Migration Flashcards
Where do many organisms migrate to?
Areas with more favorable environmental conditions
Disadvantages of Migration
Animals who migrate invest a large quantitiy of energy to travel long distances
Advantages of Migration
It is beneficial in the long term as they can thrive in a more suitable environment and they can avoid conditions of metabolic adversity by shortage of food and low temperatures
Ringing
A metal band (carrying the birds unique number and the investigators contact details) is attached to the birds leg.
If the bird is recaptured and it’s information reported then this record of it’s movements contributes to an overall picture of the migratory behavior of their species
Tagging
A small circular tag is attached to the underside of the hind wing of an organism which carries a code to be entered into a database.
If the tag is recovered at a later date and the information is recorded, the route and distance covered by the animal can be determined.
Colour Marking
Bright coloured marks and flags enable scientists to observe the birds with binoculars without needing to recapture them
Transmitters
Glued to the animals body or implanted under its skin.
The transmitters in emit signals that are picked up by satellites as they pass over head.
The signals are beamed back to ground station and the information relayed to scientists.
Most precise, animal does not need to be recaptured but more expensive and could cause drag
Innate Behaviour
Inherited and inflexible, plays a primary role in migratory behavior.
The pattern is performed in exactly the same way by every member of the species.
It occurs in response to an external stimulus.
Learned Behaviour
Gained by experience, flexible and as a result of trial and error and through sharing of knowledge and skills between individuals
These play a secondary role in migration
Experiments about Migration
Cross Fostering
Displacement
Investigating Directional Tendencies
Inestigating Directional Tendencies
A hand reared bird is placed in an orientation cage with an ink pad on the bottom
The bird leaves marks when trying to fly off, indicating the direction the bird is trying to fly.
The results suggest that the young bird posses genetic information about the direction in which they are to migrate suggesting innate behavior.
Cross Fostering Experiment
Herring gulls are non-migratory and lesser black-backed gulls are migratory.
Eggs were switched and the behavior if the offspring were observed.
The black-backed gulls raised by non-migrating herring gulls did migrate = innate behavior
The herring gulls raised by migrating lack-backed gulls did migrate with their foster parents = learned behavior
Displacement Experiment
A large number of starlings were displaced from their usual migratory route.
Adult birds who had migrated before showed a combination of innate and learned behavior by compensating for the displacement.
Young birds followed a direction based on purely innate behavior and arrived in a different place.
