Why don't birds legs freeze?

I live in an area where the winter can and does get to -40 and there is the odd time that daytime temps dont get above -20c for a couple weeks on end. Yet, you see birds with their skinny little exposed legs standing around all the time, totally exposed to the elements. Why doen’t the just get real bad frostbite and the flesh eventually die and fall off like any other animal/mammal would? (people included)

I asked this question a while back here.

Swimming waterfowl? At this time of year? Brrr…

      • And in the spirit of providing useless information, researchers have found that only half a duck’s brain ever goes to sleep at any one time. They keep one eye always open, and in a flock, arrange themselves so that the preimeter ducks have their open eye facing outwards, to watch for predators. The half of the brain that serves the concerned eye stays awake while the other half sleeps. Every hour or two they turn (if in a group) and switch eyes. Even lone ducks will do it though; I suppose half coverage is better than none. - MC