Navigation And Homing

Question 1

Why do birds need an internal map/compass?

Answer 1

In order for them to travel animals must have a sense of direction - they have an internal compass

Question 2

What are used as compasses?

Answer 2

Solar,skylight, stellar, lunar and magnetic compasses

Question 3

What animals use solar compasses

Answer 3

Butterflies,birds, fish use the suns position to aid navigation

Question 4

What is provided by the circadian clock for butterflies?

Answer 4

The circadian clock allows butterflies to continuously correct their flight pattern

Question 5

What happens if the butterfly didn’t have timecompensation

Answer 5

The butterfly would fly around in circles as they are following the sun. Directly

Question 6

Are internal clocks linked to the internal compass?

Answer 6

Yes they are as following the sun is not enough for animals to migrate. They need a sense of where the sun is at a given time of day which requires a sense of time

Question 7

How do you know if an animal is ready migrate

Answer 7

Show jittery/flapping behaviour especially in the direction they want to travel

Question 8

What did Kramer use as an experiment on starlings

Answer 8

Placed starlings in cages with the sun as a cue. The birds attempted to fly in a migratory behaviour and escaped in the same direction

Question 9

What happened to the starlings when Kramer released them in cloud cover?

Answer 9

There was a uniform way that they flew off. This want that the cloud cover diminished the consistency of the trajectory by interfering the position of the sun

Question 10

What happened when Kramer added mirrors to the cage?

Answer 10

The mirrors deflected the direction of the sun which altered the starlings escape trajectory

Question 11

What happened when Kramer put the starlings under a different photic regime?

Answer 11

He put them under artificial light/dark cycle which is not in sync to the natural world light/dark cycle which shifted their biological clock. This meant it was no longer in sync

Question 12

What do pigeons user as a sun compass?

Answer 12

The azimuth - movement of the sun

Question 13

What happened when pigeons light/dark regime was shifted by 6 hours

Answer 13

Their compass shifted by 90 degrees - 6 X 15 = 50

Question 14

What is polarised skylight navigation?

Answer 14

They use polarised light as a back up option to guide butterflies as long as patches of sky is present.
The solar radiation is reflected by water in the atmosphere

Question 15

How does polarised skylight navigation work?

Answer 15

The electric field vectors are arranged in concentric circles around the sun
Polarisation is at maximal when the sun is at a right angle.

Question 16

How can you track monarch butterflies migration?

Answer 16

Put butterfly in an opaque drum with skylight visible with no landmarks visible
Tether the butter flight to a light weight rod that will recognise if the butterfly twists or rotates

Question 17

What happens if you remove the light from the opaque drum?

Answer 17

Butterfly will fly in circles

Question 18

How does polarised lskylight navigation work in the monarch butterfly?

Answer 18

Dorsal rime on eye is separated from the main retina of the eye
E-vector orientation is detected by photoreceptors in the dorsal rim area
Photic information is integrated and processed in the brain to enable motor responses to adjust orientation

Question 19

What happens in the experiment on the dorsal rim area of arthropod eye in the locust

Answer 19

If you pain the dorsal rim of the locust eye there will be no change in orientation of the locust if you shift the light
This shows that the DRA is responsible for rotational activity