BLANE KLEMEK COLUMN: Winters for wildlife is all about adaptation
I recently spent some time inside a ground blind hunting deer in northwest Minnesota, mainly to escape sub-zero, wind-chill factors and blowing snow. The other reason was to hunt in the open landscape where concealment was critical if I were to go unnoticed by deer either nearby or far away. Surrounded by commanding prairie views in all directions, the tall big bluestem grass swayed in the wind, even making noise as the stiff golden stalks and seed heads knocked against one another. The sight was mesmerizing—open countryside, prairie grass taller than my blind, and the blowing snow. I was glad I was inside the relative warmth of the flimsy nylon pop-up blind.
One mid-morning while alone and far from wildlife of any kind—or so I thought-- I was suddenly surrounded by a large flock of dark-eyed juncos and a few scattered song sparrows mixed in here and there. It surprised me when the flock descended from seemingly nowhere and alighted onto the hard-packed snow within the tangles of the waving big bluestem grass. At first I thought the birds were simply there for the shelter the grass afforded them, but I quickly discovered the real reason—food.
Soon after the flock had settled, every bird began in earnest to forage on the seed heads of the swinging grass. In some instances stalks were already laying horizontal on the snow and provided ready access to the seeds contained inside the heads, and in other instances birds hopped and flew to reach vertical seed heads to momentarily perch on the undulating grass stems, where they quickly struck seeds with lightning strikes of their beaks.
The whole spectacle lasted for many minutes as I sat and enjoyed the show. Both species of birds, juncos and sparrows alike, fed side-by-side as they expertly husked grass seeds with their fast tongues and beaks, hulls a-flying out of their mouths, consuming the nutritious seeds. And after a while the flock dispersed and left me alone once again. Later, upon leaving my post, I examined the area where the flock had been feeding. Everywhere on top of the snow were remnant seed heads and husks left from the birds' feeding activities.
Relationships between wintertime and wildlife is fascinating. How species of wildlife survive the harshness of winter is something to marvel at. Ruffed grouse and sharp-tailed grouse, for example, actually do quite well in the wintertime when snow is deep enough and of the right consistency for burrowing into. Both species dive headfirst into soft snow to escape the coldest days and nights inside "snow roosts" that can be as much as 50 degrees warmer than the ambient outside air temperature.
Snow is ideal insulation that helps grouse conserve valuable energy throughout the long winter months. Not only do these snow roosts protect them from bitter cold temperatures, wind, blizzards and the like, snow roosting helps keep them hidden from predators, too. Indeed, walking across the prairie last week I discovered more than a dozen sharp-tailed grouse snow roosts.
Change of color
Some species of mammals turn a different color seasonally in order to escape detection from predators and prey alike. Except for the tips of snowshoe hares' and white-tailed jackrabbits' ears, as well as the tips of weasels' tails, which are black, these species of mammals' fur coats are snow-white in the winter. Conversely, their pelage changes to brown in the spring, and by summertime their brown coats blend in with their environment as effectively as do their white coats in the winter landscape.
White-tailed deer are also survivalists. Deer respond to the challenges of winter both physiologically and behaviorally. Nature has provided them with the ability to decrease their metabolism, thereby effectively decreasing the volume of food they need to eat in order to survive during times when food is normally scarce. Fat reserves also help them survive and cope with low food abundance.
Additionally, a deer's dense coat of long hollow, air-filled gray hairs replaces their red-colored, shorthaired summer coat. It insulates against the cold so well that falling snow can pile up on a on a deer's back without it melting because very little body heat escapes through the thick winter coat. And being an intelligent creature, a deer will also use available cover to escape cold winds and temperatures. Deer actively seek out coniferous woods, cedar swamps and other wooded shelter when inclement weather sets in.
Black bears enter a state of torpor in late fall and emerge from their dens by March or April. They survive several months without eating by living off of the enormous amounts of fat reserves their bodies had accumulated over the course of spring, summer and fall eating binges.
Other mammals, such as species of ground squirrels like woodchucks and chipmunks, enter into true hibernation. These mammals' heart rates and body temperatures plummet to such extremes that life itself is barely hanging on. Whereas black bears more or less slumber through the winter, ground squirrels are nearly comatose!
Still, other small mammals such as shrews, moles, pocket gophers, deer mice and voles stay active throughout the winter in underground systems of tunnels, underneath the snow, or inside other forms of natural and man-made shelters. And many of Minnesota's year round resident birds such as black-capped chickadees huddle together inside of cavities or birdhouses to survive winter storms and winter nights, even entering states of torpor that acts to slow their metabolism and helping them survive.
Wintertime is a time of hardship for Minnesota's resident wildlife. Aside from food, fat reserves. and shelter, survival also depends on behavioral and physiological strategies and mechanisms. How they manage with what Mother Nature dishes out is a remarkable testament of wildlife's will to survive as we get out and enjoy the great outdoors.
Blane Klemek is a Minnesota DNR wildlife manager. He can be reached at firstname.lastname@example.org.