Basic Mechanism & patterns of flight in birds. Do search for more examples to gain knowledge. Use reference links to know more about researches. - Apoorva Mathur

1. SCHOOL OF STUDIES IN ZOOLOGY,
JIWAJI UNIVERSITY, GWALIOR
TOPIC - BASIC MECHANISM AND PATTERNS OF FLIGHT IN
BIRDS
PRESENTED TO :-
HEAD OF THE DEPARTMENT,
SCHOOL OF STUDIES IN
ZOOLOGY,
JIWAJI UNIVERSITY
PRESENTED BY :-
APOORVA MATHUR
M.Sc II SEM.

2. SYNOPSIS
• Introduction
• Basic mechanism of flight
• Flight adaptations in birds
• Patterns of flight
• Conclusion
• References

3. INTRODUCTION
• FLIGHT :-
It is the primary mode of locomotion used by most bird species in which they take
off & fly.
• WHY BIRDS FLY?
1) To get away from predators.
2) It makes them better hunters.
3) For feeding.
4) For breeding.
5) To protect themselves from adverse environmental conditions.

4. BASIC MECHANISM OF FLIGHT
Bird flight mainly depends upon :-
• Shape of the wings
• How they move them
Forces that act on a bird in flight :-
• Lift
• Drag
• Weight
• Thrust

5. 1) LIFT -
Lift is the force that directly opposes the weight of a bird and holds the bird in the air. Most
of the lift is generated by the wings. Lift is a mechanical aerodynamic force produced by the
motion of a bird through the air. Because lift is a force, it is a vector quantity, having both a
magnitude and a direction associated with it. Lift is directed perpendicular to the flow
direction.
Lift is a force. From Newton’s second law of motion, a force F is produced when a mass m is
accelerated a:
F = m x a
An acceleration is a change in velocity V with a change in time t.
F = m x (v1 - v0) / (t1 – t2)
F = m x dv/dt
Force causes a change in velocity & a change in velocity generates a force. The equation
works both ways. A velocity has both a magnitude called the speed and a direction
associated with it. Scientists and mathematicians call this a vector quantity. To change either
the speed or the direction of a flow, you must impose a force & if either the speed or the

6. For a body immersed in a moving fluid, the fluid remains in contact with the surface
of the body. If the body is shaped, moved, or inclined in such a way as to produce a
net deflection or turning of the flow, the velocity is changed in magnitude, direction,
or both
Changing the velocity creates a net force on the body. Turning of the fluid occurs
because the molecules of the fluid stay in contact with the solid body since the
molecules are free to move. Any part of the solid body can deflect a flow. Parts facing
the oncoming flow are said to be windward, and parts facing away from the flow are
said to be leeward.
2) DRAG -
Drag is a mechanical force. It is generated by the interaction and contact of a solid
body with a fluid (liquid or gas). For drag to be generated, a varying pressure
distribution will produce a force on the body. Th, the solid body must be in contact
with the fluid. There must be motion between the object and the fluid. Drag is
aerodynamic resistance to the motion of the object through the fluid.
As air flows around a body, the local velocity and pressure are changed. Pressure is a
measure of the momentum of the gas molecules and a change in momentum

7. There is an additional drag component caused by the generation of lift. This component
is called induced drag. This drag occurs because the flow near the wing tips is distorted
spanwise as a result of the pressure difference from the top to the bottom of the wing.
Swirling vortices are formed at the wing tips, and there is an energy associated with these
vortices. The induced drag is amount of energy lost to the tip vortices. The magnitude of
induced drag depends on the amount of lift being generated by the wing and on the wing
geometry. Long & narrow wings have less end edges (tips) and more stable wing area
than shorter wider wings so they have less drag.

8. 3) WEIGHT -
The weight of an object is defined as the force of gravity on the object and may be
calculated as the mass times the acceleration of gravity, w = mg. Gravity affect
birds. Birds work against gravity by flapping their wings to keep them in flight. They
push the air down which pushes their body up according to Newton’s third law.
4) THRUST -
Wings function as propellers. During the downwards wing beat the primary wing
feathers stand out at right angles to the rest of the wing and to the line of flight. The
primary feathers are twisted for a split second but their twisting gives the propeller
motion. In a bird wing which oscillates up and down, the feathers must continually
change position to produce the thrust. In slow flight only the tips of the wings act as
propellers; in fast flight or on take off, the entire outer wing may go through the
motion.

9. ANGLE OF ATTACK -
Wings are angled slightly, which allows them to deflect the air downward and produce
lift. The slight angle of the wings is called the angle of attack. If the angle of attack is
great then the wing will produce a lot of drag. If the angle is small then the wing won't
produce enough lift.
The amount of lift depends on the speed of the air around the wing and the density of
the air. To produce more lift, the object must speed up and/or increase the angle of
attack of the wing.
Speeding up means the wings force more air downwards so lift is increased. Increasing
the angle of attack means the air flowing over the top is turned downwards even more
and the air meeting the lower surface is also deflected downwards more, increasing lift.

10. FLIGHT ADAPTATIONS IN BIRDS
BODY CONTOUR
The birds have a spindle-shaped body to offer less air resistance during flight. This
helps the birds to conserve energy and become more efficient at flying.
COMPACT BODY
The body of a bird is compact, dorsally strong and ventrally heavy to maintain
equilibrium in the air. Their wings are attached on the thorax, light organs like lungs
and sacs are positioned high, heavy muscles placed centrally are other features that help
in flight.
BODY COVERED WITH FEATHERS
Feathers are smooth, directed backwards, and closely fitting which make the body
streamlined and reduce friction during flight. It lightens the body weight. They also have
a wide surface area for striking the air. Feathers add to the body buoyancy. It insulates
the body and prevents any loss of heat from the body. This helps the birds to bear low
temperatures at higher altitudes.

