When autumn gives way to winter, life goes on.

Despite the sometimes frigid temperatures of the season, life goes on.As the snow waxes and wanes in the canyons and on the mountainsides, life goes on.

That is a lesson Adrienne Cachelin, Russ Norvell and other naturalists pass along to students young and old who venture into the Wasatch canyons to learn about wildlife in winter.

Cachelin, education coordinator at the University of Utah's Red Butte Garden & Arboretum, led a Saturday-morning snowshoe hike into the canyon that gives the east-bench reserve its name. Norvell, who is Cachelin's husband and an expert birder, came along to lend a hand - and to pack a tripod-mounted bird-watching telescope.

Their subject was "The Nature of Snow."

"For lots of things, winter is really a hard time to live," Cachelin told those along for the trek. But the animals do. Tracks criss-crossing and paralleling the trail testify to their presence. Occasionally other signs show up: scat and markings; a mussed scene of prints and wing marks that may reflect a life and death struggle between predator and prey; birds singing their hearts out in the tangle of oaks, maples and box elders - and, occasionally, an actual sighting of a winter-white weasel, a mountain lion or a shaggy moose.

Norvell, on a hike with another canyon party, recently got a glimpse of two moose in Red Butte Canyon.

"We wouldn't see moose at this level in summer," Cachelin said. They were probably lured down by the moderate depth of the snow this year and by tasty willows at the edge of an old Fort Douglas reservoir near the canyon's mouth.

"If you're a moose and want water, some of the buds in these plants are great," she said.

There are 39 species of mammals and about 1,100 species of plants known to live in the Wasatch foothills, Cachelin and Bruce Thompson of EcoTracs note in "Exploring Diversity in Winter," a handbook they've put together for students, teachers and others. To survive winter's challenges, plants, animals and insects "follow the MAD rule - Move, Adapt or Die," they note. Moving can involve a change in elevation or a migration. Adaptations range from a change in diet to hibernation. Some plant and insect species die off, leaving survival of the species to the next generation.

Cachelin cautions the members of her party to be as quiet as possible, to try not to spook any animals should they appear.

"We have to remember that we're visiting someone else's home right now," she said. Scaring or otherwise displacing overwintering animals can tax them unnecessarily, forcing them to use up energy they may need to endure. Winter stresses animals in a number of ways: the cold, short days; the lack of drinkable water; the scarcity of food; radiation reflected by the snow.

Being quiet wasn't easy on this atypically mild morning, however. No new snow had fallen in days, and what snow there was had a dry, crunchy texture. Stepping on it sounded like walking on cornflakes.

"We won't be sneaking up on anything today," a snowshoer commented.

A dozen people signed up for this particular jaunt. Red Butte Garden arranged to have the proper number of snowshoes available - but as the trek progressed, it became obvious that the planks were not needed. What snow there was turned out to be hard and supportive. The party eventually left the snowshoes behind.

The trekkers included participants from those in their teens to a few in their senior years. Most were adults in their 20s and 30s. The majority were Utahns, but a few were from out of state. Cachelin asked all why they'd decided to come along.

Young Chris Sheppard of Salt Lake City said he was there because his sister Angela wanted a partner.

One woman's sister was involved that day in an athletic competition in Oregon. "I wanted to be doing something outside so I could think of her," she said.

Patty Murphy of Nashville, Tenn., visiting friends in the Salt Lake area with husband Mike, said "It sounded great - a new experience."

For many the lure was the canyon itself, which is gated and into which entry is restricted. Once the watershed for Fort Douglas, 5,200 acres in the canyon are now a preserve - a "research natural area" - managed by the U.S. Forest Service and Red Butte Garden. Much of the vegetation there is very like what would have been found in the area in pioneer times, and as such the canyon is a prime target for study by scientists and naturalists, including weather observers and Audubon Society bird counters.

Those restrictions prompted many of the hike's participants to sign up.

"People always say, `If you ever get a chance to go up there, you should,' " said one man. So he did.

