BIRDS
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I. Characteristics
A. Phylum: Chordata Class: Aves
1. Birds are endothermic reptile-like
animals with an outer covering of
feathers, two legs used for walking or
perching and front limbs modified into
wings that usually do not have useful
claws, and they have feathers.
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2. Birds have:
Feathers
Hollow bones
Forearm modified wings
Toothless beak
**Egg tooth
Streamlined
Hard shell
**Usually 4 toes
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**Toe pattern (one in back 3
forward)
Wishbone
Keel
Right aorta
**Nucleated RBC
**Air sacs
**No diaphragm
**Sclerotic bone in eye
Bone fusion
18-35 cervical bones
***Similar characteristics
with reptiles
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II. Feathers and Flight
A. Birds have three different types of
feathers contour feathers, powder and down
feathers.
1. Contour feathers are large feathers
that cover a bird’s body and wings.
2. Certain contour feathers, known as
flight feathers are long and stiff.
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3. Down feathers grow underneath and
between the contour feathers.
4. Down feathers are short, soft, and fluffy.
These feathers trap warm air close to a bird’s
body, insulating the bird.
5. Baby birds of many species area covered
with down feathers for a period of time after
they hatch.
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6. Powder feathers are important to birds
that live on or in water.
7. As they grow, these feathers release a fine
white powder that repels water and keeps it
from penetrating the layer of down feathers.
8. Birds also produce waterproof oil in
special glands near their tail.
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C. Characteristics of feathers
1. Feathers on the bird are twice as heavy as the
bones.
2. The height or lift from the air occurs on the top of
the wing.
3. Each feather has a set of muscles to allow
spreading the feathers apart or keeping them
together.
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D. Origin of Flight
1. There is the hypothesis called
Areberial hypothesis of flight.
2. There were animals that leaped fro
limb to limb to get food.
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3. Eventually there were animals such
as the flying squirrel, flying lizards,
flying frogs, flying snakes and flying
fish.
4. The theory is that a birds forearm
evolved into a wing and the pectoral
muscles evolved for flight.
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5. Flying is a good way to avoid predators.
6. The theory states that the feathers
evolved from scales for thermal regulation.
(Birds are endothermic)
7. They became bipedal (walk on 2 limbs) to
increase ground speed.
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E. Power of lift
1. The power for flight comes from the
primaries.
2. The power of lift comes from
secondary and then primaries.
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3. Clipping birds feathers to control distance
of flight- clip primaries.
4. To reduce drag (pulls bird backward) the
bird is stream lined.
5. To land the bird “crashes” by grabbing on
a twig or water with their feet.
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6. Flight speed:
Song birds: 20mph
Duck:
40mph
Eagle/attack: 120mph
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F. Types of Wings
1. Elliptical wing- not good for long distance.
Great for maneuvering, non-migrating, glides
very well.
2. Migrating birds feathers- more pointing,
longer, not good for maneuvering. Good for
high speed and long distance. Example- High
speed is much longer and wider.
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3. High-speed wing- wing are tapered, may
have swept back wing look.
4. High lift slotted wing- vultures, buzzard’s
wide wings lots of slotted wings. Good for
thermal soaring.
5. Thermal soaring: Uses the heat and wind
pattern in the afternoon to soar.
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JOKE TIME
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G. Migration
1. Irregular migration is not usual. This
is when birds will migrate to find food.
2. Displacement- When young of the
year gets pushed out from parents.
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H. Types of migration
1. Piloting- Migration by land marks, geese.
Parents take their young and the young will
follow. If parents take the wrong way the
young will continue year after year to go the
wrong way.
2. Orientation- Use the sun to know which
way to go- north or south.
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3. Navigation- this migration is the
most difficult to understand. Lots of
research has been done and many birds
are missing because of it.
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Joke Time
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I. When to migrate
1. Ultimately it is how much food is left or
not left will determine when birds start to
migrate.
2. It is thought that birds are genetically
predetermined to know when to migrate.
3. The male birds are the first to migrate.
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4. Female birds are second to migrate.
5. Males need to establish territory. If the
males migrate to early they will die from cold
and lack of food.
6. The more dominant males will come first
and the less dominant males will come
second.
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7. The less dominant males have a
higher survival rate than the more
dominant males.
8. Survival also depends on the
amount of fat that is on the bird, if they
are able to survive low amounts of
food.
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II. Anatomy of a bird
A. Feeding
1. Birds have high metabolic rates and burn
many calories just to keep warm. Birds need
to eat large amounts of food.
2. Carnivorous birds such as hawks and
eagles catch prey in razor-sharp talons and
slice them to pieces with a pointed beak.
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3. Insect-eating birds do everything from
picking insects off leaves and branches to
catching them on the fly.
