Now the animals sleep as the world holds its breath

The woods are as still and silent as death

-Chris Ledoux

We have quite a fascination with the weather and the passage of seasons, despite the fact that neither present modern humans with much more than a minor inconvenience or a passing treat. In fact, the weather and seasons are probably the all-time reigning champions of small talk. We have a large and changing industry devoted to forecasting the weather. Children plan their year around summer breaks. Adults plan life decisions ranging from courtship to home buying based on the season. Anyone who has dealt with time series data knows that much of it shows seasonal variation. In fact, armies of government bureaucrats have created complex calculations to deseasonalize economic data. Other economists have found that the climate of a region is one of the best determinants of migration.

I believe our interest in the weather is the result of instinct or biology. I probably couldn’t prove that and, even if I could, I probably woudn’t bother. Regardless, when we look not too far into our history we see humans that depended on the weather for their livelihoods or even survival while they planned every aspect of their lives around the seasons. Such it is with wild animals here in Michigan as the seasons have a profound influence on everything they do.

On the weekend of 22 Feb, I was walking next to a conifer swamp and witnessed something I had seen little of for the last few months: animal life. The chickadees called from the swamp and I looked at deer tracks through the snow on the boundary of the swamp and a clearing. This was true everywhere during the first snows of December. The air was then filled with the calls of the chickadees and their flights as they hoarded away food for the winter. The squirrels did the same and the rabbits crisscrossed the thickets. After each fresh snow, deer tracks littered the ground after a few days.

But then as the snow accumulated foot by foot the animal activity dissapeared. The reason for this is that the calories lost by traveling through the snow exceed that what they gain in food. In fact, for most of the winter deer will run a calorie deficit burning more calories than they consume. First they burn the fat built up under their skin and above their rump and back. Then, after that, they will use the fat inside their body cavity next to their organs. Following that, their bodies will consume the marrow in their own bones. Given the last few warm winters, most of the deer have just survived the most difficult few months of their entire lives. A number of them will not survive, especially the old, the sick, and the injured. As the last of their bodies’ calorie stores are exhaused, and on a particularly cold night, they will search for food and lie down exhausted and bed in the snow. Their bodies will no longer be able to fight off the cold. Every year I find the bones of these deer usually around clearings where they desperately paw the ground for food.

But most will survive. The deer will still feed but they will bed very near or in their feeding areas eliminating the need for travel. In fact, deer in many areas of Northern Michigan winter in cedar swamps which allows them to shelter around these trees and feed on their branches. Part of the reason that the deer herd in many areas of the Upper Peninsula is struggling is due to the maturation of cedar swamps such that the deer can’t reach the branches for food. A few weeks ago I was traveling along a snowbound two track and saw a small doe born last spring crossing from some jack pines into hardwoods. As I drove next to where the deer crossed, I could see her flailing through the snow up to her belly visibly struggling. She looked reasonably healthy despite losing her mother to the weather, the roads, or a hunter. To me she is a miracle of nature. This deer has never seen winter before and has no other experienced deer to guide her. Yet, by instinct, she has survived for several months in an environment that would kill most humans in hours or, at best, days.

On a following day I was near an opening 500 yards away from where I saw this deer. I saw the tracks of a small lone deer along the edge. I assume this is the same deer. The tracks meandered back and forth on the edge of the clearing walking up to each young scrub oak. If I had ventured off into the snow I would have seen where small branches had been nibbled off each one of these trees. Then I saw where she pawed at the ground exposing the ground for her to feed on any remaining plants. I wondered why she chose this spot and then saw that the snow was thinner at this spot well less than a foot deep. The snow is not a constant depth and the deer know to look for thin areas to reach the ground. I wonder about the mindset of this deer. I wonder if she understands that winter will soon be over or whether she believes that this frozen landscape is a permanent curse from which she will never escape.

With the last week of February, the Lower Peninsula saw its first snow melt. Further melts will follow in March and by mid to late March over 50% of the ground will be free of snow. Even last weekend travel across the snow was incrementally easier. I saw more animal tracks in one day than I had seen the past several months. But below these tracks another miracle of nature is occuring as the plants of the forest slowly wake from their sleep. With each warm day, melting snow rushes into the thawing soil and collects at the roots of the trees. The tree roots intake this water and mix it with stored sugars and nutrients making sap. The tree then propels this sap upward near the bark of the trunk, out into the limbs, and into the tips of the branches. Then as the temperature dips below freezing again in the evening, the sap is sent back down into the roots below the frost line. Like respiration, the sap is drawn up and then down again day after day though March leaving sugars and nutrients near the tips of the branches.

The plants have begun their preparations, and these will take months to complete. When they are done, they will be prepared to again ensure their survival and the survival of every wild animal that walks, crawls, or flies through the forest for one more year.

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