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Birds
Birds
Birds
What is a bird?
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Birds are reptile-like animals that
maintain a constant internal body
temperature.
Birds have an outer covering of
feathers; two legs that are covered
with scales and are used for walking or
perching; and front limbs modified into
wings.
What is a bird?
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Feathers separate birds from all other
living animals.
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Feathers are made mostly of protein and
develop from pits in the birds' skin.
Feathers help birds fly and also keep
them warm.
Feathers
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Feathers come in a
variety of shapes,
sizes, and colors.
Feathers
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The two main types of feathers are
contour and down.
Feathers
Barb
Contour feather: Contour
feathers provide the lifting force
and balance needed for flight.
Down feather: Down
feathers trap air close to the
body and keep the bird warm.
Barbule: The hooks on
each barbule fit together,
holding them flat.
Evolution of Birds
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Paleontologists agree that birds
evolved from extinct reptiles.
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Embryos of birds and reptiles develop
within amniotic eggs.
Both excrete nitrogenous wastes as uric
acid.
Bones that support the limbs, and other
skeleton parts, are similar in both groups.
Evolution of Birds
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Archaeopteryx was the first birdlike
fossil discovered.
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Archaeopteryx looked like a dinosaur, but
it had feathers.
It had teeth in its beak, a bony tail, and
toes and claws on its wings.
It may be a transitional species between
dinosaurs and birds.
Archaeopteryx
Evolution of Birds
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Other fossil evidence leads some to
hypothesize that birds and dinosaurs
both evolved from an earlier common
ancestor.
The origin of birds is still not
completely resolved.
New fossils of ancient birds are being
found all the time.
Evolution of Birds
Dinosaurs
Modern reptiles
Modern birds
Ornithischia
(bird-hipped
dinosaurs)
Saurischia
(lizard-hipped
dinosaurs)
Ancestor of
dinosaurs
Reptile ancestor
Archaeopteryx
Form, Function, and Flight
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Birds have a number of adaptations
that enable them to fly, including:
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highly efficient digestive, respiratory,
and circulatory systems
aerodynamic feathers and wings
strong, lightweight bones
strong chest muscles
Body Temperature Control
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Birds generate their own body heat
and are called endotherms.
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Endotherms have a high rate of
metabolism.
Metabolism produces heat.
Feathers insulate a bird enough to
conserve most of its metabolic energy,
allowing it to keep warm.
Feeding
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Birds need to eat a lot of food to
produce the heat energy they need to
maintain metabolism.
Feeding
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Birds’ beaks, or bills, are adapted to
the type of food they eat.
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Insect-eating birds have short, fine bills
that pick ants and insects off leaves and
branches, or can catch flying insects.
Seed-eaters have short, thick bills.
Carnivorous birds shred their prey with
strong hooked bills.
Feeding
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Long, thin bills gather nectar or probe
mud for worms and shellfish.
Large, long bills pick fruit from branches.
Long, flat bills grasp fish.
Beak Adaptations
Coevelution
Feeding
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Birds do not have teeth and cannot
chew.
Many birds have specialized structures
to help digest food.
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The crop is a structure at the lower end
of the esophagus in which food is stored
and moistened.
Feeding
Esophagus
Crop
When a bird eats,
food moves down
the esophagus and
is stored in the crop.
Feeding
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In some birds the crop has a second
function.
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During nesting season, the crop
produces a substance rich in protein and
fat.
Parents regurgitate this to feed their
newly hatched young.
This provides young birds with materials
they need to grow.
Feeding
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Birds that eat meat or fish have an
expandable area in which large amounts
of soft food can be stored.
Birds that eat insects or seeds have a
muscular organ called the gizzard that
helps in the mechanical breakdown of
food.
Feeding
The muscular walls of the
gizzard squeeze the contents,
while small stones grind the
food.
Gizzard
Respiration
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Birds have a highly-efficient way of taking
in oxygen and eliminating carbon dioxide.
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Air enters air sacs.
It flows through the lungs
where gas exchange
takes place.
Respiration
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Air flows in a single direction.
