Storing the barbeque, putting up storm windows, checking the antifreeze in radiators, and pulling out heavy coats and sweaters — such activity abounds as humans prepare for the advent of winter. Other animals also use a wide variety of techniques to prepare for colder weather.
Winter usually brings two challenges to wild animals: a drop in temperatures and a drop in food supplies.
Squirrels storing nuts and seeds for winter is a common image for autumn. In fact, many small mammals collect and store food when it's abundant. A few birds also set aside food: acorn woodpeckers store acorns in holes drilled into oak trees; shrikes have been known to leave prey impaled on thorns for later dining.
However, most stored food is probably not collected by the animal that gathered it. There is evidence that small mammals often simply forget where they left their hoards. Stashes are often pilfered, or they rot — or perhaps sprout.
Storing fat is another common mammalian alternative. Fat combines the benefit of food storage with insulation. Even humans exhibit this trait as many people experience an increased craving for starchy foods in autumn and winter.
Mammals also usually put on extra fur, further bolstering the insulation. A few animals, such as snowshoe hares, ermines, and willow ptarmigans, change the color of their fur or feathers to blend into the new, snowy surroundings.
Famously, many birds — and certain mammals — migrate towards the equator to warmer climes. Some, like our spotted towhee, move to lower elevations. If you've noticed that robins look different in the winter, you're right: Our summer robins spend the winter in central California while Canadian robins take their places in our yards.
Most amphibians seek sheltered nooks under logs and other protected places, applying the same principles we do when mulching garden plants to insulate against frost damage. You may have noticed mice and ladybugs entering your home as they seek warmer quarters. Some animals, penguins, for example, may huddle together in large groups in wintertime to conserve heat.
True, prolonged hibernation is rare in western Oregon since our winters are not particularly severe. Many of our species, from bears to frogs to some bats, do become torpid for short stretches in winter, experiencing periods of lowered metabolism. Not being in a deep hibernation allows many groggy creatures to take advantage of a sudden warm spell. (Note that disturbing bats in winter forces them to use up so much stored energy that they may starve before spring.)
Perhaps the ultimate adaptation to the challenges of winter occur in the insects that have adjusted their life cycle to accommodate the cold season. In many species the adults die in autumn, leaving eggs or larvae in cocoons to lie dormant through the winter. Further, some insects undergo a chemical metamorphosis that alters their blood to make it resistant to freezing—animal antifreeze!
While our mild Oregon coast winters may not elicit a "batten down the hatches" approach to the coming chill, many of our residents still move around, store up, bundle up, slow down, hunker down, and huddle together to brave the season.
For information on how you can arrange an exploration of our fascinating natural history, contact Marty at 541-267-4027, firstname.lastname@example.org, or www.facebook.com/wavecrestdiscoveries. www.wavecrestdiscoveries.com
Questions and comments about local natural history are welcome; gift certificates are available.