Animal Winter Survival Tactics
BRR! It’s cold out there! How do the “wiuts” – the wild ones – survive the winter? Time for a winter ecology lesson – a study of relationships among living organisms during the coldest season of the year and how they relate to their environment during this season.
To our New England flora, winter is a time of drought. Most water is frozen underground or on the surface as snow and ice; not exactly easy to sup up into one’s roots. To make matters more challenging, a winter’s drought lasts approximately six months. What to do? Plants and trees utilize one of three basic adaptations in coping with the winter months: most herbaceous plants die, but not before sending forth their seeds. The individual plant may die, however, the specie and genetic material lives on in the next generation. Other herbaceous plants simply die back. The stalk expires but the roots live to sprout again in the spring. Woody deciduous plants and trees, go dormant as do many basal rosette herbaceous plants. Deciduous trees release their leaves in the fall, thereby dramatically reducing photosynthesis, and therefore energy intake and sugar production. Essentially they “sleep” through the winter. Some species such as, the black birch and cherry, do continue to photosynthesize through their lenticels, those little horizontal lines dashing across the trunk. Most confers, or evergreens, drop their needle-like leaves throughout the year in small quantities, but overall stay green in every season. The noticeable exception is the American Larch (Tamarack) which does drop its needles in the autumn. So if you notice a naked conifer and it’s not obviously dead because it’s in a beaver pond, it might just be a Tamarack.
All animals need food, water, shelter, and space. Some animals stick around and stay active all winter because they can get all their needs met. Animals who cannot get their needs met by bustling about all winter, have 3 choices: migrate, hibernate, or go into a deep sleep.
Deep sleepers such as the skunk, raccoon, black bear, and chipmunk wake up every now and again to look for food and defecate. The black bear’s heart rate does drop significantly but unlike the true hibernators, such as woodchucks and big brown bats, black bears can wake up quite a bit faster without taxing their system to the extent it taxes a hibernator to wake up. A woodchuck’s heart rate and breathing slows and while in hibernation will only take a breath once a minute. The energy it takes for a bat to wake up suddenly can be deadly. This is why, at known bat hibernacula, there will be notices against entering during winter months, so as to protect hibernating bats. Snakes go to multi-specie hibernacula; all balled up, they sleep the winter away. Frogs, depending on the specie, sit at the bottom of the pond and go into a torpor, like the green frog, or freeze, like the wood frog. Freeze? Yes, freeze. These amazing little masked bandits of the woods who hop around the duff in spring, have the ability to freeze without dying. This is because their cells flood with an antifreeze of sorts – sugar – a high concentration of glucose in the frog’s vital organs prevents freezing.
Then there are migrants such as warblers and monarchs. There are several species of insectivore songbirds who migrate south to continue ingesting invertebrates. Then there are the resilient insects, most famously the monarch butterfly and the green darner dragonfly, who also migrate south for the winter, generating a multi-generation migration south and north.
Those animals who stay here and active in winter must find food – either twigs, berries, seeds, or flesh. Chickadees shiver to stay warm, consuming seeds aplenty during daylight. On really frigid nights they will go into a torpor, lowering their body temperature by 18-22 degrees. Crows congregate by the hundreds in winter flocks on roofs and treetops for warmth and safety from owls, then hunt and scavenge the byways while the sun shines. Flying squirrels snuggle together by day and glide through the forest by night. Deer bed down, chewing their cud from bark they stripped, and wander the fields at dusk and dawn. Coyotes yip and sound off before silently stalking the shadows. Otters slide in the snow and hunt for fish in the icy streams. Humans slumber in flat nests in insulated structures then transport themselves in mobile dens to other shielded roosts where they keep themselves busy gathering food from cold lairs. See, as different as we are, we are also in so many ways, similar. All just doing our best to get by, keep warm, and find food.
Arianna Alexsandra Collins, naturalist, poet, writer, and wild edible enthusiast lives in Ashfield, MA.
Into the Outside is a bi-monthly feature in the Ashfield News and Shelburne Falls & West County Independent. This article appears in the January 2017 edition of the Ashfield News.
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