1. Chapter 42 Birds Section 2 Characteristics of Birds

2. Feathers Modified scales 2 functions: conserve body heat & provide lift for flight Down feathers- provide insulation Contour feathers- give adults streamlined shape Flight feathers- specialized on wing & tail

3. Feathers- made of keratin Feathers develop from tiny pits in the skin called follicles. Shaft- emerges from the follicle & two vanes-develop on opposite sides of the shaft Maturity- vane has many branches- barbs- many projects from barbs = barbules

5. Feathers Preening- care for feathers- birds rub feathers with beak and secrete oil by a preen gland- located at base of tail Birds molt, or shed to re-grow feathers

6. Skeleton and Muscles Bones are thin and hollow Bones are fused so they are more rigid- provides stability during flight Sternum- breastbone- attachment point for flight muscles Pygostyle- supports tail feathers

10. Metabolism Endothermic- produce body heat Have to eat often- high energy users Conserve body heat- fluff up feathers Aquatic birds have a layer of fat and oil on feathers to keep water from body

11. Digestive & Excretory System Esophagus  crop- stores & moistens food  proventriculus- acid and digestive enzymes begin breaking down food  gizzard- crushes food  small intestines  cloaca Uric acid- waste--- no urine (too heavy)

13. Respiratory System High metabolic rate = high oxygen use of birds Air sacs- redirect air to lungs Efficient breathing

15. Circulatory System Four-chambered heart

16. Nervous System & Sense Organs Complex brain, keen eyesight, good hearing

17. Reproduction Vasa deferentia- sperm pass through small tubes During mating, birds press cloacas together Ovary released to oviduct- egg fertilized by sperm Egg passes from oviduct- out cloaca

18. Nest Building & Parental Care Birds lay eggs in nest---why a nest? Brood patch- parents incubate eggs with a thickened, featherless patch of skin on abdomen

19. Nest Building & Parental Care Two patterns of rearing young Precocial- young can swim, walk, feed as soon as they hatch (ducks, chickens, etc) Atricial- young are born blind, naked, and helpless (hawks, parrots, warblers, etc)

20. Migration Migration- seasonal movement Ornithologists- study birds Earth’s magnetic field changes and gives cues on when to migrate- some monitor position of stars or sun Birds eat double before they migrate

22. REVIEW!!! In what ways does the gizzard compensate for the lack of teeth in birds? Identify the cues birds use to help them navigate during a migration.