Class Aves: Birds 18A

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

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

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

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

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

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

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

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)

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

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

Bird Systems

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.

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

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

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.

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.

Circulation 4 chambered heart Oxygenated and deoxygenated blood completely separated

Circulation Relative to its body size birds have the largest hearts of all vertebrates 135-570 heart beats per minute (avg human heartrate is 60-100 bpm, could be around 200 bpm during exercise)

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

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 http://www.youtube.com/watch?v=VjE0Kdfos4Y

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 http://www.youtube.com/watch?v=r7lglchYNew Eagle goat http://www.youtube.com/watch?v=VklTs-Tid_I Hawk- iguana http://www.youtube.com/watch?v=9vQuqg5hZYM Bird of Prey- Snake http://www.youtube.com/watch?v=s-sHY1zSA2I Bird of Prey- Seal http://www.youtube.com/watch?v=Ugxq3yLNk6g Bird Orders http://www.allaboutbirds.org/guide/search

Behaviors Mating rituals Birds of Paradise mating dance http://www.youtube.com/watch?v=L54bxmZy_NE Prairie Chicken mating dance http://www.youtube.com/watch?v=s2_wdMmEupQ