migration Flashcards
what are the 4 different definitions for migration
1) the persistent form of locomotion that is straight, direct and unwavering
2) a movement of much longer duration of scale than is undertaken in the general day-to-day activity
3) a seasonal movement where the end points serve as different functions
4) a movement that results in the spatial redistribution of a population
why do animals migrate
animals are adapted to specific environments such as the right food or temp, these conditions may be constant but if they vary the species will have to move to a new location with suitable conditions
what is a generalist
species which can exploit and are adapted to exploit a wide range of habitats unlike specialists which are only adapted to one place
how do animals find their way in simple migrations
- use senses to trace elements
- simple north to south
- compass info from the sun and stars
- learn routes from adults
how do animals find their way using homing
- land marks
- true navigation: compass sense, landmarks, magnetic fields
give an example of some cues which are used to anticipate the season
day length
temperature
what is polarised light
light made up from waves with the vibrations at only one angle, it reflects of things such as rivers or glass which some animals can see. This is then used as a landmark
give an example of a species which learns migration routes from parents
wildfowl- tend to follow their parents that have already learnt the route
give an example of a species which uses local land marks for migration
bee-killing digger wasp- females dig burrows in the sand which are used for a nursery for offspring, use homing to relocate burrow
what is mnemotaxis
‘memory movement’= nativgation through the use of landmarks
what are the 3 possible explanations of how species who return to their natal birthplaces
1) simply remember landmarks, directions and reverse
2) home may be recognisable from a distance- come upon it by chance
3) internal map sense
what is olfactory discrimination
allows individuals to extract an olfactory signal from a background and to make a distinction between different odorant molecules
what is true navigation
when animals can move towards a destination without using familiar landmarks- tested by removing an animal from normal track but can still navigate to reach its goal
give an example of a species which can use true navigation
pigeon - they use an internal compass sense to get within 2-5km away from original point
also use
- magnetic field
- polarised light
- map sense, landmarks
-odour
