A quick dip
Dippers plunge right into streams to feed. American dippers live in Yellowstone National Park and feed in the hot springs which stay free of ice even in winter. A dipper's thick, oily plumage retains air which forms a silver cloak over the surface of its body. This keeps it warm underwater, but also makes it buoyant, so dippers have to work hard to stay submerged. They seldom manage to stay underwater for more than a quarter of a minute at a time.