refers to migration of birds

1. ORIGIN IN
BIRDS.
MIGRATION OF
BIRDS
MSC ZOOLOGY
SEM (II)
ARPITA JALADAR

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CONTENT
S
 Theory of origin of birds
 Bird evolved from bipedal dinosaurs
 Why birds need to migrate
 Pattern of migration
 Migratory adaptations in birds
 Advantages and disadvantages of migration
 Conclusion
 Reference

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Introduction : Birds are a diverse group of animals with over
10,000 species worldwide, ranging in size from the tiny
hummingbird to the ostrich, which stands over 9 feet tall. The
evolution of birds and their migration patterns are fascinating
topics that have intrigued scientists for years. In this presentation,
we will explore the origin of birds and their migration patterns .
Section 1: Origin of Birds The origin of birds is a topic of debate
among scientists. While the exact origins of birds are not fully
understood, many scientists believe that birds evolved from a
group of small, feathered, theropod dinosaurs that lived more
than 150 million years ago during the Jurassic Period. Recent
discoveries of fossils in China have shed light on the evolution of
birds. In 1996, a team of Chinese paleontologists discovered the
fossilized remains of a small theropod dinosaur, which they
named Sinosauropteryx .

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The fossil showed clear evidence of feathers, and its anatomy was
similar to that of early birds . Other fossils, such as Archaeopteryx,
have also provided insight into the evolution of birds. Archaeopteryx
lived around 150 million years ago and had feathers, wings, and other
bird-like features, but also had many characteristics of dinosaurs.
These fossils suggest that birds evolved from dinosaurs and that the
evolution of feathers was an important step in the process.
Section 2: Bird Migration -Bird migration is a fascinating
phenomenon in which birds travel long distance , often across
continents or oceans, to breed, feed, or seek better climate conditions.
Migration can be seasonal, with birds traveling from their breeding
grounds to their wintering grounds, or it can be nomadic, with birds
moving in response to food or weather conditions .

5. . Birds use a variety of cues to navigate during migration, including the
position of the sun and stars, the Earth's magnetic field, and visual
landmarks. Many birds also have an innate sense of direction, which
helps them navigate . There are many reasons why birds migrate,
including : Breeding: Birds migrate to areas where food and nesting
sites are plentiful, and where they can mate and raise their young
successfully . Food: Many birds migrate to areas where food is more
abundant during the winter months . Climate: Some birds migrate to
areas with milder climates to avoid harsh winters or hot summers .
Conclusion: In conclusion, the origin of birds is still a topic of debate,
but many scientists believe that birds evolved from small, feathered,
theropod dinosaurs that lived over 150 million years ago.
Bird migration is a fascinating phenomenon that allows birds to travel
long distances to find food, breeding grounds, or better climate
conditions. Studying the evolution of birds and their migration patterns
can help us better understand the natural world and the complex
interactions between animals and their environments.

6. MIGRATION
It is a collective term of Immigration and
Emigration
Immigration occurs when new individuals are
introduced
It results in the increase in population size
Emigration is when individuals leave a population
It results the decrease in population size

7. Why Birds need to Migrate?
Birds need to migrate for
1. Food
2. Shelter
3. Reproduction
4. Predator Avoidance
5. To Avoid Climate Extremes

8. Patterns of Migration
• The Old birds that have traveled many times in their
life forms the front line
• Then comes the Young ones Traveling for the first
time
• Next are the females
• Injured and old Birds are present in the back rows
• Birds tend to fly in flocks rather than to fly alone
• More Obvious pattern is V shaped
• It helps to save energy and provides max Speed

9. MIRGRATORY ADAPTIONS IN BIRDS
Birds that migrate have natural features that help them in their journeys.
A majority of migratory birds have longer and more pointed wings than
non-migratory birds or birds with shorter migrations. This aerodynamic
wing structure helps to reduce air resistance during flights, thus allowing
for more efficient flights.
Migrants usually prefer flying in clear weather conditions with a good
tailwind (when the wind is blowing in the same direction as the bird’s
flight). Many birds prepare for migration by becoming hyperphagic, a
condition where due to an alteration in the hormone levels, the bird starts
eating a lot of food which gets stored in its body as fat. This excess fat
can be used as an energy source during the long journey. Some migrants
have been known to almost double their body weight by storing fat in
the weeks leading up to the migration!

10. ADVANTAGES
Migration provides birds with
I. New environment provides them with
greater supply of food
II. They are provided with shelter and
territory
III. Better suited environment
IV. Avoidance from the Predators
V. Reproductive success as more
offspring are produced
VI. In this way they face different
environmental conditions and can meet
the needs of their young ones more
efficiently.
VII. Moreover ,their survival chance
occur more by evolution.
DISADVANTAGES
I. Many young are not, able to reach
the destination because they die during
the course of the continuous and
tiresome journey.
II. Sudden changes in the climate such
as storms and hurricanes, strong
current of wind, fog are the causes for
the death of a sizeable number of
migrants.
III. Sometimes man-made high tours
and light houses cause the death of
migratory birds.
IV. Man themselves are responsible for
the death of the migrants. They shoot
at these poor birds just for their own
leisure and amusement.

11. CONCLUSION
 Birds Migrate to survive
 Migration plays important role in their Evolution
 Several Climatic Factors triggers the process of Migration
 Migration is not always advantageous
 Birds have adapted themselves for Migrations either short or
long distances Not all the birds migrate but some of the
individuals of a population migrates

12. REFERENCE
 Newton, I. (2008). The Migration Ecology of Birds. Elsevier.
 Chan K (2001). "Partial migration in Australian landbirds: a
review". Emu. 101 (4): 281–292
 Edwards, Darryl B.; Forbes, Mark R. (2007). "Absence of
protandry in the spring migration of a population of Song
Sparrows Melospiza melodia". Ibis. 149 (4): 715–720
 Berthold, Peter (2001). Bird Migration: A General Survey.
Oxford University Press. p. 67
 Guillemain, M.; Sadoul, N.; Simon, G. (2005). "European
flyway permeability and abmigration in Teal Anas crecca, an
analysis based on ringing recoveries". Ibis. 147: 688

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