2. Economic Decisions

Question 1

What kind of decisions are ‘economic decisions’?

Answer 1

How long to spend in one patch

Prey selection: specialist or generalist

Risk sensitive foraging

Social learning and traditions

Question 2

How do you test if something is behaving optimally?

Answer 2

Build a simple model to understand the costs and benefits

Question 3

Total foraging time is found by what equation?

Answer 3

Time spent travelling + Time spent in patch

Question 4

How would you calculate the rate of energy delivered to the ‘nest’?

Answer 4

(Energy gained) / (total time spent foraging)

Question 5

What does this equation calculate?

Answer 5

The rate of energy delivered to the ‘nest’ per foraging outing

Question 6

If there are no costs apparent at a particular site, why wouldn’t the individual stay there indefinitely?

Answer 6

The individual will probably have to load up and deliver food back to the group

Question 7

What is the ‘Marginal Value Theorem’?

Answer 7

Animals maximize their ‘marginal’ gains

• i.e. maximum slope of gain/time

Question 8

What does the marginal value theorem predict in practice?

Answer 8

The longer the travelling time to get to a patch, the longer the individual should stay in that patch.

Question 9

Why aren’t all animal specialist predators?

Answer 9

Can’t afford to be - they dont know when their next meal will show up

Question 10

What would be the optimum prey qualities?

Answer 10

Big enough for high energy content

Small enough for short handling time

Question 11

When searching for prey, when should a predator settle for a less profitable meal?

Answer 11

When the profit from eating type 2 > Time it would take to find a type 1 prey

Question 12

What predictions are there about being a specialist or a generalist predator (eater)?

Answer 12

1. Predator should eat just type 1 (specialise) or both 1 and 2 (generalise)
2. The decision to switch from one method to another depends on the abundance of type 1 (not type 2) prey
3. The switch from specialising to eating both prey, should be sudden

Question 13

How would foraging behaviour spread throughout a population?

Answer 13

Genetic variation

Parents who had the most effective behaviour could raise more surviving young

Over generations, genes for (or helping) behaviour were spread though population

Question 14

How might risk effect an animals foraging behaviour?

Answer 14

A site with less risk may end up giving maximum fitness benefits

• fitness benefits may not come soley from optimum nutrition or efficiency

Question 15

When should an individual choose a risk free patch?

Answer 15

When the threshold reward (minimum needed to survive) is less than the average payoff from that patch

Question 16

When should an individual chose a risk-prone patch?

Answer 16

When the threshold reward (minimum needed to survive) is higher than the average reward from patch

Question 17

What causes the difference in meerkat vs banded mongoose pup upbringing?

Answer 17

Meerkat environment = highly variable - their threshold values are higher than the average payoff when staying with one adult.

Banded mongooses = constant environment - their threshold is lower than the average payoff so can afford to stick with one adult