And so, winter arrives in Montana
Just found out a friend is fishing in the Bahamas.
The Bahamas.
The rest of us cope with winter, shoveling snow, adjusting the thermostat.
And that’s not too different from the natural world: Some birds migrate, some stay here; some mammals hibernate, some stay awake.
But all creatures big and small have survival strategies.
The ultimate survival trick for birds is to migrate, if not the Bahamas, then the southern U.S. or south of the border. Migration is not without its hazards, but the reward is a warm winter in the sun.
For mammals, there is hibernation, though that too can be hazardous as winter starvation is always a threat. The reward, however, is sleeping through the worst of the cold.
But mammals and birds that stay here and stay awake are ready for winter now. They have feathered up, bulked up or slowed down their metabolism for the coming season.
Bigger problems may arise if the winter drags on into spring. Then a quirk of weather or bad choice can be fatal.
For now, subzero temperatures and a foot or two of snow are not so bad for, say, elk or ducks and geese.
Waterfowl, like geese and ducks, will stand or sit for hours on an ice shelf next to a river’s open water. They survive by wearing a nice, plump down coat. Their exposed feet have adapted, too.
First, their legs and feet have very little muscular, or soft, tissue that needs blood to keep warm. The few muscles that operate the foot are mostly higher up in the feather covered leg and connected to the bones of the feet with long tendons.
Second, warm blood flowing through the birds’ arteries passes close to cold venous blood returning from the feet. As arterial blood warms up the venous blood the few tissues in the feet receive just enough warmth to avoid frostbite.
Of course all birds have feathers that create air pockets between the feathers and the skin that help contain heat.
Some birds use other tricks, like clustering together. Grouse will bury themselves in snow. Other birds will roost in tree cavities or dense foliage or brush piles to cut both the wind and heat loss.
Depending on the species, some birds can even shiver specific muscles to increase metabolism and generate extra heat.
Mammals, like elk, have thick fur coats we can wish for.
An elk’s winter coat has two layers: a dense, woolly undercoat covered with thick, long guard hairs.
Each guard hair contains tiny air pockets that make it waterproof and provide insulation. In very cold weather, snow on the thick guard hair coat often doesn’t even melt because the animal’s body heat is held in by the undercoat. Also, elk can make their hair stand on end, creating a thicker coat that traps more air.
As a final trick, when bitter cold becomes a major problem for elk, they will either gather in tight groups on windswept areas to take advantage of warmth and safety in numbers, or move into conifers, seeking insulation.
Of course if the weather changes and gives us a warm sunny day, elk cannot just unzip their coats. To avoid overheating, the animals may hunker down during the day in timber on north-facing slopes.
Whatever their method, wildlife that spend the winter in Montana are ready now.
Bruce Auchly
FWP Region 4 Information Officer