Eagle Population Lab

Background: Population growth is affected by different environmental factors such as: climate, food, water, pollution, disease, and competition between other species. These factors can limit a population’s growth. The different types of limiting factors can be density dependent or density independent.

Purpose: The purpose of this lab is to better understand what affects population growth.

Materials: Male eagle, Female eagle, lake grid, 300 popcorn kernels (fish)

Procedure:

Scenario 1 (table 1)

  1. Place the lake grid on your desk.
  2. Put 150 popcorn kernels (fish) on the lake grid.
  3. Drop the male eagle onto the lake grid. Remove any fish that the eagle touched when it landed. Repeat (each eagle hunts twice a day). Count the number of fish caught and record this on your table in the day 1 column and the row marked “# of fish caught by male”
  4. Repeat step 3 for the female eagle.
  5. Repeat each day until you have reached 9 days or the eagles die. The eagles die if the pair does not catch 8 fish in 3 days.

Scenario 2: drought (table 2)

  1. Repeat steps 1-5, except this time a drought kills 38 fish. Start with 112 fish.

Scenario 3:spring (table 3)

  1. Repeat steps 1-5, except this time the fish are spawning. Start with 300 fish.

Scenario 4: pollution (table 4)

  1. Repeat steps 1-5, except this time the lake is polluted and 112 fish die. Start with 38 fish.

Scenario 5: babies (table 5)

  1. Repeat steps 1-5 with 150 fish, except this time the eagles have 2 babies. They must catch 10 fish in a 3 day period.

Analysis questions:

  1. Graph each scenario on a single line graph that shows the total number of fish caught each day. Be sure to title your graph, label the x and y axis, and include a key. Hint: you will need 5 lines
  2. Which scenarios showed density dependent limiting factors? Why?
  3. Which scenarios showed density independent limiting factors? Why?
  4. Ospreys also eat fish. Imagine a pair of ospreys immigrate to the lake. What effect, if any, might the competition have on the eagle population?
  5. Explain how a climate change might or might not indirectly affect the eagle population.
  6. If humans began fishing the lake, how do you think the eagle population would be affected? Why?

Conclusion: Which scenarios had the largest effect on the eagle population in this simulation? Why? Do you think this simulation was an accurate portrayal of a real ecosystem? Explain.