Birds

3. Movement of birds from winter and summer homes.
6. Birds lay _______ eggs that are protected by a shell.
11. Birds have many importance, including eating them as a food source and they ______ crops.
12. This body part stores the food.
13. Birds have a ____-chambered heart.
15. This type of feather covers the body and helps them with flying.
16. The smallest bird in size is the _______.
18. These are attached to the muscles to help birds fly.
19. Birds have ______ bones which keep them light to fly.

1. Birds use a lot of _____ when flying so they need to eat often.
2. This body part grinds the food.
4. After birds lay their eggs, they _______ them until they are born.
5. Birds are ______-blooded animals.
7. Birds take in _____ when they inhale and exhale which provides lots of energy for flying.
8. Not all birds can _______.
9. This type of feather is soft and keeps them warm.
10. At high altitudes, birds can _____ rather than flap their wings.
11. This process helps to waterproof the feathers by rubbing oil on them.
14. Birds live ______! Polar, tropics, desert, and water.
17. Birds have this type of symmetry.