The one-way flow of air:
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constantly exposes the lungs to oxygen-rich
air.
maintains a high metabolic rate.
provides efficient extraction of oxygen,
which enables birds to fly at high altitudes
where the air is thin.
Circulation
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Birds have four-chambered hearts and two
circulatory loops.
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There is complete separation of oxygen-rich
and oxygen-poor blood.
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Oxygen-poor blood from the body is pumped to
the lungs.
Oxygen-rich blood returns from the lungs and is
pumped to the rest of the body.
Bird Heart
Domestic pigeon
Heart
Excretion
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Excretion in birds is similar to that of
most living reptiles.
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Nitrogenous wastes are removed from
the blood by the kidneys, converted to
uric acid, and deposited in the cloaca.
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Most of the water is reabsorbed, leaving uric
acid crystals in a white, pasty form.
Response
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Birds have well-developed sense
organs, which are adaptations that
enable them to coordinate the
movements required for flight.
Response
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Birds have well-developed eyes which
allow them to see color very well.
Most bird species can hear quite well.
Taste and smell are not well developed
in most birds.
Movement
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Some birds, such as ostriches and
penguins cannot fly.
Most birds, however, can fly.
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The skeletal and muscular systems of
flying birds exhibit adaptations that
enable flight.
Movement
Vertebra
Skull
Collarbone
(wishbone)
Pelvic girdle
Strut
Tailbone
Pectoral griddle
Air
space
Sternum
Rib cage
Movement
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Birds have large chest muscles that
power the upward and downward wing
strokes necessary for flight.
Muscles attach to a keel that runs
down the front of an enlarged
breastbone, or sternum.
Movement
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Bones are
strengthened by
struts.
Air spaces make
bones lightweight.
Reproduction
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Both male and female reproductive
tracts open into the cloaca.
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Mating birds press their cloacas together
to transfer sperm from male to female.
Reproduction
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Bird lay amniotic eggs that have hard
outer shells.
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Most birds incubate their eggs until the
eggs hatch.
When a chick is ready to hatch, it
makes a hole in the shell with a small
tooth on its bill.
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Once the bird has hatched, it rests for a
while and lets its feathers dry.
Groups of Birds
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There are nearly 30 different orders of
birds.
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Approximately 20 of those orders are
represented in Ohio
The largest order of birds is the
passerines, or perching birds.
New World Vultures
Order: Ciconiiformes
Example: Turkey Vulture
Characteristics:
- Moderately hooked beak; long, broad and rounded wings;
raptorial feet; head of adults is without feathers
Foraging Technique: high soaring (uses thermals)
Food: carrion
Habitat: open lowland, avoids heavily forested regions
Turkey Vultures
Diurnal Birds of Prey
Eagles, hawks, falcons, etc.
Order: Falconiformes
Examples: Osprey, Bald Eagle, Red-tailed Hawk
Characteristics:
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- Strongly hooked beak; long and usually broad wings,
raptorial feet
Foraging Technique: low patrol, swoops
Food: fish, birds, small mammals
Habitat: coasts – rivers, large lakes
Bald Eagle
Birds of Prey
Swifts and Humming Birds
Order: Apodiformes
Examples: Chimney Swift, Ruby-throated
Hummingbird
Characteristics:
- long, flat, pointed wings, brilliant metallic colors
(hummingbird)
Foraging Technique: hover gleaning
Food: nectar and insects
Habitat: Deciduous or mixed woodland forests; open
areas with scattered trees
Ruby-throated Humming Bird
Woodpeckers
Order: Piciformes
Examples: Pileated Woodpecker, Red-headed
Woodpecker, Northern Flicker
Characteristics:
- strong, usually straight, chisel-like or pointed beak;
moderately long wings; strong zygodactyl feet; decurved
and very pointed nails
Foraging Technique: bark gleaner
Food: insects; Fall – nuts, fruits, acorns, sap
Habitat: deciduous/coniferous forest; open woodland
Woodpeckers
Ecology of Birds
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Birds interact with ecosystems and
humans in many ways.
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Hummingbirds pollinate flowers.
Fruit-eating birds disperse seeds in their
droppings.
Insect-eating birds catch insects,
controlling populations.