Optimal Foraging

First, the instructor will explain the activity. The foragers will hunt for prey represented by pinto beans in four buckets of rice with varying prey densities. Without knowing what these densities are, foragers must obtain as many prey items as possible in as little time as possible.

In this experiment, the experimental hypothesis could be that foragers will catch the most prey in the higher prey density bucket and also spend the most time foraging there. The null hypothesis would then be that foragers will catch an equal number of prey in each bucket and that foragers will spend an equal amount of time foraging in each patch. To begin the foraging activity, record the names and role of each participant at the top of the student data collection sheet.

Before starting the experiment, the forager is allowed to become familiar with the foraging process. The forager should kneel or sit in front of the average bucket. Once the timer says start, the forager may begin looking for the pinto beans representing the prey.

The forager can spend as much time as they like foraging in this bucket. Once a prey item is located, the forager must signal that one has been found and place the prey in the cup next to the bucket. Once they believe they have acquired most of the prey in the patch, they should tell the timer to stop the time and the practice round is over.

The forager should sit or kneel in front of bucket A.The timer must be ready to start the stopwatch. The recorder should be ready to record the time each prey item is located in addition to the time that the forager arrived at and left each bucket. When they are ready, the timer starts the stopwatch and says start and the forager begins foraging.

The stopwatch will run through the rest of the round for buckets B and C.As the forager signals finding pinto beans and places them in the cup next to the bucket, the timer should tell the recorder the time. The recorder can then write the time in the student data collection sheet. Once the forager has decided to move on to the next bucket, they should tell the timer done and begin moving to the next patch.

The recorder should record the time the forager left and the time they arrived at bucket B in the student data collection sheet. Repeat the same procedure for buckets B and C.Once the forager has completed the activity, it is time for the next forager to begin using the same procedure. Before performing any data analysis, review the data collection sheet and compile your individual data for captured prey, foraging time, and travel time for each bucket in your student calculations table.

After this, calculate your individual capture rate for each bucket by dividing the number of prey captured by the sum of the foraging time and travel time and record these values in your table. To calculate your Giving-Up-Time or a GUT for each bucket, subtract the time that the last prey item was acquired from the time you left the bucket. Next, calculate the mean GUT for your foraging group and record the values in your table.

Finally, calculate your scaled GUT for each bucket by dividing the bucket GUT by your group's mean GUT. The scaled GUT will allow class data to be pooled later on without differences in individual foragers skewing the data. Now the instructor will compile the data into the classroom spreadsheet.

Now plot the following bar graph. First plot the average number of prey collected in each bucket. On the x-axis, A represents the low prey density bucket, B represents the medium prey density bucket, and C represents the high prey density bucket.

The y-axis shows the number of prey items caught. Next, plot the graph of the class average scaled GUT. Again, the x-axis represents the buckets with varying levels of prey density.

The y-axis shows the values for the average scaled GUT. Finally, plot the graph of the average time spent foraging in each bucket. Now review the Marginal Value Theorem or MVT from the concepts video that describes how foragers should optimally utilize resources and move between patches in their habitat.

Now look at the three graphs that you generated from your class data. Do the graphs conform to the predictions of MVT? Do any of the graphs disagree with the theorem?