Zoology Notes: BIRDS

What is a bird?

• Basic Definition:– warm blooded vertebrates – feathers– two legs for walking/perching– front limbs modified into wings

Birds, ARE reptilesFeathers and endothermy (warm blooded-ness) are

the main character traits that separates birds from other reptiles

3 F e a t h e r T y p e s3 F e a t h e r T y p e s3 F e a t h e r T y p e s3 F e a t h e r T y p e s• Contour feathers: shape and

maneuvering– Flight feathers:

lift and balance; asymmetrical– General body feathers: often

bright colors, symmetrical.

• Down feathers: soft & fluffy to provide insulation

• Powder feathers: Release a fine white powder that prevents water from penetrating the down feathers – Water birds also have special oil

glands to repel water

• Assymetrical Feathers• Light, “hollow” bones• Respiratory system: air sacs

extended from the lungs into the body cavity

• Digestive System: no urinary bladder

• High metabolism rate

Structural & Structural & Physiological Physiological

adaptations for flightadaptations for flight

Structural & Structural & Physiological Physiological

adaptations for flightadaptations for flight

• Archaeopteryx is Archaeopteryx is defined as the first defined as the first bird on earth. bird on earth.

• This specimen dates This specimen dates back to the Jurassic, back to the Jurassic, 150 million years ago!150 million years ago!

• New specimens of New specimens of early bird or closely early bird or closely related dinosaur are related dinosaur are discovered every year!discovered every year!

• Archaeopteryx is Archaeopteryx is defined as the first defined as the first bird on earth. bird on earth.

• This specimen dates This specimen dates back to the Jurassic, back to the Jurassic, 150 million years ago!150 million years ago!

• New specimens of New specimens of early bird or closely early bird or closely related dinosaur are related dinosaur are discovered every year!discovered every year!

A r c h a e o p t e r y x A r c h a e o p t e r y x

A r c h a e o p t e r y x A r c h a e o p t e r y x

• Birds have high metabolic rates and burn calories to keep warm (endothermic!).

• Crop: enlarged area in the esophagus, where food can be stored and moistened before it enters the stomach. Sometimes stored food is regurgitated to feed young.

• Gizzard: Muscular part of the stomach that contains gravel swallowed by the bird. This then “chews” food, which makes it easier to digest.

F e e d i n g /F e e d i n g /D i g e s t i o nD i g e s t i o nF e e d i n g /F e e d i n g /

D i g e s t i o nD i g e s t i o n

• Air Sacs: enable birds to remove oxygen from the air when they inhale AND when they exhale – VERY efficient respiration! – Air sacs are also found in

some dinosaurs! – Can affect buoyancy in birds

with aquatic ecology.

R e s p i r a t i o nR e s p i r a t i o nR e s p i r a t i o nR e s p i r a t i o n

• Four-chambered heart

I n t e r n a l I n t e r n a l T r a n s p o r tT r a n s p o r tI n t e r n a l I n t e r n a l

T r a n s p o r tT r a n s p o r t

• Urine (uric acid) flows to cloaca where all the water is absorbed leaving uric acid crystals (paste like “bird droppings”)

• Some birds have specialized salt excreting glands near their eyes to eliminate excess salt

E X C R E T I O NE X C R E T I O NE X C R E T I O NE X C R E T I O N

• Well developed eyes - see color very well; see more shades of colors

• Sense of taste and smell not as well developed (with some exception – vultures!)

• Some have acute sense of hearing• Magnetic sense - birds use magnetic poles to navigate

long migration routes.

R e s p o n s e R e s p o n s e R e s p o n s e R e s p o n s e

R e p r o d u c t i v e R e p r o d u c t i v e S t r a t e g y S t r a t e g y

R e p r o d u c t i v e R e p r o d u c t i v e S t r a t e g y S t r a t e g y

Two primary strategies:•A l t r i c i a l - helpless at birth or hatching and require parental care for some time•P r e c o c i a l - able to move about and care for themselves to a considerable extent immediately following birth or hatching