1. EQ: What do birds have in common?

2. What is a bird?
Reptile-like animals that maintains a constant internal body temperature
Outer covering are feathers
2 legs and front limbs modified into wings

3. Feathers Made of mostly protein Develops from pits in the bird’s skin
Help birds fly and keeps them warm
Two types:
Contour (provides the lifting force and balance needed for flight)
Down (trap air close to the body and keeps the bird warm)

4. Evolution of Birds Evolved from extinct reptiles
Most believed they evolved from dinosaurs
Archaeopteryx (birdlike fossil)
Dates back from Jurassic Period (150 million years ago)
Has feathers like a bird, but also has teeth in its beak, a bony tail, and claws on wings

5. Body Temperature Controls
Endotherms- Can generate their own body heat (unlike reptiles)
Average body temperature of birds is 41⁰ C

6. Feeding: Bird Beaks Bird beaks/bills adapt to the type of food it eats
Seed-eaters have short thick beaks
Insect-eaters have short fine beaks
Carnivorous birds have strong hook beaks

7. Feeding: Digestion Birds lack teeth, so they can’t chew food
Crop- food stored here and is moistened
Parent birds will regurgitate food from the crop
After the crop, food goes into the stomach
Carnivore birds have an expandable stomach
Other birds have a gizzard (muscular organ that grinds the food)

8. Respiration Unique and highly efficient system One way flow
Most air first enters air sacs (oxygen in)
then to the lungs (Carbon Dioxide out)
Allows birds to maintain their high metabolic rate (for flying) and temperature

9. Circulation 4 chambered hearts and 2 circulatory loops
Complete separation of oxygen-rich blood and oxygen-poor blood

10. Excretion Similar to reptiles Wastes are removed by the kidneys
Cloaca reabsorbs water, leaving waste in a white pasty form

11. Response Birds’ brains are relatively large for their bodies
Cerebrum is large (controls behaviors such as flying, courtship, nesting, etc)
Well developed eyes
Can see in color (many can see better than humans)
Taste and smell are not as developed

12. Movement Most can fly (those that don’t can run or swim)
Birds’ skeletons are more rigid than reptiles
Strengthened by internal struts
Bones are filled with air spaces, making them lighter
Large chest muscles for flying

13. Reproduction
When ready to mate, sex organs grow larger until functional size
Internal fertilization
Bird eggs are similar to reptiles’ (amniotic eggs)

14. Groups of Birds (an overview)
Nearly 30 different orders of birds
Largest order is the passerines, over 5,000 species which includes finches, crows, sparrows, mockingbirds, and cardinals