11. FORELIMBS MODIFIED INTO WINGS
The forelimbs are modified into wings which is the only organ of flight. These consist of a
framework of bones, muscles, nerves, feathers, and blood vessels. Wings have a large surface
area. They also support the bird in the air. Wings have a thick strong leading edge with a
concave lower surface and a convex upper surface. This helps in increasing the air pressure
below and reducing the air pressure above. Thus the bird can fly upward and forward during
flight.
BIPEDAL LOCOMOTION
The anterior part of the body of a bird helps in taking off during flight. Hindlimbs help in
the locomotion on land. They can support the entire body weight of a bird.
SHORT TAIL
The tail bears long feathers that spread like a fan and function as a rudder during flight. They
also help in balancing, lifting, and steering while flying and perching.
LIGHT AND RIGID ENDOSKELETON
The birds have a very stout and light skeleton. The bones are hollow, filled with air sacs. The
bones are fused and many birds have bone marrow in only few parts. Birds lack teeth. The

12. DIGESTIVE SYSTEM
Birds have a very high rate of metabolism. Therefore, food digests rapidly. Length of the
rectum is reduced because of the minimum undigested waste. They lack gall bladder which
reduces the weight of the bird.
RESPIRATORY SYSTEM
Respiratory system of birds is designed in such a manner that the food is oxidised rapidly
and a large amount of energy is liberated. Since the metabolism rate is higher, a large
number of oxygen molecules are required by the body. For this, the lungs are provided
which occupy the entire space between the internal organs.
CIRCULATORY SYSTEM
Rapid supply of oxygen is required by the blood due to rapid metabolism rate in birds.
Therefore, birds require an efficient circulatory system. Birds have a four-chambered heart
that performs double circulation. Also, the birds contain a large amount of haemoglobin in
their red blood cells which helps in the quick aeration of body tissues.
WARM BLOODED
The temperature of the body of a bird remains high and does not change with the change

13. Fig. Respiratory system of birds
Fig. Bones and muscles in birds

14. Ulna : Larger of paired bones between the humerus
and the wrist, to which secondaries attach.
Pneumatic bones :
Hollow bones containing
extensions of air sacs.
Fig. Sternum : The breastbone – Site of
attachment of flight muscles and ribs.

15. Fig : Pygostyle : The last bone at the posterior
end of the vertebral column, which supports the
tail feathers and related musculature. It is formed
by several fused vertebrae.
Fig. Pectoralis
The large breast muscle that powers the downstroke of
flight by depressing the wing at the shoulder

16. PATTERNS OF FLIGHT IN BIRDS
GLIDING
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.
SOARING
Birds that can maintain flight without wing flapping. The use rising air currents.
FLAPPING
Birds flap their wings with an up-and-down motion. This propels them forward. The entire
wingspan has to be at the right angle of attack, which means the wings have to twist with
each downward stroke to keep aligned with the direction of travel.

17. HAWKING
This techniques refers to flying out and up from a perch, then back again in a circular motion.
This is used by flycatchers and warblers to hunt for insects “on the wing”.
HOVERING
The bird appears as if hovering in place. Hummingbirds can do this at will because of a flexible
shoulder joint that enables the bird to create lift during the up and down stroke. Other birds
such as Kingfishers can hover briefly by flying into the wind.
UNDULATING FLIGHT
This describes a kind of rollercoaster style where the bird flaps its wings during the rising phase
& then glides as it descends. Woodpeckers and finches can be seen using this style of flight.
V OR J FORMATION
Wide variety of birds fly together in a symmetric v-shaped or a j-shaped coordinated formation,
also referred to as an "echelon", especially during long distance flight or migration. Birds make
this pattern in order to save energy and improve the aerodynamic efficiency. The flock is
arranged in a V pattern, each bird slightly higher than the other to take advantage of the lift that
is generated by the wingtip vortex of the bird in front of it. The lead bird and outside positions
of the formation are the most physically difficult, so the flock members take turns at these
positions to help conserve energy. Used by migratory birds such as geese, ducks and swans.

19. Fig. Undulating Flight Pattern
Fig. Hovering Flight
Pattern

20. CONCLUSION
Flight is the primary mode of locomotion used by most bird species. Flight in birds mainly
depends upon :-
1) Shape of the wings.
2) Forces acting on the bird in flight such as :-
• Lift
• Drag
• Thrust
• Weight
3) Different morphological & anatomical adaptations in birds for flight.

21. REFERENCES
• Biomechanics of bird flight : Https://www.Ncbi.Nlm.Nih.Gov/pubmed/17766290
• Https://www.Grc.Nasa.Gov/WWW/k-12/virtualaero/bottlerocket/airplane/drag1
• Https://www.Grc.Nasa.Gov/WWW/K-12/airplane/lift1.Html
• Https://www.Ncbi.Nlm.Nih.Gov/pubmed/19880724
• Https://www.Ncbi.Nlm.Nih.Gov/pmc/articles/PMC4992708/
• Https://www.Ncbi.Nlm.Nih.Gov/pmc/articles/PMC3311889/

22. THANK YOU