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Birds

VIEWS: 8 PAGES: 37

  • pg 1
									   Birds

Chapter 21
    Birds
 Evolutionary     perspective
  –Phylogenetic Relationship
    • Class Aves - means bird
      –Flight
         » Wings
         » Feathers
         » Endothermy
         » Modified vertebral column
         » Light bones
         » High metabolic rate
      –Bill replaces teeth
Birds
  Descended   from
  Archosaurs
  –Crocodile and
   dinosaurs
    • Wish bone
      present
    • Feathers present
Birds
     Shared
      characteristics
      – Occipital condyle
      – Ear structure
      – Lower jaw structure
      – Nucleated RBC’s
      – Kidney and liver
        function
      – Some behavioral
        characteristics
Birds
   Ancient birds
   and flight
    –Ancient birds
      • Sinosauropteryx,
        Protarchaeopteryx,
        and Caudipteryx
      • Turkey sized birds
      • None fliers
                Birds
   Archaeopteryx
    – Oldest bird
      discovered
    – Evolution
      between birds
      and reptiles
   Ganus
    yumenesis
Birds
    –Diversity of
     modern birds
        • 9,100
          species
        • 27 Orders
        • 160 mya - 70
          mya
Birds
 Evolutionary
 pressures
  –External structures
   and locomotion
    • Adaptation to flight
    • Plumage - feathers
      on a bird
      –Provide lift for flight
      –Insulation
Birds
 – Feathers
   • Contour Feathers
     –Flying feathers
       » Vane and outer/inner
         webs and shaft
       » Feather barbs
   • Down Feathers
     –Insulating feathers
   • Filoplume Feathers
     –Sensory functions
Birds - Rubbing
 • Preening
   the bill over its
   feathers
 • Anting - Many
   songbirds rub ants on
   their feathers
 • Molting - Replacing
   dead or worn-out
   feathers
 • Colors vary
Birds
Birds
 –Skeleton
  • Perforated
    –Lightweight
    –Strong
    –Internal Struts
    –Reduced number of
     skull bones
    –Dense bones in
     aquatic birds
Birds
  • Ribs – thoracic region
    – Posteriorly directed
      uncinate process
  • Synsacrum – lumbar
    region
    – Maintain proper posture
  • Pygostyle – posterior
    caudal region
    – Supports tail feathers
      for steering
Birds
  • Single occipital
    condyle
     – High degree of head
       rotation
  • Keel
     – Attachment of flight
       muscles
  • Furcula
     – Wishbone attaches to
       flight muscles
  • Perching tendons
     – Help grip foot
Birds
  –Muscle
   • Largest muscles
     are the flight
     muscles
     –Multiple
      mitochondria
     –Produce lots of
      ATP
Birds
 Flight
  – Airfoil
    • Air on top passes
      over faster,
      decreasing pressure
      on top
    • Lift has to be
      stronger than weight
    • Force forward has to
      be stronger than drag
Birdsof attack
– Angle
  • Decreased angle
    decreases turbulence
– Alula
  • Group of small feathers
    in front
– Powerstroke
  • Down stroke
  • Distal part of the wing
    generates the most
    force
– Upstroke
  • Recovery stroke
Birds
 – Gliding
   • Ducks
 – Flapping
   • Most common
 – Soaring
   • Vulture
 – Hovering
   • Hummingbird
   • 50 to 80 beats per
     second
Birds
–Nutrition
  • High metabolic rate
    –Endothermic
    –Flight
  • Torpid at night
    –Reduced body
     temperature
    –Reduced respiration
Birds
 • Bills and tongues are
   modified
   –Feeding
   –Preening
   –Nest building
   –Courtship displays
   –Defense
Birds
• Crop
  – Storage structure of the
    esophagus
  – Pigeon’s Milk
• Gizzard
  – Grind food
  – Swallow sand
Birds
–Circulation
  • Heart
    –Similar to reptiles
    –Completely separate
     atrium and ventricles
    –Sinus venosus -
     pacemaker
    –2.4 % of total body
     weight
      » 1,000 beats/minute
   Birds
–Gas exchange
 • Complex and efficient
   –Cycle 1 of 2
      » External nares bring in oxygen
        into trachea
      » Trachea contains the voice box
        or syrinx
      » Oxygen is then taken to the
        abdominal air sacs
      » Air already in the lungs moves
        through the parabronchii to
        the thoracic air sacs
Birds
–Cycle 2 of 2
  » From the air sacs of the lungs,
    the air moves to the thoracic
    sacs
  » Thoracic sacs expel air out
    of trachea with help from the
    movement of sternum and
    ribs
  » Birds have a greater rate of
    oxygen consumption than any
    other vertebrate
 Birds
–Thermoregulation
  • Body temperature
    between 38 and 45oC
    –Extremes are 32 to 45oC
    –Birds fluff feathers to stay
     warm
    –Some birds become
     torpid at night
    –Flying increase internal
     heat
     Birds
   Nervous and sensory
    – Forebrain is much larger
      • Cerebral hemisphere
         – Corpus striatum – visual
           learning and feeding
      • Smell is sophisticated in
        turkeys and vultures
      • Hearing is well developed
        for almost all birds
      • Vision is important for most
        birds
Birds
• Eyes are much larger than
  in other vertebrates
  – Double focusing
  – Rods – low light intensity
  – Cones – high light intensity
     » 1,000,000/mm2
     » Search fovea – wide angle
       of view
     » Pursuit fovea – binocular
       vision
  – Nictitating membrane
Birds
         and
 Excretion
 osmoregulation
  –Same demands as
   reptiles
  –Uric acid is
   produced
  –Salt gland – drain
   sodium chloride
   out of nose
Birds
   Reproduction
    – Oviparous
    – Males
      • Most birds have no
        intromittent organ
      • Two testes that enlarge
        during mating season
        – Seminal vessicle –
          sperm storage
Birds
–Females
  • Two ovaries form
    during development
  • Left ovary usually
    develops eggs
  • Shell is developed at
    the lower region of
    the oviduct
Birds
 –Territory
   • Mating occurs
     within a given area
   • Defense is key
   • Monogamous
     relationships occur
     –During breeding
      season
     –For life – Swans,
      geese, and eagles
Birds
  • Polygynous
    –Male mates with
     more than one
     female, female
     cares for nest
  • Polyandrous
    –Female mates with
     more than one
     male
Birds
– Nesting
  • Species specific
  • Clutch – group of eggs
    laid and the chicks
    produced
  • Brood patch keeps eggs
    warm
  • Parents turn eggs
    preventing deformation
  • Incubation period last 10
    to 80 days
Birds
 • Altrical – birds that are
   entirely dependent of
   parents
    – Ex. Robin
 • Precocial – young
   need parent to lead
   them but can run, swim,
   and feed
 • Mortality – 1 year
 • Captivity – 10 – 20
   years
Birds
 Migration
  – Periodic round
   trips between
   breeding and
   nonbreeding sites
    • More pronounced
      in Northern
      hemisphere
    • Photoperiodism
Birds
   Navigation
    –Route-based
     navigation
    –Location-
     based
     navigation

								
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