We have much more to do and your continued support is needed now more than ever.
Surviving the Snow: The Amazing Adaptations of Three Winter Wonders
When the temperatures start to drop and the days get shorter, it’s easy to assume that the natural world goes into a state of hibernation. But the truth is that many animals are perfectly adapted to survive the winter months, and in fact, winter can be a time of great activity in the natural world. In this blog, we’ll be exploring how three North American native species—the American dipper, American pika, and arctic cod—are able to survive in below-freezing environments without the aid of hibernation. From dense insulating feathers to systemic antifreeze, we’ll explore some of the amazing adaptation these animals use to keep warm—while keeping busy!
According to the naturalist John Muir, the American dipper is “inseparable” from its stream habitat, and indeed, these birds are rarely found far from rushing water—even during a cold, snowy winter.
The American dipper (Cinclus mexicanus) is a small, semi-aquatic bird that is found in cold, fast-flowing streams and rivers throughout the western United States and Canada. Its most distinctive trait is its frequent up-and-down bobbing motion, known as ‘dipping.’ Scientists believe this motion is used to triangulate prey while feeding in streams, or to camouflage itself against turbulent water.
In addition to their distinctive dipping motion, these charismatic birds are also known for their vigorous feeding behavior, which involve jumping or diving into fast-flowing water in search of invertebrates even at ambient temperatures well below freezing. Dippers typically stay underwater for 5-15 seconds, but can hold their breath for up to a minute.
To survive in this demanding environment, American dippers have a number of incredible adaptations. One of the most important is their dense feathering, which provides excellent insulation and enables them to maintain a normal body temperature even at low air temperatures. In fact, American dippers can have over 6,000 body feathers while most birds of similar size have under 3,000. These feathers have better resistance to water penetration than those of other land birds, allowing them to keep dry even while swimming.
But what about their featherless feet? When the air temperature drops, these birds are able to crouch over their feet and cover them with belly feathers, reducing heat loss. In addition, dippers take advantage of a physiological process called countercurrent blood flow, in which the blood vessels in the feet are arranged in such a way that warm blood is kept close to the surface of the skin, while cold blood is kept deeper down. This keeps the exposed surface of the legs warmer.
American dippers also have a low surface-to-volume ratio, which means that they have a relatively small body size in relation to their volume. This helps them to lose heat more slowly, conserving body heat in cold water. Together, these amazing adaptations allow this tiny, active bird to fly, dive, and thrive in temperatures as low as -22 °F (-30 °C)! Enjoy a serene winter moment with an American dipper:
Despite their cuddly appearance, American pikas (Ochotona princeps) are among North America’s toughest animals. These small, rodent-like relatives of rabbits are native to the western United States and Canada, and are able to survive their entire lives in the alpine terrain above tree line.
Unlike most other mammals, pikas do not migrate away from the mountain tops to avoid extreme freezing temperatures, and they do not hibernate either. Instead, they have an unusually warm resting body temperature of 105 ° F (40.6 °C), which allows them to tolerate the cold. In fact, pikas do not handle the heat well at all, as their resting body temperatures lie within only a few degrees of their lethal maximum temperature, 109.4 °F (43 °C). These animals are so adapted to cold climates that they can die from brief exposures to temperatures as low as 79 °F (26 °C).
To survive in cold temperatures, pikas have a number of physical adaptations to help them. They have furry paws to keep their toes warm and provide traction in the snow, and their thick coat of fur provides excellent insulation against the cold. Unlike the rabbits they are related to, their ears are short and rounded to prevent the possibility of frostbite. In addition, pikas have a high metabolic rate and low thermal conductance, which means that they generate a high amount of heat internally and lose it slowly. This helps them to maintain a constant body temperature and survive through the winter.
Behaviorally, pikas are also well-adapted to surviving these extremes. Pikas spend the entire summer collecting flowers and stems to be stored and dried within their rocky burrow, and these reserves can be eaten during the harsh winter months when food resources are scarce.
Once winter hits, pikas spend much less time foraging and more time in rocky burrows, where the thick snowpack above acts as a warm insulating layer—much like a massive blanket. Because of this reliance on a snowpack ‘blanket’, pikas actually thrive in locations that have comparatively long, brutally snowy winters more so than they would in a habitat with mild winters!
It is important to note that pikas are facing threats from climate change, as rising temperatures may cause them to lose their winter snowpack habitat. This could have serious consequences for pika populations, as they rely on snowpack to insulate their burrows to survive the winter. By studying and understanding the unique adaptations that allow pikas to survive in cold environments, we can work to protect these amazing animals and the ecosystems they inhabit. Enjoy a serene winter moment with an American pika:
Arctic cod (Boreogadus saida) are a unique and vital species that inhabit the icy waters of North America’s arctic regions. These small, silver fish are found in a variety of habitats, including open and nearshore waters, shallow and deep waters, and river mouths. They are even found inside the arctic pack ice—making them the only fish species to live in such a harsh and frigid environment!
But wait—how can a fish live in freezing temperatures? Wouldn’t the water be frozen? It turns out that because the salt in ocean water disrupts the formation of ice crystals, the waters of the arctic can reach temperatures below freezing before hardening into ice. Typically, arctic sea water freezes when it reaches a temperature of about 28.8 °F (-1.8 °C).
Remarkably, arctic cod are able to thrive in these chilly waters thanks to high levels of antifreeze glycoproteins (AFGPs) that circulate in their blood. Normally, when ice crystals form in an animal’s body, they can puncture cell membranes and disrupt the normal functioning of cells, leading to tissue damage and eventually death. AFGPs work by binding to the small ice crystals that form in the body and preventing them from growing into larger ice crystals. AFGPs effectively lower the freezing point of water within the animal’s body, allowing the fish to remain active and forage for food even in sub-freezing temperatures.
Arctic cod are a fascinating and resilient species that are adapted to survive in some of the coldest environments on Earth. Witness the rare sight of a young arctic cod’s heartbeat as it rests in near-freezing water:
Winter is a tough time for many animals, but some species have truly impressive adaptations that allow them to thrive in even the coldest conditions. Species like the American dipper, American pika, and arctic cod have adopted incredible strategies to survive in the most frigid of habitats, all without the aid of migration or hibernation. From extra feathers and antifreeze proteins to warm burrows and strategic foraging, these winter wonders have mastered the art of thriving in the cold. So next time you’re bundled up against the winter chill, take a moment to appreciate the unique ways in which other animals have evolved to persist through the snowy season!