Our ducks seem to be much more cold tolerant than our chickens. It helps that they're a little fat! We had water in the pools down to 34 degrees out (because we don't want the expanding ice to break the plastic pools when it freezes) and they were swimming in those pools up until then without a problem... now, our ducks 'hate' wind, so they hide out in the woods behind or next to - depending on the wind direction - a fallen log. Fortunately we've had no cases of frostbite in the few years we've had ducks, although the chickens are getting it already and it hasn't even dropped below 20. :/