18.1 BIRDSPage 367

BIRD CHARACTERISTICS

Vertebrates ENDOTHERMs

Organisms with a constant internal body temp.Cells of body stay warm & work normally all the

time Only animals w/ feathers Beaks, not teeth Have wings

*Not all can fly! Lay eggs w/ shells

ORIGIN OF BIRDS Earliest fossil of a bird found in 1861

Like a reptile: scales, jaws with teeth, claws on front limbs

Imprint of feathersEvidence birds evolved from reptiles

DIVERSITY OF BIRDS Over 9,000 species of birds 4 Groups

Birds of preyPerching birdsWater birdsFlightless birds

Each bird is adapted to eating a certain kind of food & living in a certain habitat

Lifestyle reflected in its:BeakWingsFeet

BIRDS OF PREY Eat mammals, fish, other birds Sharp, hooked beaks to tear flesh Claws for grasping Examples:

EaglesHawksOwlsFalconsVulturesOsprey

PERCHING BIRDS Insect eaters Long, pointed beaks work like tweezers

Used as drills for boring into wood in search of insects

Examples:WoodpeckersSwifts

SEED EATERSThick, strong beak for cracking seeds

Examples: cardinal, blue jay, robin

FLIGHTLESS BIRDS Lost ability to fly Lifestyle makes flight unnecessary Many are fast runners Examples:

OstrichRheaPenguin

WATER BIRDS Have a variety of beaks, wings, and feet Many have webbed feet (swimming) Some have long legs for wading Some have long wings Examples:

FlamingosStorksSwans

FLIGHT ADAPTATIONS Streamlined Lightweight bones Require large amounts of fuel

Bird’s body releases energy stored in food quickly & efficiently

Cells do this at much quicker rate than other animals

This process creates heat (ENDOTHERMS)

FLIGHT ADAPTATIONS Vision

Avoid flying into thingsSee food from far awayLarge eyesSharp vision

MusclesFlying requires great muscular effortPowerful flight muscles attached to large

breastbone

FLIGHT ADAPTATIONS Bones

Hollow, lightweight bonesCross-supports inside bones for support

BIRD SKELETON

FLIGHT ADAPTATIONS Digestive System

Must take in large and steady amount of food High Energy needs

CROP stores the food and releases it in steady stream for digestion

GIZARD grinds up food for easy digestion

BIRD DIGESTION SYSTEM

FLIGHT ADAPTATIONS Air Supply

Special breathing system – provide blood with blood

In addition to lungs, birds have air sacks to increase amount of oxygen

Heart4 chambered: keeps low and high oxygen

blood separateProvides flight muscles with oxygen

FEATHERS Needed to fly Most feathers: CONTOUR feathers

Interlocking barbs DOWN feathers: fluffier, traps layer of

air next to body – heat, insulation

PHYSICS OF FLIGHT Flying made easer b/c wings provide

LIFT Wing shape is key

Upper surface of wing is rounded Air takes longer to go around curved

upper part than bottom flat surface

PHYSICS OF FLIGHT Air takes longer to go around curved

upper part than bottom flat surface Air above wing must move faster to

cover distance in same amount of time The different air speed above & below

creates difference in air pressurePressure under wing HIGHERThus, more force pushing UP (under wing)

than DOWN (on top of wing)Results in lift

MIGRATION Why? Cold & shortage of food MIGRATE: move to different place during

part of every year Many travel same routes every year

REPRODUCTION Similar to reptiles

Eggs fertilized in female body Eggs must stay warm – have to

INCUBATE Many species - male & female take turns

one finds food, one incubates Attachment b/n male & female called

Pair-Bonds

BIRD EGGS Hard shell

Keeps embryo from being crushed during incubation

Bird egg contains:ALBUMEN & YOLK – provides food for

embryo