Early Winter Arrives
And now it’s November…..
My dog walks recently have the added moments of the dog patiently waiting as her slow human adds layers of clothing; boots, neck gaiter, headband, mittens, and a jacket. Stepping outside in summer shorts, t-shirt, and sandals in November weather would be a very uncomfortable, even painful, experience, so we humans adapt to the temperatures with human-designed equipment. We humans take our winter preparation further as we decide if our snow tires are up to another season, get the furnace tuned up, winterize the outdoor plumbing, pull out the shovels and snowblower, and get the deck furniture into storage. While we often grumble about the work this all involves, these are our adaptations and we survive the cold.
While we are distracted with our own preparations, we might not notice the similar activities going on around us in the plant and animal realm. There are four main ways the natural environment manages the months going into winter: Migration / Hibernation / Dormancy / Adaptation
Migration -
There are many humans who have the means to simply head south during the cold months. These ‘snowbirds’ get their cues from the wildlife doing the same. The pond has frozen over and so the ducks have headed south to waters that are still flowing. Hummingbirds head to warmer climes and many of our feeder birds such as Grosbeaks and Western Tanagers we won’t see until May or June. Having wings means that the length of migration can be greater, thousands of miles even. Hawks will move down to the prairies for easier hunting with a lesser snowpack. Certain species of insects like some butterflies and dragonflies will migrate long distances as well. If leaving is an option, then it is usually the easiest option.
For those creatures without wings, they may still be on the move. Larger animals like elk, deer, bison, bighorn sheep, and moose may move from deep snow areas down to a lesser snowpack on sunny, south-facing, slopes and running water, over the course of the winter. While not thousands of miles, it is a significant shift. Moving to where the food is available is a strategy that works. It’s an adaptation that even humans use, in winter or not.
Hibernation -
The ‘sleep-it-off’ method takes on many gradients of activity and alertness. From the short-term ‘hibernation lite,’ called torpor, where the animal’s temperature and metabolism are reduced for 24 hours or less, to Wooly-bear Caterpillars (Isabella Tiger Moth) who freeze solid (diapause) until spring. Bears are well known for hibernating, but it is more of a torpor, they can wake for periods of time and even leave their dens to find food before returning to their deep sleep or waiting cubs. Snakes go into a mode called brumation, where they don’t move, but are not quite hibernating. They are so motionless that they don’t need food energy to stay alive, so they ensure not to go into this state with anything in their stomachs. Food in the stomach that isn’t digested will rot, and then, well, ugly things could happen. Snakes do need to keep to a minimum of warmth though, and will then band together for this brumation, even snakes of different species, to ball together and keep each other warm in an underground burrow. Amphibians, turtles, frogs, and salamanders, will burrow under the mud of a pond to hibernate and some species can even fully freeze and then thaw in the spring.
Dormancy -
We watch the process leading to dormancy each Autumn as the leaves change color and fall from their trees. As temperatures move to consistently below freezing, the trees will go into a dormant mode, not growing, not producing sugar energy via photosynthesis and they will move water from inside their cells to the spaces outside the cells preventing the tree cells from freezing. Some trees, such as the Quaking Aspen, can still photosynthesize through their bark, but on a reduced energy budget. The trees wait out the winter until longer days of sunlight and warmer temperatures signal them to grow once again.
Adaptations -
Ah, here is the best of them. Those creatures that have evolved to survive the seasons. You might leave, you might sleep, but those that make the best of the ‘low resource’ season see it through and often thrive. Some of the adaptations involve a change of color. Rabbits, ptarmigans, and ermine who wore brown fur coats in the summer change to white in the winter. Better to hide from predators. Squirrels, who have worked all year to preserve stores of nuts, pinecones, and seeds can rest in their snug winter houses surrounded by soft, heat-storing feathers and fur tufts. Those birds who have stayed have stores of small food caches all over the forest. Chickadees are actually so good at remembering all these locations that their brains will grow in size in the early winter months. As they use their stores and no longer need to recall the locations, their brains slowly return to their summer size by spring.
And then there are the moles, voles, and shrews. With a maze of underground tunnels well below the frost line, they are comfortable in their dark domains. What storybooks like Wind in the Willows and Redwall don’t tell you, though, is that moles keep a dungeon of sorts for their winter food. Separate rooms are formed to hold the paralyzed, but still alive! bodies of worms, beetles, and snails so that the mole can have ‘fresh food’ when they want. Using toxins in their saliva, the moles bite their perspective meals, paralyzing them for storage. How’s that for a Halloween story?
We’ve only just scratched the surface on the ways that the natural world moves into winter. While you are contemplating the tread depth of your snow tires, be sure to look around outside as well. There’s a whole lot going on as winter sets in.
Sources:
- https://paragonguides.com/winter-brings-wildlife-to-the-valley/
- https://cwhl.vet.cornell.edu/article/wildlifes-winter-preppers-and-more
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