Feathers act as insulation, they are warm blooded, and opportunistic eater. My chickens are hardy to -20 degrees outside. So long as they were farther south I

Feathers act as insulation, they are warm blooded, and opportunistic eater. My chickens are hardy to -20 degrees outside. So long as they were farther south I could imagine them surviving. Even if they were north, as long as they could eat meat, the coming cold temperatures could keep food (other dead animal) around for quite a while. Even then, I could image ancestors of vultures doing quite well for a good long while. Anyway, also a naive set of guesses on my part.