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Class notes for 18.1: Birds.
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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