By the end of this activity, students will:

1) understand the necessity of large families in some wild populations.

2) participate in an activity that relates food supply to population.

3) understand the nature of competition between predators.

4) evaluate the effect of increasing and decreasing food supplies on animal

populations.

Science

1) Knows how variation of organisms within a species increases the chance of survival of the species, and how the great diversity of species on Earth increases the chance of survival of life in the event of major global changes.

2) Knows that the transfer of energy (e.g., through the consumption of food) is essential to all living organisms.

3) Knows how the amount of life an environment can support is limited by the availability of matter and energy and the ability of the ecosystem to

recycle materials.

4) Establishes relationships based on evidence and logical argument (e.g., provides causes for effects).

1) copy of the program "The Living Edens: Etosha"

2) popcorn

3) tape measure

Two periods. Period one: discuss the characteristics of the organisms and begin the first simulation. Period two: discuss the results of the first simulation and conduct the simulation with the predators. Additional time may be needed to watch the video components.

Background Information

The predator-prey relationship is complex and is affected greatly by environmental conditions. At times of abundant food supplies, predators breed to produce litters where most individuals survive and increase the pressure on the prey populations. As more of the prey are taken, the food supply declines which results in starvation and reduced health for the remaining animals. A cyclical pattern emerges of increasing population then decreasing population. This simulation will illustrate the cyclical pattern, which can then be compared to the populations of animals in your area. As more factors are introduced, students will better understand the complex interactions found in a food web.

Procedure

1) View the section of jackals hunting for doves (located at 5:00 into the program).

2) Discuss how many doves it would take to feed a jackal for a day, a week and a year. Students should be guided into the 3 to 5 a day range. Discuss how many jackals it would take to feed a cheetah for the same period of time. Students may research animal characteristics on the Internet for data to use in the discussion.

3) Discuss the frequency and number of young in a litter of doves, jackal and cheetah.

4) Measure a 30-meter (100-foot) section outside in the schoolyard. Randomly throw handfuls of the popcorn through the area. There should be lots of popcorn available at the start.

5) Select and line up five students on one side of the area to begin the simulation. Explain to students that they are jackals and must collect 5 pieces of popcorn as they cross the measured area in order to "stay alive." The retrieved popcorn is placed in a container at the finish line and is removed from the available resources.

6) The simulation is repeated. After the second trip, any jackal that survives then "reproduces" and selects another student to join the simulation. The simulation is repeated until "starvation" begins to reduce the population. Additional popcorn, in varying amounts, can be added after a trial to represent the food production in good and poor years.

7) During a second simulation, competing predators are introduced. A cheetah must pick up 10 pieces of popcorn to survive. Each of the jackals should have a piece of cloth hanging from their belt (similar to that found in flag football). A cheetah can eliminate a jackal by removing the flag.

8) Students will graph the results of the simulation with a bar graph showing the number of each animal at the end of a time period. Students will write a description of the simulation explaining the effect of increased food supplies, decreased food supplies and competition on predator populations. Students will explain what characteristics in a population help some animals survive.

African Wildlife Resource

http://www.awr.net/

This site has a database of information on a variety of wildlife.

Students will be assessed through their participation in the activity and the discussion preceding it. The graph and data charts should be evaluated for completeness and a rubric developed for scoring the explanation of the graph.

1. Additional variables may be introduced to the model by adding items to represent other food sources or other animals. The class can decide the living requirements for the additional animals. Predators may be allowed to eliminate competitor species.