Catching a glimpse of these little guys is always a that never lasts long. This is an ermine. Their coat turns from brown to white each winter, allowing them to be nearly invisible as they move through a snow white landscape. Their tail has a black tip on the end, which functions as a decoy luring any potential predators to strike there, rather than a more vulnerable part of the body. 


Winter Wildlife Feature III - River Otters

There is little question that the next species in my series of winter wildlife finds the most creative ways to have fun. Humans aren’t the only ones enthralled with the feeling of sliding on snow. While we use skis, boards, or sleds, river otters need look no further than their long and slender bodies. When on land, otters cover ground with a hop, hop, slide, hop, hop, slide movement pattern. Sliding on the snow and ice certainly allows them to travel more efficiently, but spend any time with otters and there’s no denying the routine is as much, if not more, for fun as it is for practicality. 

Yellowstone River Otters
River Otters Sliding

Other than playful antics to keep their mind off the cold, otters have some impressive adaptations and strategies for winter survival. River otter’s lengthy guard hairs, and dense underfur, which traps insulating air, keeps them warm in extreme temperatures. On top of that, oil secreted from the sebaceous gland actually waterproofs their coat, preventing water from reaching their skin. To remain well insulated they must replace the air in their underfur after swimming, and they do this by rolling around in the snow, and yes, you’ve guessed it, playfully. 
Since the water temperatures are warmer than the air, otters opt to spend more time underwater. They will often travel and hunt underneath the ice shelves which line the rivers and creeks during winter months. An otter may stay below the ice indefinitely by breathing in the air pockets trapped beneath the ice.

River Otter Swimming

Winter Wildlife Feature I - Bison

Featured first on this series of posts highlighting wildlife and their unique strategies for enduring Yellowstone winter is the bison. Two key assets equip bison to survive in this unforgiving climate. 

Bison in snow

The distinct shoulder hump on their back, which is actually a protruding muscle, allows them to function as a 1 ton, living snow plow. Unlike other ungulates, such as moose and elk, which scrape with their front feet to access food under the snow, bison use this muscle to rock their massive heads back and forth exposing grass and sedge buried under several feet of snow. Some bison will opt out on this “snow-plow” technique, preferring to graze alongside thermal features where the warm steam from geysers or hot springs melts the snow on the surrounding grass. 

Bison in thermal steam

When violent winter storms hit, prompting other wildlife to seek shelter from the chilling wind and blinding snow, bison just plop down where they are and wait it out. Their winter coats are so thick and well insulated that the falling snow doesn’t even melt on their back. In a heavy snow, you can watch the largest land animal North America vanish before your eyes in a matter of moments.

Yellowstone Bison