CHAPTER 12 SECTION 1 Birds

Characteristics of Birds Endotherm Vertebrate that has feathers Four-chambered heart Lays eggs Most can fly Scales on feet and legs

Adaptations for Flight Bones are nearly hollow Bones of a bird’s forelimbs form wings  Flying birds have large chest muscles to move wings Flight feathers  Extend from contour feathers, help it balance and steer

2 Types of Feathers Contour  Large feathers that give shape to a bird’s body  Consists of a central shaft and small hairlike projections called BARBS  Hooks hold barbs together  Sometimes “unzip” during flight  Birds “zip” barbs back together during preening  Long feathers that extend from contour feathers are called flight feathers Down  Specialized to trap heat, soft  Near bird’s skin

Obtaining Oxygen/Circulatory System System of air sacs, connects to lungs  Enables birds to obtain more oxygen Heart with 4 chambers  2 atria  2 ventricle  Right side of heart = oxygen-poor blood to lungs  Left side of heart = oxygen-rich blood to body Four chambered heart does not mix blood, blood circulates to body’s cells has plenty of oxygen

Respiration

Obtaining Food Use their bills  Help birds feed quickly and efficiently  Hawk– pointy, curved bill  Duck– kitchen strainer Crop  Internal storage tank, used for storing food inside the body after swallowing  Connected to stomach Gizzard  Squeeze and grinds partially digested food  Contains small stones

Keeping Conditions Stable Since they are endotherms they need a lot of energy to keep body temperatures stable and for flight Eat about ¼ of body weight per day Use feathers to keep warm

Reproduction and Caring For Young Internal fertilization Lay eggs Shells are harder than reptiles Female lays eggs in a nest Either parent can sit on the eggs to incubate them  Eggs must stay warm in order to develop Stay with their young until they are able to fly

Birds in the Environment 10,00 species Adapted for living in diverse environments  Legs  Claws  Bills Perching Birds– goldfinches and mockingbirds Woodpeckers– tools for chipping wood Hummingbirds– pollinators Ostriches– cannot fly but can move quickly Predator birds– eat pest animals