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 reptiles Feathers 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 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 & Physiological adaptations for flight

Archaeopteryx is defined as the first bird on earth. Archaeopteryx is defined as the first bird on earth. This specimen dates back to the Jurassic, 150 million years ago! This specimen dates back to the Jurassic, 150 million years ago! New specimens of early bird or closely related dinosaur are discovered every year! New specimens of early bird or closely related dinosaur are discovered every year! Archaeopteryx is defined as the first bird on earth. Archaeopteryx is defined as the first bird on earth. This specimen dates back to the Jurassic, 150 million years ago! This specimen dates back to the Jurassic, 150 million years ago! New specimens of early bird or closely related dinosaur are discovered every year! New specimens of early bird or closely related dinosaur are discovered every year! 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 / D 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 n

Four-chambered heart I n t e r n a l T r a n s p o r t I n t e r n a l T 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 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 p r o d u c t i v e 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