Adaptive Foraging Behavior

1. Adaptive Foraging Behavior ZOL 313 May 28, 2008

2. Adaptive Foraging Behavior Objectives: 1. Become familiar with some adaptive foraging strategies that animals can use to help them locate, select, capture, and consume food. 2. Be able to generate hypotheses and predictions about the adaptive value of foraging behaviors. 3. Understand how to use Optimality Theory to study adaptive foraging. ZOL 313 May 28, 2008

3. Locating food Capturing Food Consuming Food Selecting Food

4. Locating Food • Develop a search image Search image:

5. Locating Food • Develop a search image Hypothesis: Prediction:

6. Locating Food 2. Follow cues/exploit signals Hypothesis: Kestrels find areas of high vole concentration by Prediction:

7. Locating Food 3. Get help from others Example: M. panamica

8. Locating Food 3. Get help from others: Information centers: Prediction 1: Birds waiting in the colony should Prediction 2: Naïve birds should

9. Locating Food 3. Get help from others Do raven roosts serve as information centers?

10. Selecting Food Do animals select food optimally? Optimality Theory:

11. Selecting Food Do animals select food optimally? • Example: Howler monkey foraging • When foraging, howler monkeys: • Were more likely to feed on less common tree species. • Preferred smaller, scarcer new leaves over the more abundant, larger mature leaves. • Frequently only ate the petiole and dropped the larger leaf blade. Does this seem like optimal foraging? Why or why not? What types of costs and/or benefits might make this behavior optimal?

12. Selecting Food Do animals select food optimally? Example: Oystercatchers selecting mussels Fitness cost: Fitness benefit: Model A: Birds should focus on the largest mussels Model B: Birds should avoid the very largest mussels

13. Selecting Food Do animals select food optimally? Hypothesis: Prediction:

14. Selecting Food Do animals select food optimally? Responding to predation risk Hypothesis: Prediction:

15. Selecting Food Do animals select food optimally? Example:

16. Capturing Food 1. Get the prey to come to you Hypothesis: Prediction: But, is this correlation the result of site productivity?

17. Capturing Food 2. Use an uncommon strategy Frequency-dependent selection: Allows 2 different strategies to coexist in a population. Example: Right and left jawed African cichlids

18. Capturing Food 3. Get help from others Example: Colonial web-building spiders

19. Capturing Food 3. Get help from others Example:

20. Capturing Food 4. Know when to quit Example: Optimal quitting time in starlings: Optimality model A: Starlings should always carry their maximum prey load Optimality model B: Starlings that carry a large prey load pay a metabolic and a time cost

21. Consuming Food 1. Optimal food preparation Example: From what height should the crows drop large whelks to minimize the costs of flying higher and/or having to drop the whelk again?

22. Consuming Food 2. Why do humans eat dirt? Hypothesis 1: Hypothesis 2: Comparative Method ->Is this an example of convergent or divergent evolution?

23. Consuming Food 3. Is human use of spices adaptive? Hypothesis: What would you predict about the relative amount of spices in traditional recipes from: Vegetable dishes vs. meat dishes? Hot/tropical countries vs. cold/snowy countries?