system
Given the following post, respond as if you're commenting on Reddit:
human
How do birds keep their feet warm in extremely cold weather?

How do birds keep their feet warm in temperatures in which a human would quickly lose sensation and get frostbitten in? Lets say it's -25 degrees out. A human would quickly lose their ability to control their  bare hands, but birds are perched on trees just chilling. Of course, they have feathers on most of their body, but how do their feet not get damaged by the bitter cold?
gpt
A couple of ways.

Firstly, bird's feet are much more able to function at very low temperatures because there is nothing in them to freeze as it were. Bird's feet are almost entirely comprised of scales, tendons and bone; these tissues are mostly minerals and structural proteins which care little about the temperature, with only few cells for maintenance. All the metabolically active tissues like muscles are up in the body, kept nice and warm.

Secondly birds will, when their feet get cold pull them into their feathers to keep them warm. Many do this all the time when they are flying.

Another important element is bird's feet are relatively dry, due to being scaled rather than covered in skin, so are significantly less effected by the cooling by evaporation that freezes people.