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Did you ever Wonder how Birds are able to Fly?American Bald Eagle in Flight
The principles of how birds fly are the same for a bird as
they are for an airplane.
Both the bird and an airplane overcome the downward pull
of gravity by means of lift. Lift is caused by the forces of air
as it moves past the wings. To move forward, both must overcome
the resistance of air as well. Both a bird and an airplane
overcome this resistance by means of a propeller.
In the case of a bird, the propeller is the wing.
A bird does not fly by simply flapping it's wings up and down.
The down stroke is the most important in flight; it moves
upward and backward.
On the down stroke, the wing has it's leading edge lower than
the rear edge. As the wing cuts downward and forward through
the air, the angle and shape of the wing is similar to that of a
propeller blade when it is cutting downward through it's
In addition, each primary feather of the bird is under muscular
control and may be rotated. Often, several of the outermost
primaries are also turned forward so that the leading edge of
each is low and each acts as a small, individual propeller.
When a bird's wing is held at too great an angle to the direction
of flight or when the speed of flight is too slow, the smooth
flow of air over the top surface of the wing is disturbed and
lift is destroyed.
This is known as stalling.
Birds and airplanes are similar in the devices they use to help
correct the condition. If any small wing is held in front of the
leading edge of a large wing, a slot is formed through which air
flows. This air is speeded up; it smoothes out the flow of air
over the top surface of the wing, and to a degree prevents
In birds the winglet (little wing) forms such a slot when it is
The tips of the primaries are also often spread to form slots.
There are almost as many shapes of wings are there are kinds
of birds. Some wings are suited for short bursts of flight, other
wings are suited for flight in ocean winds. A hummingbird's wings
can even allow the bird to fly backwards. Other wings are made
A bird uses it's tail to keep itself steady in flight. The tail
also serves as a flap to slow air speed without stalling, very
similar to how an airplane uses flaps in landing.
Some birds make sharp turns at top speeds. Others fly mostly in
straight lines. The difference is in their tail design. Because
the tail is used like a rudder the feathers are broad and stiff.
These tail feathers open and close like a fan and move up and
down. They also twist to the left or right.
Birds "bank" as they turn. They tilt one wing higher than the
other. Banking holds the underside of the wings. Another way the
bird turns is to beat one wing a little faster than the other.
The most unique flying bird is the hummingbird. It can fly in one
place in the air for long periods of time. Their bodies are
upright. Their wings sweep back and forth. This is like a
helicopter. Since their wings make as much power on the up stroke
as on the down stroke, their muscle structure is not like other
How fast can Birds Fly?
Most songbirds can fly about 20 to 30 miles per hour, but Common
Eiders can fly nearly 50 miles per hour, and Dunlins (shorebirds)
are suspected of reaching nearly 100 miles per hour.
Peregrine Falcons are considered the fastest birds. Experts think
they may reach 200 miles per hour in dives.
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