W2: Foraging Behavior

Question 1

Foraging

Answer 1

finding, selecting, catching and consuming food; includes herbivory and carnivory

Question 2

Optimal Foraging Theory

Answer 2

Basic assumption is that individuals animals forage so as to maximize their fitness

Question 3

Optimal Foraging Models

Answer 3

predict optimal foraging behavior given a specified currency (i.e. energy) and constraints (i.e. predation risk)

Question 4

Models

Answer 4

mathematical/graphical formalization of hypotheses

Question 5

Currency

Answer 5

the units in which fitness, or a surrogate for fitness (i.e. calores) is measured

Question 6

Patch

Answer 6

an area with a relatively high density of prey

Question 7

What is the optimality/adaptationist approach?

Answer 7

1) Construct a mathematical model of a problem an animal faces
2) Generate quantitative prediction
3) Test predictions against the behavior of the animals
4) Modify the model to take into account additional variables and constraints
5) MODIFY AGAIN if required
6) STOP when the model predicts the behavior of the animal

Question 8

Why is selective foraging a good variable to test in models?

Answer 8

It focuses on energy consumption which is required for growth and reproduction.

Question 9

Central Place Forager

Answer 9

Nest in one location and forage in another

Question 10

What are some key elements of starlings foraging on leatherjackets?

Answer 10

1) travel time to and from the nest
2) time required to search for prey
3) ability to catch prey declines as the bill fills up
4) optimal number of leatherjacks starlings can carry

Question 11

Marginal Value Theorem

Answer 11

When travel times are larger, optimal load size increases
Assumptions:
1) animals are maximizing energy intake
2) energy was the appropriate currency
3) proper constraints identified
4) animals are a central place forager

Question 12

Prey Size Model Variables

Answer 12

E(1) = energy in food 1
T(h1) = handling time of food 1
E(2) = energy on food 2
T(h2) = handling time of food 2

Question 13

Profitability of Prey Size Model

Answer 13

E/T(h)
energy per unit time

E(1)/T(h1) > E(2)/T(h2)

Question 14

Predictions of the Prey Size Model

Answer 14

1) the predator should either just each prey 1 (specialist) or eat both prey 1 and prey 2 (generalist)
2) the decision to specialize depends on the abundance of the big prey not the small prey
3) the switch from eating only prey 1 to becoming a generalist will occur suddenly. Only when both sides of the equation are equal will it not matter what the predator eats.

Question 15

How should a predator chose whether to eat a big mussel or a small mussel?

Answer 15

-it should eat the big mussel whenever they are encountered
-it should only eat the small mussel when: the gain from eating the small muscle is greater than the gain of rejecting it and spending time searching for the more profitable larger muscle OR E(2)/T(h2) > E(1)/[T(s1)+T(h1)]
Eating the smaller muscle depends on the abundance of large muscles.

Question 16

Kleptoparasitism

Answer 16

a form of feeding in which one animal takes prey or other food from another that has caught, collected, or otherwise prepared the food, including stored food

Question 17

Frequency Dependent Selection

Answer 17

Fitness of on phenotype is a function of its frequency relative to the other phenotype.
** It leads to an equilibrium frequency of hunters and thieves.