Ever wonder why a bird’s feet don’t freeze in the winter time? It’s not like they’re exactly well-insulated. Bird feet are mostly sinew, bone, skin, and not much else—meaning there’s not a whole lot there that needs to be kept warm, so very little blood flows into the feet in the first place.
A fine network of interlaced veins and arteries helps protect their feet from freezing in sub-zero temperatures in the winter. The chilled blood is carried from the feet and goes through the veins and adjoining arteries. This process warms the blood before it even reaches the heart and go back out to the body again. This helps keep the feet just warm enough so as not to freeze, and very little heat is lost.
So why don’t their little feet freeze to the metal, ice, and snow-covered perches they sit on? Answer: Bird feet have no sweat glands, so they don’t create any moisture and there is no danger of feet freezing to a perch!
Photo credit: Hanging In There, Norma Larabee Gabriel