December 16, 2014

Built for Winter

When it’s cold out people can put on a coat, snow pants, hat, gloves, and scarf. We have skis and snowshoes to help us move on the snow. When we come inside we turn up the heat or light a fire. Humans have found ways to overcome our weaknesses in relation to winter weather. But animals that remain active in the winter must find ways to survive the changing landscape.

One of these animals is the ruffed grouse (Bonasa umbellus). They are built for survival. Their feathers are mottled browns and white that helps them to blend with their surroundings during any season. This coloration mimics the shadowing effect on the forest floor of light coming through branches where ruffed grouse eat food from crabapple trees (Malus species) or aspens. Grouse usually remain still as you pass by until the final instant, when they suddenly fly away, startling you as you enjoy a stroll.

In winter, ruffed grouse are protected from the cold by their feathers. Feathers are very effective insulators. The legs of grouse are partially covered with feathers and feathers also extend out past their nostrils so they breathe in warmed air. Ruffed grouse will often spend an evening or cold day under low-hanging branches of coniferous trees for added warmth. When snow is deep (10 inches or more) they will even make snow caves by diving into the snow. The added insulation of snow can keep the temperatures near 0 degrees Celsius even during extreme cold conditions.

Being rather bulky birds that spend much of their time on the ground, walking in deeper snow may pose some problems. The grouse has evolved to combat this problem by growing pectines, or comb-like structures, around their toes, which act as snowshoes.

Even though ruffed grouse are fairly large birds, they do not store much fat on their body. Hanging out in trees can be a dangerous activity with no leaves to keep you hidden and safe from predators. Ruffed grouse will eat very quickly, stuffing their crops with enough food to survive a day in less than 25 minutes. This, combined with the energy-saving physical and behavioral adaptations, make the ruffed grouse built for winter.

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