1. Birds: Our Feathery Friends

2. Characteristics Birds are versatile animals There are almost 9,000 living species of birds Some birds live in the tropics while some live in the polar regions. Their diets vary and include meat, fish, insects, fruit, seeds and nectar. Birds have feathers and scales. Also they lay eggs. Birds lay amniotic eggs with hard shells.

3. Characteristics The female birds lay one or more eggs usually in some type of nest. Birds are the only animals who have feathers. A group of eggs is called a clutch. Birds have feathers that help bird's maintain their body temperature and grow. Each feathers grows from a microscopic pit in the skin. When the feather falls out, a new one grows in its place.

4. Anatomy A bird’s circulatory system consists of a heat, arteries, capillaries, and veins. A bird’s heart beats rapidly an active humming bird’s heart can beat more than 1,000 times per minute. When a birds exhales, air with oxygen passes from the air sacs into the lungs. A bird’s respiratory system efficiently obtains oxygen, which is needed to power flight muscles and to convert food into energy. Birds have two lungs. In the birds the food enters the stomach where it is practically digested before it moves into the muscular gizzard.

5. Food and Flight Birds need large amounts of high energy foods to fly. Birds eat nuts, seeds, nectar, insects, and meat. Birds are only animals that have feathers. Birds have feathers that help birds maintain their body temperature and grow. Each feather grows from a microscopic pit in the skin. Its wings move up and down, as well as back and forth. Wings also serve important functions for birds that don’t fly.

6. Other Interesting Facts Birds can be considered pests when their population grows too large. Human uses of birds by hunting for fancy feathers for centuries. A bird has an oil gland that located above the base of its tail. The oil conditions the feathers and helps them last longer.