Mechanics and Classification of birds migration along with the needs to migrate. it is helpful to learn the mechanics involved in migration specifically elaborating the roles of environmental factors to force the birds to migrate.
2. Contents
Introduction
Why birds need to Migrate?
What triggers migration?
Patterns of Migration
Types of Migration
Migratory Adaptations in Birds
Advantages & Disadvantages of Migration
Conclusion
References
3. Introduction
Bird migration is the regular seasonal movement, often north and south along a
flyway, between breeding and wintering grounds
The path followed is known as flyway
Directed from Arctic to Antarctic and vice versa
Quite ancient activity practiced by Birds
Recorded as many as 3,000 years ago by Ancient Greek authors,
including Homer and Aristotle
4. 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
5. Why Birds need to Migrate?
Birds need to migrate for
1. Food
2. Shelter
3. Reproduction
4. Predator Avoidance
5. To Avoid Climate Extremes
6. What triggers migration? Species specific physiological conditions
The Photoperiod
Gonadal development
Increasing Day length
Changes in Food Supply
Lowering temperatures
7. 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
8. Types of migration
Distance based
1. Long Distance Migrations
Long distance travelled
Non Stop Journey
Energy is met by stored Fat
2. Short Distance Migrations
Short Distance is travelled
Journey Starts from dawn and ends at Dusk
Birds Feed during the stop
9. How Birds find the flyway?
Sun Compass Cues
The sun rises in the east, over headed at noon sets in the west
Celestial Cues
Angle between the north star and horizon decreases towards the equator
Magnetic Compasses
Birds orient themselves by using earth magnetic Field
10. Types of Migrations
Seasonal migration is predictable based on seasonal changes
Latitudinal: This migration is between areas of different latitudes from north to
south and vice versa
Longitudinal movement between different longitudes from east to west or west
to east.
Altitudinal Birds that breed in tall mountains often exhibit altitudinal migration
Loop birds that follow an annual circle are loop migrants.
Nomadic movement is less predictable and can be erratic depending on available
food and water resources.
11. Types of Migrations (Continue)
Irruptive migrations that bring large numbers of birds into unusual areas, most
often in winter
Dispersal juvenile birds are forced away from their hatching grounds and must
seek out their own territories as their parents continue to use the same range.
A leap frog or skip migration is a unique pattern where a northern population
will migrate a greater distance to skip over a sedentary population of the same
species.
Molt: Some birds migrate only to accommodate their annual molting periods.
12. Mechanics of Migration
Long distance migrants store fat 50% of their body weight
Some species start journey early and stop frequently to feed and rest
In clear weather birds fly at altitude 1000 meters
It helps them to prevent strike with any obstacle
Many birds have specific migration routes
13. Disadvantages of Migration
Many young are not, able to reach the destination because they die during the
course of the continuous and tiresome journey.
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.
Sometimes man-made high tours and light houses cause the death of migratory
birds.
Man themselves are responsible for the death of the migrants. They shoot at these
poor birds just for their own leisure and amusement.
14. Advantages of Birds Migration
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.
15. What we can do for migratory birds
Eliminate the poison in your Yard
Protect , restore & Create Habitat
Help Migratory birds in your own yard
Provide them food sources
Provide them Water sources
Provide shelter either natural or artificial
16. 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
17. References
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