Wild In Winter

by Jackie Dzaluk, Lewisboro Land Trust Director

As subzero temperatures descend upon us, we might wonder how our local animals cope.  In some ways we are a bit alike. Warmer coats are the order of the day and some animals, such as the deer have a specialized winter coat made up of coarse straw like hairs that provide more insulation. While we snuggle under down comforters and coats, some birds also grow additional feathers to provide extra layers of warmth. Others, like the smaller song birds, puff themselves up to create more air space between their feathers to add insulation.

And who doesn’t like a cozy space, out of the elements? The Eastern bluebirds gather together at night to share the warmth in dense shrubs, abandoned bird houses and other protected spots. Turtles will burrow deep into the mud of ponds and wake up when it’s all over in spring. Fish swim deep below the ice, in waters saturated with oxygen. Deer will move to hillsides with a southern exposure to catch a few rays. Voles and mice burrow below the ground. Hollow logs become a refuge for squirrels and raccoons who are active all winter. The red fox will wrap himself up around his long bushy tail. And some birds will hit the sky and go to the Southern US, the Caribbean and South America, only returning to breed in the spring and summer.

But nature has even more tricks up her sleeve! The cheerful chickadee, weighing only ten grams, hides its food in hundreds of spots, having planned for the hard months ahead.  And its amazing adaptation is that its brain actually grows new neurons so that its memory can accommodate all this information! At the end of the season, the brain gets smaller and “resets” its memory, erasing information it no longer needs to survive.  In another striking adaptation, the sex hormones of voles drop in the winter, to allow these usually aggressive rodents to live in communities close together. And what about that turtle under the mud?  How does it breathe? It will take up oxygen through its skin.

Other behaviors come in to play only in winter months. Most obvious perhaps are the mixed flocks of birds which band together. Chickadee couples gather in groups of a dozen or more along with tufted titmice, downy woodpeckers, and nuthatches to forage and move about.  This survival mechanism allows someone to be on the lookout for a predator, like a hawk, and to issue a warning.  It is also thought that this makes it easier for them to find sources of food and evade prey. Much like a school of fish, there is safety in numbers.

While many of us experience a degree of torpor in the dark months of winter, some animals literally do come close to shutting down. While the bear will sleep much of the winter away in a den, their body temperature remains near normal, allowing them to wake and react quickly if need be! Woodchucks, chipmunks, bats, and snakes retreat to dens or caves to hibernate. Other animals slow down and sleep spending more time in their dens with occasional forays out and about. Birds, warm blooded (like us,) drop their body temperature up to 15 degrees at night to save energy, a condition known as hypothermia.  The wood frog and spring peeper give it their all and freeze, only to thaw out in the warm of the spring.  

And maybe it’s all just relative. While our Eastern Bluebirds will fly south for the winter months, the Bluebirds of Canada come here to overwinter, finding it warm enough for them!