Transcript Birds
Birds Class: Aves 29 Orders 8,600 species Thought to have come from reptiles because they: 1. Lay amniotic eggs 2. Have scales on legs General Characteristics Endotherms-heat comes from within the body Feathers help with insulation 4 chambered heart Must have good senses Vision: most birds have good eyesight Visual and motor areas of the brain are well developed What is a bird? Reptile like Maintain a constant body temperature Have feathers Have 2 legs that are covered with scales The majority of birds can fly, but those that can’t move by walking, running, or swimming. Ratites-birds that don’t fly keel is subtle or absent and lacks muscles to fly Carinates-have a keel and can fly Feathers Made mostly of protein called keratin, and develop from pits in the bird’s skin. Help with flight and insulation 3 Types of feathers: Contour Down Provide lift and balance needed for flight Trap air close to body for insulation Powder down (in birds that are around water) Powder repels water 1. Vane 2. Rachis 3. Barb 4. Afterfeather 5. Hollow Shaft Evolution of Birds Thought to have come from extinct reptiles Archaeopteryx: First birdlike fossil From Jurassic Period (150 mya) Looked like a small running dinosaur except it had feathers Unlike birds, it had teeth in it’s beak, a bony tail, and toes and claws on it’s wings Comparison of Reptiles and Birds Embryos develop in amniotic eggs Excrete waste in the form of uric acid Bones in front and hind limbs are very similar Bodies are Modified for Flight Bones: Organs: Honeycombed (hollow) inside Makes the bird lighter Missing some to make bird lighter Only 1 ovary No teeth (food is ground up in the gizzard) Crop (part of the digestive system used to store food) Beak: Make of keratin (lighter than bone) Different shapes for different diets and is also aerodynamic Flying Requires good coordination and lots of energy Flap wings using large pectoral muscles (breast) anchored to a keel on the sternum Some have wings adapted for soaring and only have to flap occasionally Others have to flap continuously to stay in flight (hummingbird) Wings work using Bernoulli’s principal Video on Pectoral Muscles Advantages of Flight Hunting and scavenging Catch insects (good source of nutrition) Escape predators Can migrate farther Digestion Birds don’t have teeth, so they have to break down food using a crop At the end of the esophagus, it stores and moistens food before it enters the stomach In some birds, during nesting season, the crop produces a protein rich substance that they regurgitate to their young Beaks Adapted to the food they eat Insect eating: short, fine bills Seed eating: short, thick bills Carnivores: strong, sharp, hooked bills Nectar eating: long, thin bills Fish eating: large, long bills Digestion Birds that eat insects or seeds have a gizzard Forms part of the stomach Birds swallow stones or small pebbles to help grind up the food Waste leaves through the cloaca Respiration When birds inhale, the air passes into air sacs in the body cavity and in the bones. It then passes through the lungs on the way out of the body. While in the lungs, oxygen is absorbed into the blood stream. This is a one way flow of oxygen rich blood. Helps birds fly at high altitudes where air is thin. http://bcs.whfreeman.com/thelifewire/conte nt/chp48/4802001.html Circulation Have a 4 chambered heart. Oxygen rich blood is separate from oxygen poor blood. Response Have well adapted sense organs. The brain is relatively large for the body size. Have highly developed eyes that see color very well. Taste and smell are not as developed. Reproduction Reproductive tracts open into the cloaca in both male and female birds. Sex organs sometimes shrink when not mating. Mating birds press their cloaca together to pass sperm into the female (not all birds have a penis) Birds incubate their amniotic eggs until they hatch. Chicks use a small tooth on their bill to crack the egg. After exiting the egg, it rests and allows the feathers to dry. Groups of Birds Loons and Grebes Loons •There are about 5 species of loons •4 can be found in the US •Gather food by diving and chasing fish Grebes •27 species worldwide •7 can be found in the US •Food gathering similar to the loon •Found in more diverse habitats than loons Groups of Birds The Pelagics Albatross 14 species worldwide Petrels 20 species worldwide Shearwater 70 species worldwide Groups of Birds Pelicans and relatives (ex. Cormorants, boobies, and frigatebirds) Found in all aquatic ecosystems Have 4 toes connected by a web Groups of Birds Parrots (Macaws, lovebirds, and cockatoos) •Colorful and noisy •Use feet to hold food •Most typically mate for life •Beaks can crack open seeds, nuts •Tongues have a bone that can help them tap into fruit •Very social Groups of Birds Perching Birds (ex. Sparrows, crows, mockingbirds, and cardinals) Called passerines Largest order of birds Many are songbirds Herons and relatives (ex. Storks, ibises, spoonbills, herons, and cranes) Adapted to wading in aquatic habitats Groups of Birds Ostriches and relatives (ex. Emus, rheas, cassowaries, and kiwis) Flightless Must move by running or swimming Cavity Nesting Birds (ex. Barbets, toucans, and woodpeckers) Multicolored Live in holes in trees, mounds, or underground tunnels Groups of Birds Birds of Prey (ex. Condors, hawks, owls, eagles, and falcons) Also known as raptors Fierce predators with hooked bills Large wingspans Sharp talons Ecology of Birds Can pollinate flowers (mockingbirds), seed dispersal, and control insect populations. Migration Usually seasonal Some species use stars to navigate others use landmarks or the earth’s magnetic field Indicators for environmental health Songbird eggs became very fragile because of the pesticide DDT and their population was nearly extinct Common Birds around here Common Birds around here Common Birds around here Common Birds around here Common Birds around here Common Birds around here Common Birds around here Common Birds around here Common Birds around here Common Birds around here Common Birds around here Common Birds around here