The fur of semiaquatic mammals like the mink, otter, muskrat, beaver and others, all possess oils that help them shed water. These oils provide the fur with a natural ability to float better.
The American Mink (Neovison vison) are found throughout Canada and in all but the southwestern portion of America. Their fur provides a wide variety of fly tying opportunities and has been used for years in streamer, nymph, scud and dry fly patterns. My first experience tying with mink was with an old pattern created by Leonard Wright called the, "Fluttering Caddis."