The white tailed Ptarmigan is a large flightless bird who is a year round resident of the alpine tundra who experiences the same color change. The ptarmigan has no predators during the cold winter months, yet it changes from brown to a pure white color. Like the weasel, the ptarmigan has no real reason to camouflage in the winter. It’s not as if it’s easy to turn white…hair and feathers are dead cells, so to change color, a bird or mammal must grow an entirely new coat to turn white. Why do both of these animals change color in the winter if they do not need to camouflage themselves?

To answer this question, we need to think of a fluffy down coat and why it is so warm. Down coats are fluffy because there is a lot of air space between the feathers. It is this air space that keeps us warm by trapping our body heat instead of pulling it away from our skin through conduction. The white hairs and feathers are hollow in the center, which causes them to reflect all wavelengths of light, thus appearing white. This hollow structure also increases the airspace in each hair, thus increasing the insulative properties of the winter coat of fur or feathers. Who said going gray doesn’t have its benefits?