February 22 Ducks Say Still Winter

A group of mallards (Anas platyrhynchos) has been living on the Yahara River for most of this winter, swimming back and forth to stay in open water. 30 were hunkered down on the ice today, and while a few noticed me, stretched, and cleaned their wing feathers as if readying to move, they realized it was too cold and tucked their heads back in. This posture is the same as if we lay down underneath a down blanket. In extreme cold (today's wind chill was -15 F), waterfowl will tuck their legs in underneath and bill and head into their feathers. The feathers aren't warm: they zip together to create airspace between the duck's fat layer and the sealed feathers, which traps body heat. So their insulation depends on air. The Internet tells me humans have known about feather warmth forever, but we've only worn those hip down vests and jackets since the 1940s. If our feather-filled sleeping bags or coats get soaked, they no longer proved any warmth since the airspace is flattened. Ducks, though, can dry their feathers in seconds by flapping their wings. This is why they can take naps on their ice beds in -15 degree winds. I am impressed.