Birds

Birds are warm-blooded animals that possess feathers, toothless beaks, and a light skeleton characterized by hollow bones. Most birds also possess feathered wings that typically allow flight, though some species are flightless and are instead better known for running or swimming. In addition, birds lay hard-shelled eggs, which they incubate in a nest with their own body warmth until hatching; the parents then care for the young for an extended period of time until maturation.