1. Class Aves: Birds
18A

2. Common Characteristics
Covered with feathers
Have thin-walled, often hollow bones (these bones are not lighter, but they are denser, stiffer, and stronger)
Require enormous amounts of energy
Demand lots of oxygen for respiration
Are endothermic (warm-blooded)
Have high metabolism
Have no teeth (durable beak made of keratin is just as efficient but lighter)
Oviparous

4. Feathers Care Gland at base of tail produces oil
Preening- bird applies oil to feathers with its bill while it adjusts and smoothes its feathers
Oil provides waterproof shield

5. Feathers Function Shape the body to make the bird aerodynamic
Help birds retain heat
Serves as cushion- protecting the skeleton during collisions
Help camouflage the bird or attract and identify a mate

6. Feathers Structure Grow from a structure in the skin called a papilla
The feather consists of
Flat vane which consists of parallel rows of thin barbs with parallel rows of thin barbules that are hooked together
Rachis- shaft within the vane
Quill- hollow shaft from papilla to vane

7. Feathers
Two types
Down feathers make up the underlayer providing insulation as and cushion
Contour feathers are the vaned feathers that cover most of the body and give external shape and color, and also the flight feathers which extend from the wings and tail
Barbules do not interlock in down feather

8. Feathers Fully developed feathers, likes scales and hairs are dead
Bird sheds or molts old feathers and replaces them

9. Appendages Forelimbs (wings) for flying
Penguins and some other flightless birds use their “wings” to swim
Lower part of the hind limbs are usually thin and covered with scales
Most birds have 3 or 4 clawed toes

10. Wings
Elliptical- short and wide providing for quick takeoffs and landings, low speed flight, and maneuverability (sparrows, woodpeckers)
High-speed- thin, long, tapered shape that produces minimum drag (terns, swifts, sandpipers)
Soaring- long and thin and resemble the wings of a glider; enable the bird to expend minimal energy in staying aloft but provide little maneuverability (gulls)
High-lift- wings are large and convex; they give a great amount of lift even at low speeds, allowing birds to carry large prey (hawks, eagles, owls)

11. Feet
Wading- long, thin, widely spread toes that distribute weight; thin toes and legs permit movement in water without creating turbulence
Swimming- webbed and serve as paddles
Climbing- two toes in front and two behind to provide grip and balance
Running- toes are strong and hoof like and support heavy birds as they run along the ground
Grasping- toes with talons (long curved claws) designed to grasp and kill prey
Perching- three front toes and one back toe; a locking device closes toes and remains tightly closed until the bird releases it

13. Skeleton
A bird’s skeleton has numerous air-filled cavities within the bone
Elongated upper jaw (maxilla) and lower jaw (mandible) are elongated and form the bill
Vertebrae of the tail are free moving and help in guiding flight
The trunk vertebrae, the flat ribs, and the sternum (breastbone) are fused to make the trunk a rigid framework
central ridge of the breastbone called the keel provides attachment for flight muscles.
Clavicles (collarbones) are enlarge and fused, forming the “wishbone” which also provides attachment for flight muscles

14. Bird Systems

15. Digestion Birds need a lot of energy to fly so they have to eat a lot.
They also have to be able to digest food quickly. They can’t carry heavy food around while flying and they need the energy.

16. Bill The type of bill depends on the bird’s diet
Spearing fish- long slender
Probing for insects- long slender
Cracking and crushing seeds- short and stout
Tearing prey- hooked pointed bills
Filtering- bills contain throat pouch

17. Digestion
Esophagus
Crop- stores food. It is an enlargement of the esophagus
Proventriculus- first part of the stomach, produces digestive juices
Gizzard- second part of the stomach, where grinding of the food (mechanical digestion) occurs. It has thick muscular walls. Birds swallow gravel to help grind the food.
Intestines- final digestion and absorption
Cloaca- serves as the common opening for the intestine, kidney duct, and reproductive organs

18. Respiration Air Sacs- unique to birds
The lungs are unable to supply all the oxygen the bird needs to maintain its high metabolism.
As the bird exhales oxygen rich air goes from the air sacs to the lungs, so the bird has oxygen rich air passing through their lungs as they breathe in and out.
Also make the bird light because they are located in places where fluids or fat would be in other organisms.

19. Respiration High metabolism produces a lot of heat
Respiration is important because it helps cool the bird
They can rapidly move air in and of their air sacs. The exiting air carries heat.

20. Circulation 4 chambered heart
Oxygenated and deoxygenated blood completely separated

21. Circulation
Relative to its body size birds have the largest hearts of all vertebrates
heart beats per minute (avg human heartrate is bpm, could be around 200 bpm during exercise)

23. Excretion Pair of dorsal kidneys
Waste empties directly from the kidneys into the cloaca
Birds do not store urine or feces

24. Sound
Syrinx- song box, enlargement of the trachea just above where it divides to enter the lungs
Syrinx and associated muscles produce sound
Bird Mimicry

25. Sensing Reptiles, amphibians, and fish rely heavily on smell and taste
Birds rely heavily on hearing and sight
Vision of a hawk is 8 times more acute than that of a human
Owls can see in light 1/10 to 1/100 the brightness required by man to see
Light receptors in the retina of a bird’s eye are packed from 2-5 times more tightly than those in humans
Falcon
Eagle goat
Hawk- iguana
Bird of Prey- Snake
Bird of Prey- Seal
Bird Orders

26. Behaviors Mating rituals Birds of Paradise mating dance
Prairie Chicken mating dance