Birds

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Birds

• Chapter 42

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Origin and Evolution of Birds

• Section 42.1

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Important characteristics

• Feathers only birds have them!
• Wings modified forelimbs
• Lightweight, rigid skeleton hollow bones
• Endothermic metabolism 104-106o F
• Unique respiratory system most efficient
• Beak no teeth
• Oviparity eggs incubated by parents

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Evolution

• Similarities to dinosaurs
• Flexible, S-shaped neck
• Unique ankle joint
• Hollow bones
• Birds evolved from small, fast-running
  carnivorous dinosaurs
• Oldest bird fossil - Archaeopteryx

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Archaeopteryx

• Jurassic period 150 million years ago
• Similar to modern birds because
• Hollow bones
• Furcula fused collarbone (aka wishbone)
• Feathers
• Similar to dinosaurs because
• Teeth
• Claws on forelimb
• Long, boney tail

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Origin of flight
Video

• Two major hypotheses
• Ancestors were tree dwellers that ran along
  branches and jumped from tree to tree, gliding
  wings first evolved then the ability to flap came
  later.
• Ancestors were land dwellers that leapt after
  their prey, wings served to trap or knock down
  prey and over time became large enough to fly.

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Feathers

• Modified scales
• Two main functions
• Provide lift for flight
• Conserve body heat
• Types of feathers
• Down feathers insulation
• Contour feathers streamline shape, coloration,
  insulation
• Flight feathers on wings and tail for flight

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Parts of a feather
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Structure of the feather

• Follicles tiny pits that feather develops from
• Rachis (Shaft) emerges from the follicle
• Vanes 2 vanes on opposite side of shaft
• Barbs branches of the vane
• Barbules projections on the barbs with
  microscopic hooks
• Keratin protein that makes up the feather

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Care of feathers

• Preening use beak to rub feathers with oil
  secreted by the preen gland at the base of the
  tail.
• Molting or shedding of feathers periodically

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Characteristics of Birds

• Section 42.2

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Skeleton Muscles

• Thin, hollow bones fused together
• Sternum breastbone is attachment point for
  flight muscles
• Pygostyle last fused vertebrae that supports the
  tail feathers
• Flight muscles account for 50 of birds weight

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Metabolism

• Endothermic therefore require large quantities of
  food to generate heat
• Aquatic birds have a layer of fat to insulate
• Cannot go through long periods of time without
  food

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Digestive Excretory Systems

• Path of food mouth ? esophagus ? crop ? 2-part
  stomach (proventriculus gizzard) ? small
  intenstine with bile from liver ? large intestine
  ? cloaca ? vent
• Path of wastes blood ? kidneys ? ureters ?
  cloaca (mixes with feces) ? vent

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Digestive System
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Respiratory System

• Highly efficient
• Path of air nostrils ? trachea ? branched
  bronchi ? lungs (25) or air sacs (75)
• Air sacs
• 9 total
• Stores excess air
• Allows for oxygenated air in lungs during exhale
  and inhale

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Respiratory System
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Circulatory System

• Rapid heartbeat
• Up to 1000 beats per minute!
• 4 chambered heart
• Like mammals

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Nervous System Sense Organs

• Large brains (relative to body size)
• Some birds have color vision and/or binocular
  vision
• Some birds have a developed sense of smell
• Sense of hearing also important

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Reproduction

• Sperm movement testies ? vasa deferentia ?
  cloaca ? females cloaca
• Egg movement ovary ? oviduct ? fertilized by
  sperm ? addition of shell ? cloaca ? vent

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Nest Building Parental Care

• Lay eggs in nest
• Methods of rearing young
• Precocial active as soon as hatch
• Atricial helpless when born
• One or both parents incubate eggs by sitting on
  them and covering them with their brood patch
• Thickened, featherless patch of skin on abdomen

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What type is this?
Video
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Migration
Video

• Seasonal movement of birds from one habitat to
  another
• Cues to help navigate
• Position of sun and stars
• Topographical landmarks
• Magnetic field
• Air pressure
• Ornithologist biologist that study birds

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Classification of Birds

• Section 42.3

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Diversity

• Beak and claws infer diet and habitat
• Most widespread terrestrial animal on planet
• 23 orders of birds

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Order Anseriformes

• Examples swans, geese, and ducks
• Aquatic
• Webbed feet
• Flattened bill
• Precocial young, care by female

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Order Strigiformes

• Examples owls nocturnal raptors
• Sharp, curved beak
• Sharp talons
• Keen sense of hearing to detect prey

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Order Apodiformes

• Examples hummingbirds swifts
• Small, fast-flying
• Tiny feet
• Long, narrow beak

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Order Psittaciformes

• Examples parrots, parakeets, macaws, cockatoos,
  cockatiels
• Live in the tropics
• Strong, hooked beak for opening seeds
• Two toes forward, two toes backward for climbing
  perching
• Highly vocal

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Order Picformes

• Examples woodpeckers toucans
• Nest in tree cavities
• Diversity of bills based upon diet
• Same feet as parrots

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Order Passeriformes

• Examples familiar birds (robins, blue jays,
  cardinals, etc)
• perching birds 3 toes forward, 1 toe backward
• songbirds males produce songs to attract mate
  and warn away other males
• Syrinx produces sound at base of trachea

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Order Columbiformes

• Examples pigeons doves
• Plump-breasted, small heads
• Short neck, legs, and beak
• Crop secretes nutritious milk-like fluid to feed
  young
• Crop milk

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Order Ciconiiformes

• Examples herons, storks, raptors, penguins
• World-wide distribution
• Habitat determines adaptations
• Many are wading birds

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Order Galliformes

• Examples turkeys, pheasants, chickens, grouse,
  quail
• Fowl
• Terrestrial birds
• Plump-bodies with limited flying ability

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Order Struthioniformes

• Examples ostriches emus
• Worlds largest birds
• Reduction in toe number to allow for fast running