migration in birds and animals

1. Migration
ANIMAL BEHAVIOUR
BS ZOOLOGY

2. Definition:
Migrations can be defined as,
“Persistent and very direct movements taking individuals from one
locale to another clearly defined location, and often to a different habitat.”
Migration:

3. Types of migration:
Migration can be either
Obligate, meaning individuals must migrate, or
Facultative, meaning individuals can choose to migrate or not.
Complete migration is when all individuals migrate.
Partial migration is when some individuals migrate while others
do not.

4. Introduction:
A key feature of migratory movements is that they have very distinct
departing and arriving behaviors. Animals migrate because it benefits them
to do so. For example, it may allow them to escape the rigors of winter or
enable them to reproduce in a safe and/or particularly productive
environment. But there are costs to migration too.

5. Onset of migration:
Is under endogenous control involving the combined action of
•Environmental cues.
•Internal rhythms.
•Under the effect of genes.
Green turtles Chelonia mydas, sockeye salmon Onchorynchus nerka
and blackcap warblers Sylvia atricapilla may seem to have little in
common.

6. Onset of migration:
Thousands of salmon fry must leave the breeding rivers for every fish that
eventually return, making it almost impossible to follow an individual’s
progress. And any laboratory-based research involving these animals must

7. Onset of migration:
also take into account the physiological transition made by the animals as
they move from freshwater to saltwater and back again.also take into
account the physiological transition made by the animals as they move
from freshwater to saltwater and back again.In terms of the ability of
individuals to navigate over long distances it seems likely that animals use
the same cues during migratory movements as they do during other forms
of navigation.It is well documented that the sun, stars, and polarized light
fields are used as compasses by birds.

8. Onset of migration:
And salmon are known to use their sense of smell to home in on their
spawning grounds.
When it comes to finding a very specific location at one or other end of the
migratory journey, a territory that had been used in the previous year, for
example local landmark recognition, must be crucial.

9. Migratory birds and turtles:
Both migratory birds and turtles are able to sense the earth’s magnetic fields
and may be able to use them in navigation.
In turtles: Juvenile turtles are certainly sensitive to changing magnetic
fields in the laboratory, but recent experiments that involved strapping
magnets to the backs of migrating adult turtles and then monitoring their
progress via satellite tracking have failed to show the expected disruption
in their migratory ability. In this case then it would seem that either the
magnetic sense is not important, or that the animals are able to use
information from a variety of different sources.

10. Migratory birds and turtles:
In birds: The annual migrations of Australian silvereyes Zosterops l.
lateral is between their Tasmanian breeding grounds and their Australian
non breeding quarters can however be affected if the bird’s magnetic sense
is disrupted. When Wolfgang Wiltschko and his colleagues subjected
migrating birds to a strong magnetic pulse they found that the orientation
behavior of their subjects differed significantlyMigratory birds and turtles:
to that of their untreated control birds.

11. The genetics of migration:
Further evidence that this is certainly the case has come from the very
impressive body of work on the migratory behavior of European blackcap
warbler (Sylvia atricapilla) populations carried out by Peter Berthold and
Andreas Helbig. Discrete breeding populations of these warblers migrate
to discrete wintering ground.

12. Navigation
Definition:
“Animal navigation is the ability of many animals to find their way
accurately without maps or instruments.”
Example: Niko Tinbergen demonstrated that the female digger wasp (Philanthus
riangulum) is able to return directly to her tiny nest burrow after a provisioning
flight because she first memorizes the relative positions of landmark objects in
her environment. In his experiment Tinbergen surrounded a wasp nest with a ring
of pine cones. Then after the wasp had emerged from the burrow and flown
away, he moved the ring of cones a small distance so that the nest was now
outside of it. On her return the wasp flew to the center of the ring and not to the
burrow.

13. Introduction:
Birds such as the Arctic tern, insects such as the monarch butterfly and fish
such as the salmon regularly migrate thousands of miles to and from their
breeding grounds.

14. Trail laying:
Trail laying and trail following as a navigational method are common throughout
the animal kingdom.
Ants, for example, use pheromone trails as a method by which a number of
foragers can efficiently exploit a newly discovered food source. When it finds a
food source that is too large for it to exploit successfully alone a foraging ant will
return quickly, and by a very direct route, to its nest. As it does so it deposits a
pheromone trail on the ground behind it. At the nest the returning individual
performs stereotyped behaviors designed to recruit others to the food source. By
following the trail these recruits are able to go directly to it. As each of them
returns to the nest they too deposit pheromones and so the trail is reinforced.
Eventually the food source will become exhausted and animals will stop
returning from it.

15. Trail Laying:
No trail reinforcement will take place and quite quickly the trail will
disappear. Their short-lived nature makes pheromone trails a particularly
suitable navigational aid in this situation. If they were too long lasting
many ants would waste valuable foraging time following trails that
provided no reward.

16. Trail laying:
No trail reinforcement will take place and quite quickly the trail will
disappear. Their short-lived nature makes pheromone trails a particularly
suitable navigational aid in this situation. If they were too long lasting
many ants would waste valuable foraging time following trails that
provided no reward.

17. Dead Reckoning:
“Dead reckoning, navigating from a known position using only
information about one's own speed and direction, was suggested by
Charles Darwin in 1873 as a possible mechanism.”
Navigation of this type is variously referred to as path integration or dead
reckoning. The latter is a corruption of the term deduced reckoning and
refers to an individual’s ability to deduce its current position in relation to
another location by taking into account the direction(s) and distance that it
has traveled between the two.

18. Dead Rocking:
•Dead reckoning, navigating from a known position using only information
about one's own speed and direction, was suggested by Charles Darwin in
1873 as a possible mechanism.
•In the 20th century, Karl von Frisch showed that honey bees can navigate
by the sun, by the polarization pattern of the blue sky, and by the earth's
magnetic field; of these, they rely on the sun when possible.
•William Tinsley Keeton showed that homing pigeons could similarly make
use of a range of navigational cues, including the sun, earth's magnetic
field, olfaction and vision.
•Ronald Lockley demonstrated that a species of small seabird, the Manx
shearwater, could orient themselves and fly home at full speed, when
released far from home, provided either the sun or the stars were visible.

19. Prepared By: