Birds Biology 112

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

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

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

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

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

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