These Animals Don't Care That It's Freezing Outside

Mallard: I have poor circulation, which means my feet are always freezing. I see mallards swimming and waddling around in snow and can't help but wonder how their feet aren't icicles. The answer lies within their unique heat-exchange system, called counter-current circulation. Arteries carrying warm blood from the heart are interwoven with veins carrying cold blood from the feet. The netlike pattern allows blood flowing to the body to be warmed, and blood flowing to the feet to be cooled.