1. Class Aves: Birds

2. Characteristics of Class Aves Adaptations for flight (feathers/wings) Adaptations for flight (feathers/wings) Endothermic/High metabolic rate Endothermic/High metabolic rate Vertebral column modified for flight Vertebral column modified for flight Bones lightened by numerous air spaces Bones lightened by numerous air spaces Horny bill/beak Horny bill/beak Lack teeth Lack teeth 4 chambered heart 4 chambered heart Super efficient respiratory system Super efficient respiratory system Lay amniotic eggs Lay amniotic eggs

3. Miscellaneous Largest class of terrestrial vertebrates Largest class of terrestrial vertebrates Evolved from small carnivorous dinosaurs about 150 mya. Evolved from small carnivorous dinosaurs about 150 mya. Oldest known bird is archaeopteryx, which had many similarities with dinosaurs (teeth, claws on wings, long tail) Oldest known bird is archaeopteryx, which had many similarities with dinosaurs (teeth, claws on wings, long tail)

4. External Structures: Integumentary A bird’s feathers are called its plumage. A bird’s feathers are called its plumage. Feathers have 3 main purposes: Feathers have 3 main purposes: Provide lift and aid steering during flight Provide lift and aid steering during flight Waterproofing and preventing excessive heat loss Waterproofing and preventing excessive heat loss Courtship Courtship Feathers are modified scales made of keratin which are molted annually Feathers are modified scales made of keratin which are molted annually Feathers consist of a central shaft (rachis) and the vane (the rest of the feather) Feathers consist of a central shaft (rachis) and the vane (the rest of the feather) The vane is made of barbs and barbules that interlock to provide strength and catch air The vane is made of barbs and barbules that interlock to provide strength and catch air Thin skin and scales on legs and feet Thin skin and scales on legs and feet Cere – skin around the beak Cere – skin around the beak

7. Types of Feathers Contour feathers – cover the body wings and tail Contour feathers – cover the body wings and tail Down feathers – insulating feathers Down feathers – insulating feathers Filoplume feathers – sensory functions Filoplume feathers – sensory functions Birds preen in order to stay clean, remove dead skin cells, and remove parasites Birds preen in order to stay clean, remove dead skin cells, and remove parasites An oil gland at the base of the tail provides natural lubrication and waterproofing for skin and feathers An oil gland at the base of the tail provides natural lubrication and waterproofing for skin and feathers

9. The Skeleton & Muscles Lightweight, yet strong due to air sacs Lightweight, yet strong due to air sacs Flight birds have MANY mitochondria and produce LARGE amounts of ATP in their muscles. Why might this be? What about chickens and turkeys? Flight birds have MANY mitochondria and produce LARGE amounts of ATP in their muscles. Why might this be? What about chickens and turkeys?

11. Flight: The Airfoil

12. Nutrition & Digestion Most birds are ALWAYS hungry! They have to eat a lot to keep up with the energy necessary for flight. They have ridiculously high metabolisms. Most birds are ALWAYS hungry! They have to eat a lot to keep up with the energy necessary for flight. They have ridiculously high metabolisms. A bird’s beak and tongue are indicative of its food source. For example, the beak of a bald eagle if specialized for tearing meat off live prey. (Remember the activity.) A bird’s beak and tongue are indicative of its food source. For example, the beak of a bald eagle if specialized for tearing meat off live prey. (Remember the activity.)

13. Nutrition & Digestion Continued Crop – stores & moistens food, does not digest it; it allows birds to eat even when their stomach is full so that food is constantly moving through their body and providing energy. Crop – stores & moistens food, does not digest it; it allows birds to eat even when their stomach is full so that food is constantly moving through their body and providing energy. Proventriculus – stomach Proventriculus – stomach Ventriculus – gizzard kneads and crushes food; birds swallow rocks/sand in order to enhance the function of the gizzard Ventriculus – gizzard kneads and crushes food; birds swallow rocks/sand in order to enhance the function of the gizzard

14. Circulatory System 4 chambered heart that is large and beats very rapidly 4 chambered heart that is large and beats very rapidly Veins return blood TO the heart, arteries take blood away FROM the heart to the rest of the body; Pulmonary vessels carry blood to and from the lungs. Veins return blood TO the heart, arteries take blood away FROM the heart to the rest of the body; Pulmonary vessels carry blood to and from the lungs.

15. Respiratory System Birds have a greater rate of oxygen consumption than any other vertebrate, because they must maintain a high metabolic rate. Birds have a greater rate of oxygen consumption than any other vertebrate, because they must maintain a high metabolic rate. Birds have air sacs that extend from lungs that constantly cycle air with every breath in and out. Birds have air sacs that extend from lungs that constantly cycle air with every breath in and out.

16. Respiration

17. Thermoregulation Birds are endothermic. What does this mean? Birds are endothermic. What does this mean? When birds get hot, they don’t sweat, but rather pant like a dog. When birds get hot, they don’t sweat, but rather pant like a dog. In order to stay warm, they will tuck their bill under their feathers and possibly pull one leg, then the other, close to their body. In order to stay warm, they will tuck their bill under their feathers and possibly pull one leg, then the other, close to their body.

18. Nervous System Birds have big brains relative to their size. The bigger brains function in visual learning, feeding, courtship, nesting, and migration. Birds have big brains relative to their size. The bigger brains function in visual learning, feeding, courtship, nesting, and migration. Vision – birds see in color, have eyelids AND a nictitating membrane. Birds that hunt prey usually have eyes that face forward. Birds that eat insects, fruit, or seeds usually have eyes on the sides of their heads. WHY? Vision – birds see in color, have eyelids AND a nictitating membrane. Birds that hunt prey usually have eyes that face forward. Birds that eat insects, fruit, or seeds usually have eyes on the sides of their heads. WHY? Smell – birds do not have a highly developed sense of smell Smell – birds do not have a highly developed sense of smell Hearing – Birds can hear EXTREMELY well Hearing – Birds can hear EXTREMELY well

19. Excretion Birds have a cloaca and NO bladder. Birds have a cloaca and NO bladder. They excrete uric acid. They excrete uric acid.

20. Reproduction & Development All birds are oviparous – they lay eggs that develop outside of the body All birds are oviparous – they lay eggs that develop outside of the body Most birds compete for mates through courtship behavior. Most birds compete for mates through courtship behavior. Over 90% of birds are monogamous for a season and some are monogamous for life. Over 90% of birds are monogamous for a season and some are monogamous for life.

21. Chicks Altricial birds – helpless at hatching; must be fed, kept warm, and grow rapidly. Altricial birds – helpless at hatching; must be fed, kept warm, and grow rapidly. Precocial birds – almost independent at hatching; usually covered with down and can walk, run, swim, and feed themselves almost immediately. Precocial birds – almost independent at hatching; usually covered with down and can walk, run, swim, and feed themselves almost immediately. Birds that don’t fly are usually precocial. Why might this be? Birds that don’t fly are usually precocial. Why might this be?

22. Migration & Navigation The instinct to migrate is usually initiated by the changes in the length of daylight that accompanies the change in seasons. The instinct to migrate is usually initiated by the changes in the length of daylight that accompanies the change in seasons. Birds use two forms of navigation: Birds use two forms of navigation: Route-based navigation – keeping track of landmarks Location-based navigation – using the angle of the sun, changes in air pressure, and the Earth’s magnetic field to guide them