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Behavioural Ecology > Group Living > Flashcards

Flashcards in Group Living Deck (14)
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1
Q

What did Williams and Hamilton suggest about group behaviour?

A

It’s the benefit to the individual that drives aggregation behaviour

Aggregation will reduce the risk of predation (dilution)

2
Q

What is predator swamping?

A

The idea that synchronised emergence can ‘swamp’ predators reducing capacity to catch prey

3
Q

What is the selfish herd effect?

A

Individuals around the edge of a group are more at risk, therefore individuals will move around to gain a safer position in the aggregation

4
Q

What is the confusion effect?

A

It is hard to focus on one individual when many others are moving within line of sight

5
Q

What is the oddity effect?

A

Predators prefer to attack odd looking individuals because they are easier to focus on

High saliency individuals will be more easily noticed by predators

6
Q

Give an example of communal defence

A

Study on nesting birds showed that artificial nests placed near the colonies suffered lower predation then the nests placed near solitary nests

7
Q

How does group vigilance benefit an individual?

A

Higher chance of a predator being spotted when in a larger group

Spend less time looking around for predators and more time feeding

8
Q

How might group vigilance be a problem?

A

Dilution reduces the vigilance of the individual but the overall vigilance of the group may be reduced, especially when there is competition over food resources

9
Q

What is the ‘Trafalgar effect’?

A

Individuals know when the predator is approaching before it is even in sight

Usually due to alarm calls

10
Q

What are the advantages to not cheating in a group?

A

More vigilant individuals are less likely to be targeted by predators, also more vigilant individuals will spot alarm flights etc. quicker

11
Q

What are sentinels?

A

A small number of individuals watching from a look out point for predators while the rest forage in relative safety knowing they are being watched over

E.g. meerkats

12
Q

Why do some animals take the role of sentinels?

A

Predation risk for sentinels is reduced as they tend to be the first to spot the predator and therefore the first to respond - could be a selfish reason

13
Q

How could information sharing on food availability/patches be beneficial to an individual?

A

Could be the dilution effect to reduce the risk of predation and allows more time for the individual to feed instead of looking out for predators

14
Q

Give an example of when information sharing benefits an individual

A

Ravens feeding on a carcass could fight off juveniles
However when it reached 6 or more they would give way

Therefore juvenile ravens call out to other ravens to gain access to the carcass