| A | B |
|---|
| Feathers | Made of keratin, used for flight, and help prevent heat loss. |
| Wings | a bird's forelimbs. |
| Beak | A tough honry sheath that covers the jaws. |
| Furcula | Fused collarbones. |
| Down feathers | Soft, fluffy feathers that cover the body of nestling birds and provide an insulating undercoat in adults. |
| Contour feathers | Give adult bird their streamlined shape and provide coloration and additional insulation. |
| Flight feathers | Specialized contour feathers on the wings and tail. |
| Follicles | Pits in the skin where feathers develop. |
| Shaft | Emerges from the follicle and is the central part of a feather. |
| Vanes | A side of a feather. There are usually two of them. |
| Barbs | Branches that come from the vane. |
| Barbules | They give the feather its sturdy but flexible shape. |
| Sternum | Breastbone |
| Pygostyle | The terminal fused vertebrae of the spine. |
| Proventriculus | The first chamber of the stomach where food begins to break down. |
| Gizzard | The muscular part fo the stomach where food is kneaded and crushed. |
| Vasa deferentia | Small tubes that sperm travel through before entering the cloaca. |
| Oviduct | A long funnel shaped chamber where eggs are released from the ovaries and wait to meet with the sperm. |
| Brood patch | A thickend featherless patch of skin used to incubate the eggs until they hatch. |
| Precocial | Birds that are active as soon as they hatch. Ex. ducks. |
| Altricial | Birds that are blind, naked, and helpless when they hatch. |
| Ornithologists | Biologists who study birds. |
| Syrinx | A structure found in the base of the trachea in song birds used to warn other males and attract females. |
| Crop milk | Milk produced by pigeons and doves used to feed their young. |
