Predator-Prey Simulation with Mice and Owls
Introduction
Animals spend much of their time looking for and consuming food. Many omnivores and carnivores obtain their protein by hunting other animals and killing them. The “hunters” are referred to as predators and the animal that is being “hunted” are known as the “prey.”
You will be working with owls as the predator and mice as the prey. Owls are excellent predators, feeding on not only mice but also rabbits, squirrels, rats, shrews, small birds, fish and even insects. In nature, owls and mice are often found living in forests. The forest in this lab will be referred to as “Hoot Woods.”
You will be simulating 18 generations of owls and mice. The mice can be eaten and the owls can starve. Any surviving mice and owls can reproduce. However, Hoot Woods can only sustain 400 mice. For this simulation, each surviving mouse produces 1 offspring. So, for each new generation, the remaining mouse population doubles. For example, if 3 mice remain after generation 1, then there will be 6 mice to begin generation 2.
In order to survive, each owl must catch at least 3 mice each generation. If an owl does not catch 3 mice, it will starve. If an owl catches 3 mice during a generation, it produces 1 owlet. So, if an owl catches 8 mice during generation 1, then it makes 2 owlets. Generation 2 then begins with 1 mama and 2 owlets.
To begin each new generation, there must be at least 3 mice and 1 owl. If at any time you drop below these numbers, new mice and/or owls will migrate into “Hoot Woods.”
1. Based on the introduction, what do you think that the purpose of this lab might be. Write a complete sentence below.
Materials
Masking tape, meter stick, 400 squares of construction paper, 1 paper owl
Instructions
A. Using masking tape, mark off a square approximately 50 cm on each side. This square represents Hoot Woods where
both the mice and owls live.
B. Place 3 mice randomly into “Hoot Woods.”
C. From a height of about 30 cm, drop the owl onto Hoot Woods trying to hit as many mice as possible in 1 drop. If the
owl touches any part of a mouse, then this is a catch. (As you make more owls, drop them 1 at a time into the woods.)
D. Remove and count the number of mice that were caught by each owl and record in data table 1.
E. To complete generation 1 add new owls and mice as described in the introduction.
F. Begin generation 2 and continue steps B – E until you complete 18 generations. Be certain to remove the caught
mice and the starved owls each time, and to add new mice and owls appropriately.
Data Table 1.
Generation / # mice to start / # owls to start / # mice caught / # owls starved / # surviving mice + babies / # surviving owls + babies1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
2. Create a single graph. On the graph:
Graph the # of generations of mice vs. the population size of mice. Use brown.
Graph the # of generations of owls vs. the population size of owls. Use orange.
Using the following terms, label both graphs accordingly: growth, carrying capacity, predator, prey.
3. In order for both species to survive, which population had to increase in size first. Explain why.
4. Scenario A: If all of the owls were hunted to extinction, predict what might happen to the mouse population in Hoot
Woods. (Recall that the maximum # of mice that Hoot Woods can sustain is 400.)
5. Explain why the population of mice cannot go over 400? Name several factors that determine this limit to the size
of the mouse population.
6. Scenario B: Some people dump their cats when they are no longer wanted. If these cats find their way to Hoot
Woods and begin eat the mice in order to survive, predict what might happen to all 3 populations. Be certain to
include the terms competition and invasive/non-native species.