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8/8/2019 Why Can Birds Fly PP
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Why can birds fly?
By Erin Thomas
8/8/2019 Why Can Birds Fly PP
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Flight for Survival
Flight is the reason that birds still exist.Without it, predators would have caused the
Aves to go extinct millions of years ago. This
special adaptation is unique to birds, excluding
bats and flying insects. The ability to fly enables
birds to find food easier and to escape from
predators.
8/8/2019 Why Can Birds Fly PP
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Physical Adaptations
Over time, birds have adapted to their
surroundings. All systems of their bodies
have changed in order to better equip
them for, well, survival. Throughout theyears, new species have been formed
because of change in environment. The
class of the Aves is not about to go
extinct because of their incredibleadaptability.
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Skeletal Adaptations
No teeth
Fused pelvic bone
Reduction of bones
Hollow and light bones
All of these adaptations
make birds lighter, more
aerodynamic, and morebalanced, which makes
flying possible.
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Muscular Adaptations
A bird¶s pectoral muscles
count for 15-40% of its
body weight (1-2% in
humans) No heavy back muscles
or facial muscles.
(stability and balance)
Supercoracoidius (muscle
that pulls wings back) is
connected to the sternum
rather than the back bone
for even more balance.
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Nervous System Adaptations
The cerebellum in the brain is enlarged in
proportion to size, which is the part of the
brain used for balance and coordination.
Bird BrainHuman Brain
8/8/2019 Why Can Birds Fly PP
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Optics
Proportionally, birds eye¶s are 10-15% larger than
human eyes.
Birds¶ eyes account for 15% of the weight of their head,
while in humans they are only 1% of our head weight. A bird¶s retina is 1-1.5% thicker than mammals¶.
The cones (located in the fovea) are also more
concentrated than humans.
± Bird- 1 million cones/ sq. mm ± Human- 200,000 cones/ sq. mm
Birds can see in color because of special oil droplets in
the retina. These oil droplets also improve contrast and
reduce haze.
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More Optics
A Hawk¶s vision is 8x better than humans
Most birds of prey have two fovea; one central for side vision,
and one temporal for front vision.
S
clerotic ring is a ring of bones around edge of eye. The ringfixes it so eye can't move. Birds make up for the lack of
movement by having really flexible neck.
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Smell and Taste
Birds do not have a very keen sense of smell of
taste.
The kiwi has the best sense of smell.
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Hearing
Birds have some of the best hearing of all
animals.
However, their hearing lacks focus.
Two types of birds use echolocation; Oilbird and
Cave Swiftlet.
Oilbird Cave Swiftlet
8/8/2019 Why Can Birds Fly PP
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Excretory and Digestive System
Birds have no urinary bladder
The cloaca is the common canal for both
reproductive and excretory systems, which reduces
extra weight. Birds have very efficient digestive enzymes
They eat high energy foods to use for flight.
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Respiratory System
Birds use air sacs which are pockets used
along with the lungs to assist breathing
± They also make birds more buoyant
± They cool birds¶ high metabolism
± They cushion deep dives for waterfowl
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The Evolution of Flight
Since the Archaeopteryx (the earliest fossil
found of a bird), flight has changed a lot.
Wing length and shape have changed inorder to best suit the type of food that a
bird needs.
Flight will continue to change
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So why can birds fly?
Birds have adapted over time in order to findfood easier and to flee from predators.
Their bodies have changed in order to make
flight possible. ± Better vision and hearing
± Light weight
± Hollow bones
± Better balance and coordination Birds will continue to evolve and adapt, making
them unstoppable.
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