small rodents, conserve energy in the winter by storing foods in a cache and by communal nesting to conserve body heat.

Other wild creatures have adapted to extreme cold and a restricted food supply by going into a deep sleep, others by hibernating.

Raccoons, skunks and badgers are among the deep sleepers. During the coldest months and deepest snows they go into a deep sleep or “torpor,” that slows their metabolism. They periodically wake up, and may even hunt for food before they go back into this deep sleep.

Hibernators include warm-blooded ground squirrels and marmots, and cold-blooded snakes, turtles and frogs. They go into a deeper state – with extremely low body temperatures and heart rates and respiration at a fraction of normal. For example, some sources say a hibernating marmot’s heart rate can slow from about 80 to four beats per minute, and its temperature can drop from about 98 degrees to as low as 38 degrees.

To hibernate, turtles and frogs bury themselves in mud below the frostline or the mud and debris at the bottoms of ponds. A ground squirrel hibernates in its den for a period of five to six months, but wakes up every so often to eat from its cache of seeds, grains and nuts stored inside the den.

“Bears have amazing winter survival skills, though they are not deep hibernators,” Annis said. “Grizzly and black bears experience a winter lethargy where a bear's body temperature drops to about 10 degrees Fahrenheit below normal, and its respiration and heart rate decrease.”

Bears den during this time, but denning is delayed if food continues to be available, she said.

Annis said denned bears do not become dehydrated even though they don't have access to water. A bear's body is also able to process urea, a main component of urine produced during tissue breakdown, into new protein. A bear’s cholesterol is very high as it lives off of its own fat, but bears do not suffer from hardening of the arteries.

“It may be quiet outdoors in winter, but there are many wild creatures nearby conserving their energy in order to survive the winter,” Annis said. “We can help by not disturbing them in any way.”

For more on Montana's wildlife, see the FWP Web site at fwp.mt.gov for the “Animal Field Guide.”

(Diane Tipton is the statewide information officer for Montana Fish, Wildlife & Parks).