Cachelin began pointing out the hoof-, paw- and claw-prints and trails made by animals and birds, from deer to magpies; the latter could be heard squawking nearby.

She stopped at one trail, pointing out that four-legged mammals tend to put their back feet into the spot previously occupied by their front feet as they proceed through snow.

"Whenever you see one of those eight-toed whatevers, it's an animal stepping into the place where the front feet were," she said. In addition, measuring the distance between two sets of front prints will give an observer "a good idea how big that animal is."

Many of the tinier tracks disappear into the low brush and shrubs.

"A lot of the activity is under the snow," Cachelin said. "Rodents, mice, weasels and such live down by the ground," where temperatures remain survivable even when outside temperatures plunge. The air trapped within the layers "is the insulative value of snow," she said.

A set of prints headed off into some stunted trees. "If you were speculating and saw this pattern," she asked her temporary students, "what would you think this was?"

"A squirrel?" one answered.

Cachelin looked closer, then pointed at the paw prints, "Here, I think it's a rabbit."

In her handbook, she notes that the tracks seen most often in the Red Butte Garden area include those of deer, coyote, mouse, weasel, rabbit and porcupine.

Cachelin kept an eye out for patterns made by big animals and small, from those that walk (she attended to their "stride" and their "straddle") to those that bound or hop. Varying lopes can indicate whether they were headed uphill or downhill. Meanwhile, Norvell, an avian ecologist with the Division of Wildlife Resources, peered along the ridges and into the wooded glades.

"One of the reasons I like to bring Russell along is that he's a birder - he's always looking up and I always look down," Cachelin said.

Indeed, the boisterous calls of tiny birds halted the group.

To Norvell, they were chirping "Phoebe."

To Cachelin, the call sounded like "Cheeseburgers." "Is that projection?" she asked. "I didn't have breakfast."

Something like a conversation was being carried on by a scattered colony of chickadees, Norvell said. Birdwatchers have cataloged nine different chickadee calls. Chickadees maintain breeding colonies, and the calls seem to help them keep track of one another and to delineate their territory.

The birds are not always active in winter. In fact, said Norvell, they can go into a torpor for about three days to preserve energy. This led into a discussion defining "torpor" and "hibernation."

Marmots, which live among high rock fields in the mountains, hibernate. Ground squirrels do too; some are awake only three months in a year. Although bears are often said to hibernate, their winter dormancy is really more akin to torpor, he said.

After a few hours on the Red Butte trail, the party headed back downhill. They stopped occasionally to check out tracks, puzzling over one set made by something larger than a deer - perhaps an elk or a moose. Some trekkers paused to watch eagles flying high overhead.

Back at the canyon mouth, Angela Sheppard said the short winter hike was well worth the time and effort. "I'd recommend that to anyone," she added.

Patty Murphy agreed. "It's just so different here," she said, noting the differences between the snow-blanketed world of Utah and the green hills of Tennessee.

The Murphys came to the Wasatch to ski but leaped at the opportunity to snowshoe and take in a winter hike as well. "We're always trying to do something different," she said. And the mountain splendor gave them the chance to do just that. "It's just so cool."

Cachelin said excursions like this are important to help people understand the precarious lives of the animals and the birds, as well as the importance of protected natural areas like Red Butte Canyon.

This is because, she said, "it is possible to love something to death."

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ADDITIONAL INFORMATION

Anatomy of a snowpack

New snow

Equi-temperature metamorphic snow layer

Possible temperature-gradient metamorphic snow layer

Ice crust

Equi-temperature metamorphic snow layer

Temperature-gradient metamorphic snow layer

Ground

Temperature-gradient snow - sometimes called "sugar snow" - is most commonly formed just above the ground surface, according to Bruce Thompson of EcoTracs. These snow crystals can also form above an ice crust or near terrain irregularities, such as rocks or vegetation. Because it affords very little cohesion, it represents a "weak" layer and can be a significant benefit to animals that live beneath the snowpack, seeking food and shelter.