Optimal Foraging

Question 1

What is optimality logic?

Answer 1

Selection will favour animals that forage most efficiently

Question 2

What observations were taken of Northwestern Crows?

Answer 2

Always select large whelks (3.5-4.4cm)

They drop them from around 5m onto rocks to break them open

Keep dropping a whelk until it breaks

Question 3

What predictions were made for Northwestern Crows?

Answer 3

• large whelks should break more easily at 5m than small whelks
• whelks dropped < 5m should be less likely to break and whelks dropped at > 5m should be no more likely to break
• the chances of a whelk breaking should be independent of the number of times its dropped

Question 4

What further insights can be made when a hypothesis based on cost benefit logic is found to be incorrect?

Answer 4

1) the animal may not have been well ‘designed’ by selection

2) the observations may have been inappropriate

3) an important factor may have been omitted from the model

4) the assumptions may not have been valid

Question 6

How do oystercatchers select what to eat?

Answer 6

Predicted to select large mussels that yield most food

But when mussels that can be opened are considered, the optimum size is 50mm