Owls, Mice and Seeds
In order to better understand how people and ecosystems influence one another, let's pause and consider how any population of a living organism influences the populations of other organisms within an ecosystem.
Have white board, recorder and dry-erase markers ready to count and keep track of the changing populations at the end of each round. This lesson works best with 2-3 field groups joined together (make sure at least 2 instructors know the rules), and it can apply to either ecosystems or watersheds themes. Begin with a brief review of producers, consumers, and decomposers and then focus for a moment on herbivores, omnivores and carnivores and how those groupings translate into predator-prey relationships. In this activity, you'll need one predator (owl) for every 3 or 4 prey (mice) and every 600 seeds (each child can be 100 seeds). Inform kids that their goal will be to STAY whatever organism they begin as, but that they may well become others in the multiple rounds of the activity.
Explain that you will have the mice turn their backs (since they are down in holes and cannot see where the wind blows the seeds). Then, you'll send the seeds out on the wind (“seeds, disperse!”). After a few seconds, you'll release the mice to find food (“mice, forage!”) and then just a few seconds after, the owls will go hunting for dinner (“owls, hunt!”). Seeds have until you say, "Seeds, plant!" to find a suitable spot where they think the mice may not find them and eat them. Once the seeds have planted they cannot move again until you call the group in for the end of the round. Owls MUST wait until you release them to hunt. Give them time to try to catch a mouse, but they cannot catch a mouse that already has food … that mouse is thus hiding in its hole, eating its seeds.
Use your designated call-back sound to bring all players back. They must stand in groups according to what they were at the beginning of the round. Then, ask which mice found a seed bunch before an owl got it. They will remain as successful mice in the next round. Seeds that were eaten also become mice, (since they provided food energy for a mouse instead of growing into a plant). Did any mice get eaten? They become owls. (Owls that caught a mouse remain as successful owls.) Did any mice starve in spite of not being caught by an owl? Did any owls starve? All starving animals become seeds. Then, did any seeds succeed in not getting eaten? They remain as successful seeds, planted and growing more seeds.
You can also add in pollutants that rise through the food chain, and ecologists working to reintroduce locally extinct populations (if owls all die, it helps to do this to continue the game). This can also lead to some powerful discussions later.
Play five or six rounds of this ~ the kids will not tire of it ~ then get them in a circle, nice and tired and ready to focus. Review how the populations changed over time using the big graph white board (see below for an additional challenge for more advanced groups). Chances are good that the populations will go up and down and in fact follow each other in rises and falls in population.
Remember these kids were just running around for 30-45min playing a game, for most not even realizing the importance of the owls eating the mice, and that the mice need seeds to survive.
Once in a circle, have students turn to the person next to them and discuss at least three things that are realistic about this activity? Come back together and have some students share what they came up with. Next, give them a moment to turn to someone on the other side and discuss three things about the activity that are unrealistic. Again, discuss, but this time, when someone shares something they saw as not realistic, ask the group if anyone can think of it may be realistic, but just indirect (i.e. “an owl doesn’t really turn into a seed if it dies” is true, but it is decomposed and then returned to the soil and then taken by a plant someday which will make seeds). This is a great chance to reiterate, or introduce, interconnections. Was it hard or easy to be a ___? Who here succeeded in remaining the same organism throughout all of the rounds? Why do you think the populations went up and down so much? This is called Dynamic equilibrium. (ooh, big word!) Do the seeds influence the mouse population? Do the mice influence the seed population? Do the owls (and so on, through all of the interaction. In what other ways do plants and animals influence each other's success in an ecosystem? How about people? Are we part of that system?
For added challenge, give the students the numbers from the game and have them graph it themselves on the graph page in the journal. They will need guidance with this most likely. You can also give them a chance to write or create a food web in their journals, then move around and see what they have created
Select a spot that has trees but not too much uneven ground or downed timber. Give clear boundaries and remind kids that they won't really be eaten, so be careful! Make sure all know to stop the chase and return to you whenever they hear the return signal.
Here's a one page handout you can use to collect data if you run OMS at a school.