This is not a recipe for
 ice cream. It's a story
 about getting frozen alive!

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Here's the problem for birds: if you don't migrate or hibernate, you need some way to resist the cold. Adding too much fat and feathers could keep you from being able to fly. So most birds in the winter spend much of their time shivering. Have you ever seen a crow sitting on a tree branch in the winter?

Common Raven

Well, it's shivering to keep warm, since shivering basically exercises the muscles and produces heat. (Your body can do the same thing. (See Humans in the Cold.) In fact, for birds like crows and many others, the only time they're not shivering is when they're flying, since flying also uses muscles and produces heat. If a bird was as big as a 165 pound person, on a really cold night it would lose as much 15 pounds overnight from shivering - you'd need to eat 60 hamburgers to get that weight back!

Some birds are better suited to winter than others. Have you ever built a snow hut or fort? Did you notice how the packed snow helps keep the air inside warm? Some birds, including the ruffed grouse, use this exact tactic to survive life below freezing.

Ruffed Grouse

To begin with, grouse are large birds with pretty good insulating feathers. But their coolest adaptation is their ability to dive into the snow. Because the snow insulates the grouse, the air inside can be as much as 25 degrees C warmer than the air outside. Not bad for an apartment without a thermostat!

Finding food in the depths of winter is another specialty of the grouse. Grouse are herbivores, feeding on twigs, buds and catkins of trees. Their gizzards grind up the woody vegetation so they can digest the tough parts of plants. But unlike moose, deer and other mammals looking to forage, grouse have an added advantage: they can fly. Picture a wintertime plant restaurant, served 10 feet up in the air: the moose and deer can't dine there, but the grouse can, and they feast on buds and twigs found over the heads of their competitors.
It may sound like Ruffed Grouse have it easy in a northern winter, but there are still challenges. This is one animal that needs snow-good thick snowbanks to rest in. During years with less snow cover or with crusty snow that's hard to tunnel through, the grouse gets mighty cold.