A look at wildlife survival tactics
We assume they go somewhere to the coast of Alaska where it’s more humid and winter is shorter,
Shyloh van Delft
Yukoners know how to cope with winter. We fill our freezers, cozy up by the wood stove, and thaw our frozen feet on unsuspecting loved ones. Animals have strategies too, but for them, it’s a matter of life or death. To survive, they migrate, adapt, hibernate or do a combination.
The real snowbirds
Just like the “snowbirds” among us who head to Arizona and Mexico, some animals–especially birds–know the best way to deal with winter is to avoid the worst of it altogether. Migration is the seasonal movement from one habitat to another for the sake of avoiding harsh weather, or finding more abundant food or a better place to raise young
Most trumpeter swans, for example, are already on the temperate coast of Washington or British Columbia after breeding in Alaska or the Yukon over the summer.
Bats are a more mysterious migrator. After a frenzied summer eating nearly half their weight in insects every night, they say adios in September. As to where they go, experts aren’t sure, says Shyloh van Delft, a project technician with the Department of Environment’s bat monitoring program.
“We assume they go somewhere to the coast of Alaska where it’s more humid and winter is shorter,” she says. The department bands bats with the hope that they will be recorded outside the Yukon. So far, no luck.
Wherever these nocturnal mammals spend winter, they’re not in the sky. After little brown bats migrate, they hibernate to conserve energy while food is scarce.
Still other animals migrate within the North. Porcupine caribou travel between the Arctic coast in the summer, where there is ample forage (food), to their winter range further south (in the Yukon, roughly between Old Crow and Dawson City).
“They need to move to find adequate forage and get out of harsh weather conditions,” says Mike Suitor, the department’s North Slope and migratory caribou biologist. He says in winter, these ungulates are focused on eating caribou lichen, digging through snow of various depths to get at it.
Adapt, or else
Wildlife that live in the north all year have physical or behavioural traits that help them stay warm, conserve energy and travel on snow. Their fur traps the heat, deflects wind and repels moisture. Some, like ptarmigan, hare and ermine, undergo a colour change for increased camouflage.
Animals that travel more widely in winter have larger feet for more efficiency on snow, like lynx and caribou. And many will build up food stores so they can burn fewer calories and be less exposed to predation. Pika spend the winter under talus rock piles in the alpine, surviving off their stockpile of plants collected in late summer. Beavers similarly keep a mound of willow and aspen close to their warm lodge.
A very long snooze
Still other animals go the “Sleeping Beauty” route. Hibernation is when an animal’s metabolism and body functions slow down to conserve energy. When bears go to sleep in their dens, their heart rate decreases from about 50 beats a minute to 10, and they generally don’t eat, drink or defecate, although they will wake and shift positions. Impressive, but Arctic ground squirrels are nature’s ultimate sleepers.
“They are the world champion hibernators,” says Tom Jung, senior wildlife biologist. “As soon as it gets a little bit nippy, they dip down into their burrows and that might be as early as late July for the adult males. And they don’t come out of hibernation until early April.”
Jung says these chatty rodents hibernate longer than any other mammal in the world. Their body temperature also dips to -2.9C, colder than any other mammal in hibernation. Although their brain doesn’t freeze, their heart beats only about once every 45 minutes.
“It’s incredible they can do that,” Jung notes.
Although northern wildlife is well-suited to our climate, winter is still tough, and many will succumb. That puts human “survival” chores like shovelling snow and chopping wood into perspective. If you can have a mug of hot chocolate after, it’s not that bad.
If you’ve read this far, you’re on your way to acing beginner wildlife trivia on Nov. 27. Find out about that and other events hosted by Yukon Wildlife Viewing at Yukon.ca/wild-discoveries.
