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Birds Class: Aves

Birds Class: Aves. Characteristics. Well adapted to marine, freshwater, & terrestrial habitats Bodies adapted for flight Endothermic - body temperature controlled by metabolism ( 40 to 41 degrees Celsius body temperature) ). Evolution. Evolved from reptiles

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Birds Class: Aves

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  1. BirdsClass: Aves

  2. Characteristics • Well adapted to marine, freshwater, & terrestrial habitats • Bodies adapted for flight • Endothermic - body temperature controlled by metabolism (40 to 41 degrees Celsius body temperature) )

  3. Evolution • Evolved from reptiles • Few fossils due to lack of preservation of feathers or thin, hollow bones

  4. Characteristics of Birds • Body covered with feathers made of protein called keratin • Thin, hollow bones • Some bones fused for extra strength • Forelimbs modified into wings for  flight • Two hind limbs with claws to support upright body • Scales on legs

  5. Toothless, horny beak • Additional air sacs  with lungs for more oxygen

  6. Amniote egg with calcium carbonate shell • Oviparity with both parents often caring for eggs • Eggs usually incubated within a nest

  7. Feathers!!!

  8. Feathers: • Modified scales • Function to provide lift for flight & help conserve body heat • Five kinds of feathers ----- down, contour, flight, filoplume, & bristles

  9. Down feathers: 1. Soft & fluffy2. Cover the body of nestlings3. Provide an undercoat insulating adult birds

  10. Down feathers

  11. Contour Feathers: 1. Give streamline shape to body2. Provide coloration to adult birds3. Give additional insulation to body

  12. Contour

  13. Flight Feathers: 1. Specialized contour feathers2. Found on wings & tail

  14. Flight feathers

  15. Filoplumes: • 1. Called pin feathers2. Hair like feathers under contour feathers on body

  16. Filoplumes

  17. Parts of a feather • Develop from tiny pits in the skin called follicles • Shaft emerges from the follicle • Two vanes develop on either side of shaft • Barbs branch off of each vane & have projections called barbules • Barbules have microscopic hooks to hold barbules together

  18. Parts of a Flight Feather

  19. Microscopic Hooks on Barbules

  20. Feathers • Birds preen their feathers to clean them & coat them with oil • Preen glands - oil glands located at the base of the tail • Birds shed or molt feathers periodically:1. Molting usually in late summer between breeding & migration2. Flight feathers replaced3. Some birds molt before courtship

  21. Beaks and Feet • Adapted to habitat & feeding • Hawks & eagles have hooked beaks & talons for tearing meat

  22. Swifts have tiny beaks that open wide to catch insects in midair • Flightless birds like ostriches have legs & feet modified for running & walking

  23. Penguins have wings modified into flippers for swimming • Ducks & geese with webbed feet

  24. Legs of some birds such as herons &  egrets turn vivid colors to attract mates

  25. Muscles • Flight muscles called pectorals & are attached to wing & keeled sternum • When large pectorals contract, wings move down • When large pectorals relax & small pectorals contract, wings move upward

  26. Body Temperature • Metabolism generates body heat (endothermic) • Enables birds to survive in warm & cold environments • Rapid breathing & increased air sacs in lungs bring in more oxygen

  27. Ingest large amounts of food for energy • Fluff out feathers to trap air for insulation • Aquatic birds have thin layer of fat for insulation

  28. Digestive System • Fast & efficient digestion • No chewing • Crop for temporary food storage • Two part stomach --- proventriculus & gizzard • Proventriculus is 1st chamber where digestive juices added • Gizzard is 2nd part for crushing food

  29. Pyloric sphincter valve at lower end of gizzard controls food movement into intestines • Duodenum - beginning of small intestine where bile (digests fats) & pancreatic juice are added & digested food is absorbed

  30. Respiration • Fly at high altitudes where there is less oxygen so need efficient respiratory system • High metabolic rate requires large amount of oxygen • Nine air sacs associated with lungs increase oxygen level & decrease density

  31. Air pathway:air enters body through nostrils on beak  trachea (windpipe) syrinx (voice box) 2 primary bronchi 75% of air into two posterior air sacs and 25% of air into lungs air from lungs into other seven air sacs

  32. Circulatory system • Four chambered heart • Right side of heart pumps deoxygenated blood from body cells to lungs • Left side of heart receives oxygenated blood from lungs & pumps it to the body cells • Single aortic arch • Rapid heartbeat (hummingbird 600X/minute & chickadee 1000X/minute) • Less active birds such as ostrich have slower heart rates (70X/minute)

  33. Nervous System • Large brains relative to size of bird • Cerebellum coordinates movement • Cerebrum controls navigation, mating, nest building, & care of young • Optic lobes receive & interpret visual stimuli • Have color vision for locating food

  34. Reproductive System: • Testes in males produces sperm that travels by the vas deferens to cloaca • Females have single ovary that makes eggs • Eggs are fertilized in the oviducts • In mating, male presses cloaca to female to transfer sperm (internal fertilization)

  35. amnioteegg • 1. Embryo suspended in fluid called albumen (white of egg)2. Chalaza - rope like strands suspending embryo in albumen3. Chorion is membrane inside of shell4. Yolk is stored food surrounded by yolk sac

  36. Eggs incubated by one or both parents  • Brood patch - thickened, featherless patch of skin on abdomen of bird used to warm eggs

  37. Yolk sac has blood vessels to carry food to embryo •  Wastes from embryo collect in membrane called allantois • Chorion membrane lines the shell & allows gas exchange

  38. Young birds may be precocial or altricial Precocial young: Altricial young: 1.Lay fewer eggs2. Hatch quickly3. Hatchlings are blind, naked, & helpless4. Depend on parents for warmth & food for several weeks5. Includes songbirds, woodpeckers, hawks, pigeons, doves, raptors • 1. Have longer incubations2. More eggs laid3. Active as soon as hatch4. Nestlings can swim, walk, & feed themselves5. Need some parental care6. Includes ducks, geese, & swans

  39. Behavior: • Longer parental care allows more complex learning (courtship, nesting, migration, etc.) • Territoriality allows males to establish & defend breeding areas

  40. Courtship • behaviors used by males to attract mates:1. Brightly colored feathers2. Flight displays3. Songs

  41. Courtship

  42. Nest building holds eggs, conceals & shelters young birds, may help attract mates • Nests are built in sheltered, well-hidden spots in trees, on the ground, etc. & are made of twigs, mud, grass, feathers...

  43. nests

  44. Migration • triggered by dropping temperatures & dwindling food supplies • Birds use migration clues including:1. Position of sun & stars2. Topographical landmarks3. Magnetic clues4.Air pressure changes5. Low frequency sounds

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