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Active animals in icy alpine

Sarah Hockensmith
Tahoe Institute for Natural Science

As humans, we have the luxury to heat our homes, put on a warm hat, or blow our driveways to combat the relentless, frigid winters. Other animals, however, do not.

This begs the question, how do they survive such brutal temperatures and conditions? Some animals, like the Belding’s Ground Squirrel may avoid the frost entirely by hibernating up to nine months of the year. On the other hand, other fauna aren’t strictly “true Tahoe locals” and instead migrate to other locations that provide easier living through the winter months.

These aforementioned strategies are no easy task and require preparation and specialized adaptations, yet, not all critters avoid or sleep through the harsh temps. There is a select group that take the winter head on, utilizing their individualized methods of toleration to stay active and survive the frosty alpine conditions.



Tahoe hosts over 320 recorded bird species that either live in, travel to, or pass through the region, but only about 20% of those will stay year round.

Mountain Chickadee on an icicle.
Will Richardson/ TINS

Some permanent residents include woodpeckers, nuthatches, ravens, Steller’s Jays, and Tahoe’s favorite, the Mountain Chickadee. Like other birds that stick around, the Mountain Chickadee is able to do so because they have the ability to find food in the freezing months.



These small birds can be found feeding in the icy trees, searching for frozen insects in bark and pine needles. Additionally, chickadees and other birds like Steller’s Jays and Clark’s Nutcracker spend the warm months caching (hiding) food throughout the landscape. When insects and seeds become scarce in the winter, they rely on consuming their pre-frost stashes to maintain their energy to stay active and withstand the cold.

Ptarmigan can be found feeding in the icy trees, searching for frozen insects in bark and pine needles.
Will Richardson/ TINS

Similar to the birds, if an American Beaver had one piece of advice on how to survive winter, it might be that preparation is key. Busy beavers, as one might say, spend their spring, summer, and fall building their lodges and dams, felling trees for food and structure, and creating entrance paths to their homes to protect themselves from predators.

These preparations allow beavers to stay active year round, retreating to their dens for safety, food, and a cozy place to wait out the winter chill. Beavers have a multitude of adaptations for their aquatic lifestyle, such as webbed feet and a third clear eyelid that acts like goggles underwater, and putting on a very thick and waterproof pelt in the chilly months.

Beavers have coarse, waterproof hairs that bond together like a zipper to keep water from chilling their skin. Additionally, they produce oil from castor glands, which they rub throughout their pelt as a waterproofing agent keeping them dry, warm, and productive all year.

Beavers aren’t the only animals that rely on their pelts to survive. Five Tahoe animals not only rely on the warmth and insulation of their feathers and fur, but also their ever changing appearance. The Long-tailed Weasel, Short-tailed Weasel, Snowshoe Hare, White-tailed Jackrabbit, and the White-tailed Ptarmigan (a glorified snow chicken) are the fabulous five that transition from earth tone colors in the non-snowy months to white in the winter.

This transformation is triggered by photoperiod, or the number of sunlight hours in a day. As sunlight hours become fewer, the shorter photoperiod prompts hormonal changes which cause these animals to molt their fur and feathers. These new coats of fur and feathers grow in white as a result of the slowed production of melanin (pigment), creating a perfect camouflage in the snow.

Temperature fluctuation or even snowfall has little effect on this process, so in years when Tahoe does not receive the normal snowpack anticipated on our mountaintops, these animals will change color anyways, and can stick out like a sore thumb magnifying yet another reason of the importance of snowpack in the Sierra Nevada.

Lastly, one Tahoe species that has proven to be incredibly adaptable to both winter environments and a wide range of habitats are Coyotes. These canines spend the months of winter scarcity searching for prey in the subnivean zone; a hollow area between soil and snow that remains a steady 32 degrees fahrenheit, serving as a protective refuge for active small mammals.

Their excellent canine sense of hearing allows them to listen for movement from voles, mice, weasels, and other prey scurrying underfoot. Without ever sighting the object of their hunt, Coyotes dive headfirst into the snow to catch their food, allowing them to consume calories year round. Although Coyotes don’t have many predators to hide from, their thick fur helps them stay warm, just like the beaver, weasels, hares, and many other winter tolerators.

Animals utilize preparation, physical adaptations, and their wits to stay active year round. These local animals’ strategies bring us back to the question posed above. Perhaps instead of asking how animals survive such brutal temperatures and conditions, we should be praising them on their ability to thrive.

If you would like to learn more about Tahoe’s natural history, come explore with the Tahoe Institute for Natural Science by joining us on one of our many free nature tours. All tours are free and open to nature enthusiasts of all experience levels. To learn more, visit us at http://www.tinsweb.org.

 


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