3. UNIT
#.The migration of birds
• Migration is the yearly, seasonal journey undertaken by many species of birds.
During this journey, birds cover distances of many kilometres.
• The most common types of migration are those carried out by birds in the spring
and the autumn. In the autumn, they travel from breeding grounds in the north to
wintering grounds in the south, and vice versa in the spring.
Breeding grounds
Wintering grounds
Autumn
migration
Spring
migration
4. • Birds that migrate are called migratory
birds, while birds that remain in one area are
called sedenary birds.
Geese are migratory birds.
A sparrow is an example of a
sedentary bird.
#.The migration of
birds
5. #.Why do birds migrate?
• Birds depend on the amount of available food in an area to survive and raise their
chicks, so when there is a shortage of food in one area, they move to areas where
more food is available.
• Changes in the amount of available food in certain areas are related to changes in
temperature. These changes occur in different seasons in different regions of the
world.
NORTH
An abundance of food in the summer.
Little available food in
the winter.
SOUTH
Available food all year round.
Spring Autumn
6. TYPES OF MIGRATION
1. LATTITUDINAL MIGRATION –
It is the movement of the birds
from south to north and its vice versa.
Ex. The American Golden Plover
the several north American and Eurasian birds
cross the Eqauter to spent winter In deeper
and warmer parts of south America and
Africa.
7. 2. ALTITUDINAL MIGRATION
In india a no. of species during
summer migrate from plains to slope
of himalayas scanadian 1000 of feet
above sea level.
Ex. Commen wood cock
9. 4. PARTIAL MIGRATION
In such cases all the birds of a group
of migratory birds do not leave the
native land, visible throughout the
year.
Ex. Finch, Redbreast
10. 5. ERRATIC MIGRATION
Erratic migration occure in great blue
cuckoos.
In such birds after breeding the
adult and the youngmany stray from
there homes.
11. 6. Sessional migration
• It is of three types –
1.climatic migration –
occures due to dailly or seasonal changes in
the climate of the environment.
Migration of DUCKS and GEES.
14. • Birds that migrate from Africa to Europe to breed in the summer are
called summering or trans-Saharan birds (as they cross the Sahara).
The swallow is a trans-
Saharan bird.
#.Migratory routes
15. The
Sahara
• Birds like swallows, bee-eaters, storks and birds of prey including black kites,
vultures and common kestrels journey from Africa to the Iberian Peninsula to
spend the summer.
Swallows
Black kite
UNIT
5 #. Migratory routes
16. #.Interesting
examples• The Arctic tern travels the longest distance of any migratory bird: it journeys from one
pole to another two times a year, covering 40,000 km.
• Over the course of its life, about 26 years, an Arctic tern can travel up to 1 million
kilometres.
Breeding grounds
Wintering grounds
Migratory routes
17. #.Interesting examples
The white stork provides an example of how the amount of food available affects bird
migration.
• These storks used to come to the Iberian Peninsula to spend the summer and
breed. Then, in the autumn, they migrated to Africa to winter there. However, more
and more storks now winter on the Peninsula.
• This is due to:
• A greater number of rubbish dumps
that provide them with food
throughout the year.
• It is likely that the change is also
related to the higher temperatures
resulting from climate change.
White stork
