What prevents birds from hypothermia?

Feathers protect birds from hypothermia. Birds that live in cold climates protect their feathers with fat and their own body so that the inner feathers remain dry to effectively insulate their bodies. Birds fluff their plumage in cold weather to provide air space and keep warm. Birds produce 25-30% more feathers in winter than in summer, just as humans add more clothing for the cold.

Some birds may eat the seeds shortly before dark and slowly digest them for energy throughout the cold night.