| A | B |
|---|
| preening | the act of grooming and maintaining their feathers |
| molting | the shedding of an exoskeleton, skin, feathers, or hair to be replaced by new parts |
| down feathers | fluffy feathers; help birds stay warm |
| contour feathers | stiff feathers; help birds attract mates and to help them fly |
| lift | upward force on a bird's wings |
| brooding | the act of sitting on eggs and using body heat to keep them warm |
| precocial | active soon after the egg hatches |
| altricial | weak and helpless for a while after hatching |
| air sacs | store air for birds so they have a continuous supply of oxygen |
