• Reptile-like animals that have maintained a constant internal body temperature • Two legs covered with scales that are used for walking or perching • Front limbs modified into wings • Outer covering of feathers: made mostly of proteins and developed from pits in the birds’ skin • Contour feathers • Down feathers • Powder down feathers • A dinosaur with feathers • Archaeopteryx: first fossil found of an early bird-like animal • Looked like a small, running dinosaur with well-developed feathers • Unlike modern birds, it had teeth, a bony tail, and toes and claws on its wings • It is a transitional species between dinosaurs and birds Adaptations for Flight • Highly efficient: digestive system, respiratory system, circulatory system • Aerodynamic feathers and wings • Strong chest muscles • Endotherm: animal that generates its own body heat and controls its body temperature from within • Include birds, mammals and some other animals • High rate of metabolism compared to ectotherms • Metabolism produces heat • A bird’s feather’s insulate its body enough to conserve most of its metabolic energy • Any body heat that a bird loses must be regained by eating food • The more a bird eats, the more heat energy its metabolism can generate • Small birds must eat more, relative to their body size • Birds beaks, or bills, are adapted to the food that they eat • Crop: structure at the lower end of the esophagus in which food is stored and moistened • Gizzard: a muscular organ that helps in the mechanical breakdown of food • Air sacs: one of several sacs attached to a bird’s lungs into which air moves when a bird inhales; allows for the one-way flow through the respiratory system • Advantages: – The one-way flow of oxygen-rich air helps birds maintain their high metabolic rate – Enables birds to fly at high altitudes where there is little oxygen in the atmosphere • 4 chambered hearts and 2 separate circulatory loops • 2 ventricles • Complete separation of oxygen- rich and oxygen-poor blood • This double-loop system ensures that oxygen collected by the lungs is distributed to the body tissue with maximum efficiency • Similar to that of many reptiles • Nitrogenous wastes are removed from the blood by the kidneys and converted into uric acid • Uric acid is sent to the cloaca • Water is reabsorbed into the body • Uric acid crystals leaving the body are in a white, pasty form • Well-developed sense organs to coordinate the movements required for flight • Brain can quickly interpret and respond to many incoming signals • Brain is large for its body • Well developed eyes • Can hear well • Sense of taste and smell are not well-developed; the olfactory bulbs in the brain are small • Some birds cannot fly • Walk: ostriches • Swim: penguins • Flying birds: many large bones are fused together to form a sturdy frame for flight • Both male and female reproductive tracts open into the cloaca • The sex organs are internal and often shrink inside when birds are not breeding • Amniotic eggs: similar to reptilian eggs but have hard outer shells •There are nearly 30 orders of birds •Some of the better known groups: • Perching birds: • Parrots Passerines (includes songbirds such as larks, • Cavity-nesting birds sparrows and finches) • Herons and their • Pelicans and their relatives relatives • Ostriches and their • Birds of prey relatives • Birds interact with the natural ecosystems and human society in many ways • Disperse seeds, pollinate plants • Migrate long distances • Serve as indicators of environmental health The earliest known bird, The world’s only Archaeopteryx wingless bird is the The Australian lithographica, lived about kiwi of New Zealand. pelican has the 150 million years ago The arctic longest beak in during the Jurassic Period. A bird’s tern makes the the world—up to feathers weigh longest migration 18.5 inches long! more than its each year, flying Birds skeleton does. 20,000 to 25,000 Vertebrates Diversity Birds miles each year Some of the 30 classes of birds: from the Arctic to Common characteristics the Antarctic and 1. Waterfowl (ducks, geese, swans) back again. Beak with no teeth 2. Perching birds, aka songbirds Bipedal (sparrows, crows, cardinals) A hawk can see a mouse Forelimbs modified 3. Gamebirds (chickens, turkeys, from a height into wings peacocks, pheasants) of one mile. Body covered with 4. Woodpeckers & relatives The strike Some parrots feathers 5. Hummingbirds & swifts of the eagle must fly over talon has 500 miles a Endothermic 6. Birds of prey (condors, twice the day to forage Highly efficient hawks, falcons, eagles) power of a for food. 7. Owls rifle bullet. respiratory system 8. Pigeons & doves The only known Hard-shelled poisonous bird 9. Herons, storks, & relatives is the pitohui amniotic eggs 10. Parrots (macaws, lovebirds, cockatoos) from Papua, Extremely diverse! 11. New Guinea Pelicans & relatives (cormorants, A bird’s heart beats frigatebirds) The largest bird 400 times per 12. Ostriches Bald eagles have an is the ostrich. minute while resting average wingspan 13. Flamingos Falcons can and up to 1000 of 6 to 8 feet. times per minute dive at over Feathers are 14. Penguins while flying. 200 mph. unique to birds .