Living in Groups

Question 1

Extreme example of group living?

Answer 1

Bracken cave bats - up to 40 million in May and June

Question 2

Why are there so many bats at Bracken Cave? (2)

Answer 2

Exploiting the migration of the fall army worm-moth, feeding on insects in the jet stream

Maternal colony - May/June, when populations are highest is where energy demands are greatest for milk production

Question 3

Social learning in patch group living? Detriments?

Answer 3

Animals imitate others, giving highest rates for optimal patch selection.

However, this is depended on patch size and value, as this affects competition

Question 4

Theories of predation for group living? (4)

Answer 4

Selfish herd theory
Predator satiation
Reduced vigilance
Predator confusion

Question 5

Selfish herd theory

Answer 5

Animals clump together to decrease risk of being targeted - animals on the outskirts are more vulnerable

Question 6

Predator satiation

Answer 6

Predators can only eat so much e.g. cicadas, preyed upon by birds, are eaten in the same amount regardless of pop. size
It’s therefore beneficial to reduce probability of being eaten by living in a large group
BUT relies on single predators

Question 7

Reduced vigilance

Answer 7

Can spend more time foraging/child rearing etc

Might be the other way round - larger groups = greater foraging and reduced vigilance is a consequence of this

Question 8

Predator confusion

Answer 8

Sensory systems only process fixed inputs - behaviours e.g. shoaling interfere with this