Short-tailed weasels are year-round Maine residents, but we tend to call them ermines in the winter when they change from light brown with pale bellies to pure white with black-tipped tails. The unusually bright white quality of their winter fur made ermines especially desirable for the royalty of yesteryear who cherished their skins to create those famous black-spotted bright white fur collars and trim on their red velvet capes.
Episode 055: Ermines
The Nature of Phenology 