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# Optimal Foraging

Optimal Foraging

## Learning Objectives

At the end of this lab, students should know...

#### What is foraging?

Foraging is the process of searching for resources including food, shelter, and mates.

#### What does Optimal Foraging Theory model?

Optimal Foraging Theory models the circumstances in which an organism meets the optimum balance between expending energy to forage and acquiring resources from foraging.

#### How are resources spread out within a habitat?

Generally, resources are not spread out evenly in a habitat. Resources are usually contained in “patches” that foragers must move between.

#### What are the five predictions of Marginal Value Theorem?

First, foragers should capture more prey in patches with high prey density. Second, foragers should spend more time foraging in high prey density patches. Third, foragers should have a higher prey capture rate in dense environments. Fourth, foragers will spend more time foraging in dense environments. Finally, a forager should leave a patch when the capture rate has declined to the average rate of all patches.

#### How do you calculate the Giving Up Time (GUT)?

To calculate the GUT, subtract the time that the final prey item was acquired from the time the forager leaves the patch.

## List of Materials

• 5-gallon bucket
4
• Small plastic cups
4
• Rice (15-30 Lbs/bucket; can add more rice to make foraging rigorous
60-120 Lbs
• Dry Black-eyed peas (1/4 C ~ 70-80 beans)
0.5 Lbs
• Stopwatch
1
• Clipboard
1
• Table 1 and 2- print outs
1
• Marker
1

## Lab Prep

1. Setting up the Foraging Habitat Patches
• Print a student data collection sheet for each student to record data. NOTE: Students will work in groups of three for this activity. For any given round, one student will forage, one student will record data and another student will run the stopwatch.
• Choose a location for the foraging activity to take place. An open field is ideal for this activity but a hallway will suffice provided another location is not available.
• Label four five-gallon buckets as A, B, C and Average.
• Fill each bucket with 15 to 30 pounds of rice. Make sure the amount of rice is the same in each bucket.
• For the bucket labeled A mix in six pinto beans. This represents the low prey density.
• For the bucket labeled B mix in 16 pinto beans. This represents the medium prey density.
• For the bucket labeled C mix in 26 pinto beans. This represents the high prey density.
• Finally, for the bucket labeled average mix in 16 pinto beans. This represents the average prey density.
• To distribute the buckets, place buckets A and average at the start of the foraging area five paces apart from each other.
• Walk 25 paces away from the first two buckets and place bucket C.
• Then walk 10 paces to the right or left of C and place the final bucket, B.
• Place an empty cup next to each bucket – these will stay with the bucket, and the instructor must mix the pinto beans back into the rice after each forager has finished the course. NOTE: The average bucket should always be placed at the start but for variety or convenience the buckets can be arranged in different ways or at different distances or prey items and numbers can be varied.

#### Tags

JoVE Lab Lab: 30 Prep

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