Foraging

Question 1

Zero-one rule:

Answer 1

a type is either always attacked upon encounter or always ignored upon encounter.

Question 2

What are the three preidictions of the prey model?

Answer 2

1. Zero-One Rule
2. Ranking by Prey Profitability (types are ranked by the ratio of energy per attack, to the handling time per attack, the profitability)
3. Independence of Inclusion from Encounter Rate: inclusion of a type does not depend on its own encounter rate, but only by its profitability.

Question 3

What are the three chracteristics of gain functions?

Answer 3

1. The net energy gain when zero is spent in a patch is zero
2. The function is at least initially increasing.
3. The gain function is eventually negatively accellerated.

Question 4

Explain the marginal-value theorem:

Answer 4

A rate maximizing forager will choose the residence time for each patch type so that the marginal rate of gain at the time of leaving equals the long-term average rate of energy intake in the habitat.

Question 5

What kind of foraging does better capture mosquito anemotaxis?

Answer 5

Many foragers do not totally consume each prey item and some authors (Cook and Cockrell, Giller, Sih) have used marginal value theorme to explain this. Foragers such as Notonect and Myrmeleon, which suck the contents of their victims, can be shown by interruption experiments to experience diminishing returns with sucking time. This has led to the assumption that these predators treat their prey like patches. It might be similar to McNair model of overlapping encounters.

Question 6

What similar (but non identical) conclusio do travel restriction models of foraging reach?

Answer 6

For short travel times, superiority of prey hinger on energy per unit (true) handling time. For long travel times, superior prey are those of higher energy, regardless of handling time (Schoener model, Orians and Pearson model)

Question 7

What ar the two recognition constraints models:

Answer 7

1) recognition time models
2) imperfect resemblance models

Question 8

What are three ways in which appearence types might be related to profitability types?

Answer 8

1. There may be a simple one-to-one relationship between appearance and profitability (perfect resemblance scenario)
2. Appearence may not be informative: prey are equally likely to have profitability p1 or p2 regardless of their appearance.
3. Appearencemay give partial information about profitability.