system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do birds that swim in cold water not get frost bite on their feet?

I just drove past a half frozen pond with ducks swimming in it. I understand that feathers provide insulation, but how do birds that swim in cold water not get frost bite on their feet while paddling?
gpt
Birds are warm-blooded animals like humans. Their exposed parts are heated with a constant flow of warm blood from the rest of the body.

Also, the water in a half-frozen pond is at 0 °C which is not cold enough to cause frostbite.