L8 - Animal Migration Flashcards
What is migration?
The regular movement back and forth between two relatively distant locations by animals that use resources concentrated in these different sites (Alcock 2013)
Name and describe the 3 types of orientation/ navigation?
- Pilotage: steering a course using familiar landmarks
- Compass orientation: ability to head in a particular compass direction without reference to landmarks.
- True navigation: the ability to orientate toward a goal such as home/breeding area without use of landmarks and regardless of its direction
What are the costs of migration?
- Extra weight that must be carried to build sufficient energy reserves
- Temporary atrophy of reproductive organs
- Increase in muscle contraction efficiency
- Altered metabolism enabling bird to store fats efficiently
- Risk of death during trip
- Must be well adapted to multiple habitats (predators, parasites)
Give an example of how energy reserves can influence migration route
In red-eyed vireo:
- With normal energy reserves = fly over Gulf of Mexico
- With low energy reserves = track coast and do not fly over Gulf of Mexico
What are examples of why an animal would migrate?
- More quality food
- Longer day hours to forage/ hunt
- Lower predation
- More suitable climate
What is Emlen’s funnel experiment and what did it show?
Experiment - Birds were placed in a funnel with an ink pad on the floor
Results - Bird orients in a particular compass direction depending on the time of year e.g hopped towards North in Spring
This showed the bird’s pre-migratory restlessness
What Cues Can Animals Use To Navigate?
- Visual
- Olfactory
- Atmospheric pressure
- Sound
- Geomagnetism
What study showed that birds can use sun position to base their navigation on?
Kramer (1951)
- Birds that have had their endogenous diurnal clock phase-shifted predictably misinterpret the geographical direction of the sun
- Showing birds use a time-compensated sun compass!
Which animals use solar cues for navigation?
Birds, frogs, butterflies, turtles, lizards, rodents
What does anosmic mean?
Having no sense of smell
What plays a crucial role in homing pigeons? And how do we know this?
Olfactory signals
- Impair olfaction with xylocaine (causes birds to be anosmic)
- Causes disruption of initial bearings of release from sites 24-155 km away from home l
Will turtles make it back to their home island if downwind or upwind? And what are two potential reasons?
Downwind - olfactory or infrasound
What changed the results from Emlen’s funnel experiment? What were the new results?
Removing the magnetic field led to there being no orientation in the birds
Where is the Captive European robins magneto-receptor located?
In their right eye
Which animals use magnetoreception to aid migration?
Birds, butterflies, moths, turtles, fish
