Sources : Ermine

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Quadrupeds 4.40): They say that the ermine is a small animal of the genus weasel, but in shape it is smaller and the color is different. In the winter season it glows like snow, except at the tip of the tail. In summer, however, the belly only glows, but the back appears brown. It chases mice; it feeds on meat. The skins of these animals are of great interest to men, and are usually used in clothing. - [Badke translation/paraphrase]