Biology lesson within CLIL methodology for bilingual programmes.

1. Bird Migration
 What is migration?
The migration of birds is a natural phenomenon that occurs on a global level.
The migration of birds is the displacement of population where they leave from their wintering
location(wintering area) for an area more suitable for breeding (breeding area). The
displacement produced between both locations is dominated by migratory movements or
migratory trips. They are called migratory routes.
A great number of species migrate annually throughout earth. Some do short distance trips,
while others do trips of tens of thousands of kilometers crossing all types of physical,
ecological o meteorological barriers, such as mountains, deserts, storms, headwinds, etc.
In the case of swallows (Hirundinidae) and house martins (Delichon urbicum) that we are going
to study, their wintering areas are over 10,000 km away from where their nesting takes place.
 How is the migration carried out?
It is done in stages since it lasts several days or even weeks, and, because of this, the birds
must stop to rest and feed at appropriate points. These are called the resting areas.
In Andalucia, resting areas are in Tarifa (Cádiz) while passing along the Straight of Gibraltar and
Doñana.
Many of the largest birds fly in flocks, which helps them conserve energy. V formations allow
the birds to use up to 20% less energy due to the turbulence caused by each preceding bird. To
get height, large gliding birds such as storks and raptors are helped by rising air currents, called
thermal currents. In these flocks they make a circular movement that allows them to stay
in this current; this is known as the cycle.
 Why do birds migrate?
Birds migrate for essentially one reason:
- The lack of food
With changing temperatures, food sources become scarce or inaccessible. The birds need to
search for another place where food is available.
 What are the most common routes?
The 3 in Europe are: (Look on the map)

2. Bird Migration
Western Route
From Central and Eastern Europe the birds go to the Alps or Pyrenees Mountains. Then, the
migration is carried out throughout all of the Iberian Peninsula and meets back together in
Gibraltar. In fact, on days filled of intense migration, one can see thousands of raptors and
storks.
The proximity of both continents, separated by a sea route of barely 14 kilometers, makes
Tarifa a key observing point for one of the greatest natural events in the world.
Central Route:
Crosses Italy and Sicily, and then the Mediterranean Sea, in order to arrive to the African
continent by way of Tunisia.
Eastern Route:
Transited by Northern and Eastern European birds, as well as from Western Asia, which cross
the Balkans, Greece and the Mediterranean. They continue through Lebanon and Israel, finally
arriving to Eastern Africa.
Migratory bird routes at a global level:
Main migratory
bird routes
throughout the
world
 Questions:
- What relationship exists between the beginning of the migration and the availability of food?
- What are the main migratory routes between Europe and Asia?
- Do only birds migrate or do other animals do it too?
- Does the human species migrate? And during antiquity did it also migrate?
- What types of flights are carried out by different species of birds?
- Why is the Straight of Gibraltar so significant when it comes to bird migration?
 Know the common plane and swallow

3. Bird Migration
In the case of swallows (Hirundinidae) and house martins (Delichon urbicum) are birds that we
will see over Seville towards the end of February and beginning of March. They come from
Africa and return to spend the spring-summer in our area. Here they breed.
How are both species? Observe their differences and complete the squares.
Copy the picture in your notebook. Then at home make a drawing of the two species
and their nests. Also search for additional information.
House martins (Delichon urbicum) Swallows ( Hirundinidae )
Ventral part of the body
Size of the tail
Nests
Flight

4. Bird Migration
Answers:
-The differences are:
-The house martin has a white chest
The swallow has a White chest but with an orange bib (on the neck)
House martin open nest Swallow closed nest
House martin short tail Swallow long tail
THe house martin flies at the altitude of a first or second floor
Swallow flies even with the ground

5. Bird Migration