Name______Date______Group______#______
Population game - Interactions among living things
Directions:
1. Mark off an area 0.5 meter square (about 70 cm by 70 cm). This is where the hawks and the field mice live.
2. Stand back for a toss (one small step).
3. Drop 3 field mice in the area.
4· Throw a hawk in the area. Try to make it land on as many field mice as possible. A touched mouse is a caught mouse.
5. Pick up the hawk card. Remove any captured mice and enter the new tallies.
6. Double the remaining field mice each new generation
7. In order to reproduce, the hawk must land on 3 mice. For every three mice captured each hawk has one offspring. For example, if the hawk catches seven mice, three hawks enter the next generation - the original eagle and two offspring.
If a hawk captures none or one mouse it dies and if it captures only two mice it lives but does not reproduce. If no hawk survives another hawk moves in.
In order to keep track of hawks, for each hawk tossed, record mice captured and new hawks as -1, 0 or +n where n is multiple of three for mice captures. If the hawk captures 7 mice, for that hawk two new hawks are added to the next generation plus the original hawk.
8. Record each generation. Play for 20 generations.
10. Analyze the date graphically. Mice and hawk population (Y axis), each generation (X axis). Plot the mouse population and the hawk population side by side on the same graph. Use a different color for each.
By generation 5 the hawk might catch enough mice to survive and reproduce.
Between generation 9 and 11, the population will probably crash near zero. Cycle should repeat itself through 18-20 generations.
QUESTIONS
1. Which population reaches higher numbers? Why is this?
2. As the field mice population gets bigger, what happens to the population of hawks? Does this happen right away or is there a lag?
3· Notice that as the hawk population rises, the field mouse population falls. Why? Does this happen right away or is there a lag?
4· Does the eagle population stay high for long? Why or why not?
5· Why do populations rise and fall?
6. What do predators do to the size of a population?
7· What is a predator?
8. What is a prey?
9· What is a predator- prey relationship?
10. Do the prey and predator populations change slowly (flat lines on the graph) or rapidly (steep lines on the graph)?
11. How do you think other natural factors like diseases, hunting, floods, fires, extreme cold etc. might affect the population?