Some Ways Mammals Stay Warm In Winter
When temperatures drop significantly, mammals that stay active in the winter have a variety of ways to keep warm, one of which is to have layers of insulation to prevent their body heat from escaping. Often there is a layer of fat under the skin. In addition to providing a source of energy, fat doesn’t transfer heat as well as other tissues such as muscle or skin, and thus helps to insulate an animal’s body. The next layer consists of a short, dense coat of underfur which is filled with air pockets that provide insulation. Lastly there frequently is a third layer of oily, water-repellent guard hairs which excel at keeping out water. They are often transparent and hollow, providing extra thermal insulation.
Voles, mice, shrews and red squirrels use elaborate tunnels systems under the snow to escape cold temperatures and strong winds. Flying Squirrels huddle together in groups to keep warm. Shivering is a warming technique used by many mammals, including humans. And some active animals, like the pictured Gray Squirrel, simply find a sheltered spot in the sun, close their eyes, and soak up the warmth! (Thanks to Jody Crosby for photo op.)
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Shrew Eyes
Shrews have a very high metabolism and spend most of the day and night hunting for food. Subterranean worms and insects are their main prey, which means that a lot of their time is spent in tunnels, where there is little, if any, light. Consequently, shrews have little need for large eyes or excellent vision, neither of which they have.
While the sight of most shrews is probably limited to the detection of light, some species compensate by using other senses, including hearing and touch, to direct them. The Short-tailed Shrew has a well-developed repertoire of squeaks and clicks, including ultrasonic sounds, for navigation and predation. (photo: hair has been brushed aside in order to see eye slit)
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