In cold weather, bears' near-skin hairs grow longer. Winter bears hibernate. Hibernating bears save energy. Sleeping, they don't need food, water, or the bathroom. Bears cool off by panting, sunbathing, swimming, & swimming.
Big, warm-blooded whales. Whales keep warm using blubber. Animal fat has fewer blood vessels than blubber. Near-polar whales can have a foot of blubber to retain heat. Whales move to warmer waters.
Big cats hunt in the morning and evening and cool themselves in the shade. Sweating from panting. Snow leopards live in snowy regions. Their thick fur traps heat. They can insulate their paws with fur.
Cold-climate deer are reindeer. Warmth from two fur layers. Fine, compact layer next to skin, longer, shaggier layer for insulation. They shed their winter coat in the summer. Reindeer noses warm lung air.
Marsupial newborns are underdeveloped. Opossums make a den with leaves, grasses, and soft materials during the winter. They don't hibernate but stay in their cosy nest. In Australia's heat, Koalas don't sweat.
Wintertime rodents nest indoors. Plant-lined burrows make comfortable dens. Nuts and seeds make them fat. Beavers store fat in their tails and spend the winter in their insulated lodge.
Primates include lemurs, lorises, orangutans, gorillas, and chimps. Sweating monkeys. Shelter and water cool. Most monkey species live warm but hug when cold. Wintertime snow monkeys soak in hot springs.
Warming up is easy for birds. Many birds have dinosaur-like scales to keep warm. Feathers, too. Water-resistant feathers are downy on the underside. In the cold, their feathers trap air. Shivering warms air and them.