Birds

1. Birds Biology 112

2. What are birds? • Reptile-like creatures that have a constant internal temperature • Two legs covered with scales • Front legs have been modified into wings • Covered with feathers • Helps them to fly and keep warm • There are different kinds of feathers

3. Where did birds come from? • Most likely evolved from extinct reptiles however some think they may have come from dinosaurs • Others think that birds and dinosaurs evolved from an earlier common ancestor

4. The Adaptations of Birds They are endotherms (produce their own heat)deriving their heat from a high metabolic rateas well as heat conservation from feathers

5. Digestive System • Eat large amounts of food • Bills are adapted for the type of food they eat • Digestive system: some have a gizzard and a crop • Crop located at end of esophagus where food is stored and moistened • Gizzard is part of stomach where food is ground and crushed into smaller parts

6. Respiration System • System of air sacs and breathing tubes which ensures that air flows into the sacs and out through the lungs in one direction • Lungs are constantly exposed to oxygen-rich air • This helps maintain a high metabolic rate

7. Other Points to Consider • Four chambered heart and double loop system • Excretory system similar to reptiles • Well-developed brain and sense organs • Not all birds fly • Internal fertilization • Lay eggs and keep them warm (nest) • One or both parents may care for offspring