2Class: Aves 29 Orders 8,600 species Thought to have come from reptiles because they:1. Lay amniotic eggs2. Have scales on legs
3General Characteristics Endotherms-heat comes from within the bodyFeathers help with insulation4 chambered heartMust have good sensesVision: most birds have good eyesightVisual and motor areas of the brain are well developed
4What is a bird? Reptile like Maintain a constant body temperature Have feathersHave 2 legs that are covered with scalesThe majority of birds can fly, but those that can’t move by walking, running, or swimming.Ratites-birds that don’t flykeel is subtle or absent and lacks muscles to flyCarinates-have a keel and can fly
6FeathersMade mostly of protein called keratin, and develop from pits in the bird’s skin.Help with flight and insulation3 Types of feathers:ContourProvide lift and balance needed for flightDownTrap air close to body for insulationPowder down (in birds that are around water)Powder repels water
9Evolution of Birds Thought to have come from extinct reptiles Archaeopteryx: First birdlike fossilFrom Jurassic Period (150 mya)Looked like a small running dinosaur except it had feathersUnlike birds, it had teeth in it’s beak, a bony tail, and toes and claws on it’s wings
11Comparison of Reptiles and Birds Embryos develop in amniotic eggsExcrete waste in the form of uric acidBones in front and hind limbs are very similar
12Bodies are Modified for Flight Bones:Honeycombed (hollow) insideMakes the bird lighterOrgans:Missing some to make bird lighterOnly 1 ovaryNo 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
14Flying Requires good coordination and lots of energy Flap wings using large pectoral muscles (breast) anchored to a keel on the sternumSome have wings adapted for soaring and only have to flap occasionallyOthers have to flap continuously to stay in flight (hummingbird)Wings work using Bernoulli’s principalVideo on Pectoral Muscles
15Advantages of Flight Hunting and scavenging Catch insects (good source of nutrition)Escape predatorsCan migrate farther
16DigestionBirds don’t have teeth, so they have to break down food using a cropAt the end of the esophagus, it stores and moistens food before it enters the stomachIn some birds, during nesting season, the crop produces a protein rich substance that they regurgitate to their young
17Beaks Adapted to the food they eat Insect eating: short, fine bills Seed eating: short, thick billsCarnivores: strong, sharp, hooked billsNectar eating: long, thin billsFish eating: large, long bills
18Digestion Birds that eat insects or seeds have a gizzard Forms part of the stomachBirds swallow stones or small pebbles to help grind up the foodWaste leaves through the cloaca
19RespirationWhen 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.
20Circulation Have a 4 chambered heart. Oxygen rich blood is separate from oxygen poor blood.
21Response 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.
22ReproductionReproductive 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.
23Groups of Birds Loons and Grebes Loons There are about 5 species of loons4 can be found in the USGather food by diving and chasing fishGrebes27 species worldwide7 can be found in the USFood gathering similar to the loonFound in more diverse habitats than loons
24Groups of Birds Albatross 14 species worldwide Petrels The PelagicsAlbatross14 species worldwidePetrels20 species worldwideShearwater70 species worldwide
25Groups of BirdsPelicans and relatives (ex. Cormorants, boobies, and frigatebirds)Found in all aquatic ecosystemsHave 4 toes connected by a web
26Groups of Birds Parrots (Macaws, lovebirds, and cockatoos) Colorful and noisyUse feet to hold foodMost typically mate for lifeBeaks can crack open seeds, nutsTongues have a bone that can help them tap into fruitVery social
27Groups of BirdsPerching Birds (ex. Sparrows, crows, mockingbirds, and cardinals)Called passerinesLargest order of birdsMany are songbirdsHerons and relatives (ex. Storks, ibises, spoonbills, herons, and cranes)Adapted to wading in aquatic habitats
28Groups of BirdsOstriches and relatives (ex. Emus, rheas, cassowaries, and kiwis)FlightlessMust move by running or swimmingCavity Nesting Birds (ex. Barbets, toucans, and woodpeckers)MulticoloredLive in holes in trees, mounds, or underground tunnels
29Groups of BirdsBirds of Prey (ex. Condors, hawks, owls, eagles, and falcons)Also known as raptorsFierce predators with hooked billsLarge wingspansSharp talons
30Ecology of BirdsCan pollinate flowers (mockingbirds), seed dispersal, and control insect populations.MigrationUsually seasonalSome species use stars to navigate others use landmarks or the earth’s magnetic fieldIndicators for environmental healthSongbird eggs became very fragile because of the pesticide DDT and their population was nearly extinct