Animals That Turn White in Winter

As temperatures drop and autumn gives way to the seemingly ceaseless snows of winter, some animals in northerly climes exchange their pelage or plumage of summer drab for the purest white. Unlike many white animals associated with the north, such as polar bears and snowy owls, which are white all year, these creatures shift their colors with the seasons. Why this happens is not entirely clear. While camouflage is one evolutionary factor that has selected for seasonally white fur, it is likely that the switch to winter whites confers other advantages as well. Scientists believe that if staying hidden were the only upside, many more snow dwellers would be white, but that is not the case. In fact, most Arctic animals do not change color with the seasons at all, even species closely related to those that do. One theory is that a pale coat may have better insulating properties—because melanin, the substance responsible for colored hair, is absent from white fur, leaving air spaces in the hair shaft.