Chapter 21Birds

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Chapter 21-Birds
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Class Aves- Birds

• 8,700 species
• Forelimbs modified into wings
• Amniotic eggs (hard-shelled)
• Scaled feet and legs
• Strong, light-weight skeleton
• Endothermic metabolism (104 F to 108 F)
• Completely divided ventricle
• Oxygenated and deoxygenated blood completely
  separate
• Highly efficient lungs
• Syrinx- Birds song box

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Bird Heart
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Highly Efficient Lungs

• One-way air flow
• Air sacs store gas (more efficient)
• Lungs exposed to only oxygenated air
• Blood travels in opposite direction

• Endothermic metabolism, completely divided
  ventricle, and efficient lungs account for energy
  needed for flight

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Highly Efficient Lungs
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Bird Skeleton

• Thin
• Hollow
• Many bones fused for sturdy muscle attachment
• Keel- Enlarged breastbone and fused collar bone
• Breast muscles attachment (30 of weight)

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Class Aves- Birds

• Brain to body size ratio second only to mammals
• Digestion
• Beak lacks teeth
• Crop- Expanded portion of esophagus stores food
• 2-chamber stomach
• Proventriculus - 1st Digestive acids partially
  break down food
• Gizzard- 2nd Muscular grinds and crushes
• Waste exits cloaca
• Covert nitrogenous wastes to uric acid in a
  harmless white paste form

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Feathers
Camouflage

• Covered in feathers (modified reptilian scales)
• Develop from follicles (tiny pits in skin)
• Molt feathers individually
• Also function as camouflage or attracting mates
• Sexual dimorphism- Males and females have
  different appearances
• Males more brightly colored to attract females

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Feathers Attract Mates
Male and female cardinals
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Feathers

• Follicles- Small sacs in skin where feathers
  develop
• Two types
• Contour feathers- Cover body and give shape
• Flight feathers- wings and tail
• Protect and streamline
• Rachis- Broad, flat part of feather
• Vane- central shaft of feather
• Branches (barbs) w/barbules (projections with
  hooks) interlock
• Quill- bottom section of rachis (calamus)
• Preening- Pulling feathers to relink connections
• Preen gland- Secretes oil to clean and waterproof
  feathers
• At base of tail
• Down feathers- Insulate under contour feathers

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Bird Feathers
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Amazing Bird Flights
Hummingbird

• Hummingbirds flap their wings rapidly (20-80
  beats per second)
• Smallest birds
• Migrating birds can travel up to 2,000 miles in 6
  days
• Gulls and vultures use upward air movement to use
  little energy

Turkey Vulture
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Bird Reproduction and Offspring

• Monogamous- many bird species have mating pairs
  and mate for life
• Clutch- a group of eggs in a nest
• Incubate- Male or female parents keep eggs warm
• Albumin- Egg white (protein)
• Altricial- birds helpless at birth
• Few eggs at a time
• Stay in nest a long time
• Ex songbirds (i.e. American Robin)
• Precocial- birds well developed at birth
• Large numbers of eggs
• Feed themselves
• Ex Ducks and chickens

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Bird Diversity

• 28 orders (see page 329)
• 60 order Passiformes (song birds)
• 5,300 species largest group of terrestrial
  vertebrates

Robin
Mocking bird
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Bird Adaptations

• Adaptations based on habits and diet
• Beak (bill)
• Legs
• Feet
• Some adaptations include
• Stream-lined bodies for flying over water
• Low-light vision for feeding at night (nocturnal)
• Wings adapted for swimming

Sea gull
Barn owl
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Flightless Birds

• Ostriches (Africa) Emus (Domesticated)
• Largest birds
• Body to heavy for flight
• Penguins (Antarctica)
• Adapted wings for swimming

Emperor penguin family
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Avian Adaptations
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Avian Adaptations
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