1. Birds
Chapter 42

2. Origin and Evolution of Birds
Section 42.1

3. Important characteristics
Feathers – only birds have them!
Wings – modified forelimbs
Lightweight, rigid skeleton – hollow bones
Endothermic metabolism – o F
Unique respiratory system – most efficient
Beak – no teeth
Oviparity – eggs incubated by parents

4. 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

5. 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

6. Origin of flight 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.

7. Feathers Modified scales Two main functions: Types of feathers:
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
video

8. Parts of a feather

9. Structure of the feather
Follicles: tiny pits that feather develops from
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
video

10. 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

11. Characteristics of Birds
Section 42.2

12. 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 bird’s weight

14. 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

15. 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

16. Digestive System

17. 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

18. Respiratory System

19. Circulatory System Rapid heartbeat 4 chambered heart
Up to 1000 beats per minute!
4 chambered heart
Like mammals

20. 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

21. Reproduction
Sperm movement: testies  vasa deferentia  cloaca  female’s cloaca
Egg movement: ovary  oviduct  fertilized by sperm  addition of shell  cloaca  vent

22. Nest Building & Parental Care
Lay eggs in nest
Methods of rearing young:
Precocial: active as soon as hatch
Altricial: 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

23. 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

24. Classification of Birds
Section 42.3

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

26. Order Anseriformes Examples: swans, geese, and ducks Aquatic
Webbed feet
Flattened bill
Precocial young, care by female

27. Order Strigiformes Examples: owls & nocturnal raptors
Sharp, curved beak
Sharp talons
Keen sense of hearing to detect prey

28. Order Apodiformes Examples: hummingbirds & swifts Small, fast-flying
Tiny feet
Long, narrow beak

29. 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

30. Order Picformes Examples: woodpeckers & toucans Nest in tree cavities
Diversity of bills based upon diet
Same feet as parrots

31. 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

32. 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

33. Order Ciconiiformes Examples: herons, storks, raptors, & penguins
World-wide distribution
Habitat determines adaptations
Many are wading birds

34. Order Galliformes
Examples: turkeys, pheasants, chickens, grouse, & quail
Fowl
Terrestrial birds
Plump-bodies with limited flying ability

35. Order Struthioniformes
Examples: ostriches & emus
World’s largest birds
Reduction in toe number to allow for fast running

36. Bird Beaks and Feet