Download Birds

Birds
Ch. 31.2
What is a Bird?
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Reptile-like
Maintain a constant internal body temp
Out covering of feathers
2 legs with scales
Front limbs modified into wings
• Feathers are the most important
characteristic that separates from
reptiles
– Made of proteins
– Help with flight and warmth
• 2 main types of feathers
– Contour
– Down
Evolution of Birds
• Many paleontologists believe birds are
dinosaurs with feathers
– Fossils found in the late Jurassic Period
– Looked like a small running dinosaur
with feathers
– Had teeth, bony tail, and toes/claws on
wings
• Debate as to whether they evolved
FROM dinosaurs or it they evolved
WITH dinosaurs
• Modern day evidence shows that
they’re closely related
Form, Function, and Flight
• Highly efficient digestive, respiratory,
and circulatory systems
• Aerodynamic feathers and wings
• Strong chest muscles
Body Temperature Control
• Generate their own heat
• Endothermic; high rate of metabolism
(produces heat)
• Feathers provide insulation
Feeding
• More a bird eats, the more energy is
generated
• Beaks/bills are adapted to the type of
food they eat
• No teeth; can not break down food by
chewing
• Have a CROP – food is moistened and
stored before it moves down the
digestive track
• GIZZARD – helps break down food
by grinding
• Waste released to the CLOACA
• Respiration: use AIR SACS to for gas
exchange
• One way air flow
– Helps maintain metabolic rate
• Circulation: 4 chambered heart and 2
separate circulatory loops
• 2 separate chambers (oxygen rich and
oxygen poor chambers)
• Excretion: nitrogenous wastes are
removed from the blood by the
kidneys, converted to uric acid,
deposited in the cloaca
• Response: large brain contributes to
behaviors such as flying, nesting,
courtship, parenting, precise
movements
• Well developed eyes, can see color
• Good hearing
• Movement: bones may be fused
together; rigid skeleton
• Hollow bones large chest muscles
helpful for flight
• Reproduction: reproductive tracts
open to the cloaca
– Amniotic eggs that are incubated until
born
Groups of Birds
• ~30 different orders
• Very diverse animal
– Pelicans – aquatic
– Parrots – colorful and noisy
– Birds of prey – raptors, hunt prey
– Cavity nesting birds – live in holes
– Perching – largest order
– Herons – aquatic waders
– Ostriches – runners and swimmers
Ecology of Birds
• Pollination
• Migration of long distances
• Indicators of environmental factors