+FOLLOW

1. FLIGHT
ADAPTATION
IN BIRDS
BIRDS
•FLIGHT
MACHANISM
BIRDS
•FEATHERS
BIRDS
•PERCHING
MACHANISM

2. Flight Mechanism in Birds
Flight in bird is one of the most complex forms of locomotion in the animal kingdom.
Flight in birds includes hovering, taking off and landing which involves many
complex movements. As different bird species have adapted to specific
environments and other basic needs, they have developed different forms of wings
and varied forms of flight

3. Adaptations For Flight
Any alteration in the structure or function of an animal or any of its parts that
results from natural selection and by which the organism becomes better fitted
to survive and multiply in its environment is called as adaptation. For flight, the
body of birds has been well adapted both Morphologically and Anatomically

4. Morphological Adaptations
Body Contour Spindle shaped body to ensure least wind resistance. High
position of light organs like lungs , air sacs and low position of heavy muscles,
sternum, digestive system etc. Low Centre of gravity in the body

5. Morphological Adaptations
Presence of feathers Makes the body stream-lined and reduces the
friction to the minimum. Very light, hardly adds weight to the bird.
Serves as a blanket enveloping air around the body and adds buoyancy.
Feathers of wings increases the surface area for striking the air.

6. Morphological Adaptations
Forelimbs of birds become modified into unique and powerful propelling organs
called wings which propel the body high up in the air. Mobile Neck and Beak
Mobile neck and beak enables the bird for feeding, nest- building, offence and
defense, preening, etc. Bipedal locomotion The hind limbs can support the body
weight and acts as locomotory organs on the ground

7. .
Morphological Adaptations
Perching Muscles are strongly developed and modified so that when a bird sits
in a perch, the toes automatically grips the perch. Short tail and Tail Feathers
Short tail and Tail Feathers can serve as a rudder during flight and assist in
steering, lifting and counterbalancing of the body during flight

8. Anatomical Modifications
Endoskeleton Light and provides large surface for attachment of muscles.
Muscles on the back are much reduced and flight muscles on the breast are
strongly developed Bones are pneumatic filled with air spaces and air sacs.
Skeletal framework is compact, centralized and relatively rigid due to fusion
of bones.

9. Anatomical Modifications
Digestive Organs Digestive system is efficient with a reduced rectum. In birds
the undigested food is never stored because it would create extra burden of
faeces. Circulatory System Heart is large in size and efficient to keep
completely separated the pure and impure blood.

10. FLIGHT MACHANISM
The shape of a bird’s wing is important for producing lift. The increased speed
over a curved, larger wing area creates a longer path of air. This means the air is
moving more quickly over the top surface of the wing, reducing air pressure on
the top of the wing and creating lift. The angle of the wing deflects air
downwards, causing a reaction force in the opposite direction and creating lift.

11. The fundamentals of bird flight are similar to those of aircraft. Lift force is
produced by the action of air flow on the wing, which is an airfoil. The lift force
occurs because the air has a lower pressure just above the wing and higher
pressure below.

12. FLIGHT MACHANISM
When a bird is gliding, it doesn’t have to do any work. The wings are held out to
the side of the body and do not flap. As the wings move through the air, they
are held at a slight angle, which deflects the air downwards and causes a
reaction in the opposite direction, which is lift. But there is also drag (air
resistance) on the bird’s body, so every now and then, the bird has to tilt
forward and go into a slight dive so that it can maintain forward speed.

13. FLIGHT MACHANISM
Basic Mechanism of Flight Flapping. When a bird flaps, its wings continue to
develop lift, but the lift is rotated forward to provide thrust and it counteracts the
drag and increases its speed. Flapping involves two stages: the down-stroke,
which provides the majority of the thrust, and the up-stroke, which can also
(depending on the bird’s wings) provide some thrust.

14. Basic Mechanism of Flight
Drag Apart from its weight, there are 3 drag forces that resist a bird in flight.
Frictional drag is caused by the friction of air and body surfaces, Form drag is
due to frontal area of the bird. It is also known as pressure drag Lift-induced
drag is due to the Wing tip .

15. FLIGHT MACHANISM
During flight the wings become unfolded, stretched and raised vertically
upwards. These then move downward and forward (down stroke) and finally
upward and backward (up stroke). Down stroke is achieved by the action of
pectoralis minor, so that the wing is lowered down. The wing is raised by the
contraction of pectoralis minor, and other muscles. During down stroke, the
wing is thrust downward like an oar. It moves forward and vertically upwards
with little air resistance for the next powerful down stroke. The body moves
forward in upstroke.

16. PERCHING MECHANISM
Perching is actually maintaining a typical posture by the Birds while taking rest on
a support. The muscles involved in perching are situated in the thigh and calf of
the bird’s leg. The tendons of the perching muscles in birds are extended up to
the four digits in the hind limbs. They flex the four digits of birds in the hind limbs
around a support

17. PERCHING MECHANISM
When the bird is still sitting on a perch and the legs are in the same bent
position, the extensor muscles in the leg remain inactive to keep the claws locked
around the perch. So, the birds can even go for a sleep without the fear of falling.
The perching muscles of birds are modified in such a way that the toes can flex
round a twig when the bird sits on it. When the bird sits on the support, the legs
are bent and put the flexor tendons on stretch which results in spontaneous
bending of the toes around the perch.

18. To unlock the claws of the feet, birds have to raise its body for the
perching position. And after the body is raised to straight posture,
the bird gets ready for a flight again.

19. Thank You