BirdNote is a new weekly feature on VPR.  We'll learn about birds from around the world and hear their songs.  Listen at 8:57 on Saturday mornings.

Have you ever watched ducks walking around in freezing temperatures and wondered why their feet don’t freeze? And how do birds, including the pictured Northern Flicker, sit on metal perches with no problem?

Birds’ feet have a miraculous adaptation that keeps them from freezing. Rete mirabile — Latin for "wonderful net" — is a fine, netlike pattern of arteries that interweaves warm blood from a bird’s heart with the veins carrying cold blood from its feet and legs.