[Various bird calls] [Three common tern chicks are huddled together in a shallow nest among rocks. They move around, but stay close together.] [Explore Macaulaylibrary.org]End of transcript
In order to stay warm, many young birds have a special set of fluffy feathers, known as natal down, that function as a coat. These feathers insulate the bird while their parents are out foraging and will eventually be lost and replaced by their adult contour feathers with a layer of down underneath them.