4. Their tongues are often equipped with a
brush like structure at the tip for lapping up
nectar and fruit juices.
5. Fruit-eating and seed-eating birds may
have short, stout beaks or long, sharp ones,
depending on the fruit or seed eaten.
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6. The digestive system of birds, much like
that of reptile shows specializations for
carnivores and herbivores diets.
7. Many birds have organs called crop and
gizzard.
8. Crop is an organ that food can be stored
and moistened before it enters the stomach.
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9. The gizzard is a specialized muscular
part of the stomach that often contains
small bits of gravel swallowed by a bird.
10. The muscular wall grind the gravel
and food together, thus crushing food
particles and making them easier to
digest.
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B. Respiration
1. The respiratory system of birds is
extremely efficient at taking in oxygen and
eliminating carbon dioxide.
2. Bird’s lungs are connected at both the
anterior and posterior to large air sacs in the
body cavity and bones.
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3. When a bird inhales, air travels through
passageways that lead into the lungs.
4. Some of this air remains in the lungs,
where gas exchange occurs.
5. Most of the air goes through the lungs
into posterior air sacs.
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6. When a bird exhales, air from the
posterior air sacs passes into the lungs
for gas exchange.
7. Birds are able to remove oxygen
from air when they inhale as well as
when they exhale.
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C. Internal transport
1. Birds have four-chambered heart
and two separate circulatory loops.
2. One half of the heart receives
oxygen –poor blood from the body and
pumps this blood to the lungs.
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3. Oxygen –rich blood returns to the
other side of the heart to be pumped
throughout the rest of the body.
4. Bird’s heart beats fast-from 1501000 beats per minute.
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Joke Time
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D. Excretion
1. Birds eliminate nitrogenous waste filtering
them from the blood in the kidneys.
2. Urine, which contains wastes in the form
of uric acid, flows to the cloaca through the
ureters.
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3. Most water is reabsorbed in the
cloaca, leaving uric acid crystals in a
white paste like form.
4. These crystals are “bird droppings.”
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E. Response
1. Birds are quite intelligent animals.
2. Bird’s cerebrum, which controls such
behaviors as flying, nest building, care of
young, courtship and mating.
3. The cerebellum’s also well developed.
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4. Birds have extraordinarily well developed
eyes. Their eyesight is reflected pair of
sizable optic lobes in the brain.
5. Birds see color very well in many cases
better than humans.
6. A hawk can see 400 times better than a
human.
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7. Bird’s eye is very similar to humans but
hey have pectin. It is unknown what the
purpose of this is.
8. A bird blinks different than humans. In
birds the lower eyelid comes up to close the
eye.
9. A bird has a third eyelid, it is clear and it
can’t be seen.
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10. Ocean birds have a temporary contact
lens to go over their eyes so they can see
under water.
11. Birds usually have a broader range of
vision. A human can see at 85-90 degree
angles. A hawk can see at 110-degree
angels.
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12. Humans have 9,000 taste buds in their
mouth. A bird- 37. A bird has the same basic
tastes: sweet, sour, bitter and salty.
13. Birds lack external ears; they have ear
openings in their head. Many bird species
can hear quite well. Example- owls
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F. Reproduction
1. The reproductive system of birds is similar
to that of reptiles. Both males and female
reproductive tracts open into the cloaca.
2. In many female, birds, only one side of
the reproductive tract develops, this is to
minimize weight.
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3. Birds have a hard outside shell; their
internal structure and membranes are similar
to those of reptiles.
4. Most birds incubate their eggs until the
hatch.
5. Incubation varies from specie to specie
about 13 days to more than 50 days.
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6. Sex chromosomes in humans XX
(female) Xy (males) In aves=
Wu(female) WW(male)
7. In birds the female determines the
sex of the offspring.
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8. Expected ration 50/50 of sex. Some
species are different some ducks- 40%
female, 60% male. House sparrow,
45% female 55% male. Red winged
black birds 16% female 84% male.
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9. Many birds are monogamies – only
have one mate for a lifetime.
Monogamies – 93%
Polygamous- 3%
Polyandry - 1%
Promiscuous - ½%
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10. Most species of birds have very unique
courtship rituals.
11. Male birds do 99% of chirping or calls.
This is to call for his female or to stake our
territory rights.
12. Many birds will undergo courtship
behaviors, dancing, fighting, fluffing and
many other characteristics.
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G. How birds fit in the world
1. Birds are very important to identify
pollution, disease or other health
issues.
2. Birds are very important in the
ecosystem. Help to control the insect
population and small rodent population.
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3. Birds also help to pollinate flowers.
4. Some species of birds help to clean
up waste-vultures.
5. Some species of birds are hunted.
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The End
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