#AmericanRobin ( #Turdusmigratirius ) All fluffed to to keep warm “The down feathers trap the air, an excellent insulator. Puffed out feathers insulate the birds internal organs so that they stay at 104° F. The outside of the feather is cold, just like the air. But, just a few millimeters under the feathers, the birds body temperature is a cozy 104° F. Multiple layers of feathers are the worlds best insulator”. – journeynorth.org The above site tracks migration.