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Randyll Warehime

Class activity:

  • Simulation
  • Cooperative learning

Target audience:

  • BiologyLife Science, Environmental Studies



This lesson simulates possible effects of an introduced species on the population of native species. Although written with Hawaii in mind, it can be adapted to any geographic location or be used as is to introduce your students to a Hawaiian ecological problem. Hawaii has the greatest number of endangered species in the world. The introduction of species from outside the region has had, and continues to have, a tremendously negative impact on most all of the native species. In this simulation the introduced species has a broad niche (feeding capabilities) and all the native species very narrow niches (feeding capabilities). The opportunistic introduced "bird" quickly out-competes the three native species.

Background required of students: none

Preparation time: varies, depending on degree of adaptation to local environment.

Class time needed: 1 period

Materials needed:

  • Bag of salad macaroni, 1
  • Paper clips, 2 boxes
  • Bag of dry kidney beans, 1
  • Paper clips bent into a hook shape, 8 (species A)
  • Plastic spoons, 8 (species B)
  • Marking pen with an approximately 2mm x 2mm piece of magnet attached, 8 (species C)
  • Masking tape to tape the fingers (species D)
  • Yarn or masking tape to mark off feeding area
  • Plastic cups, approximately 32 (numbered, 1-8, for each population)
  • Student handout, 1/student
  • Copy of newspaper/magazine article on an introduced species, 1/student
  • Copies of "Counter's Data Sheet", 8/population counter:
Counter's Data Sheet
Species:Hook (A)Spoon (B)Magnet (C)Hand (D)
Number of pieces of food eaten by each bird in the population:

Procedure for Teacher:

  1. Prepare two large data tables to be filled in by the data recorder that are visible to the class (see Student Handout). Title one of the tables "Amount of Food Eaten" , Blacken all Round 1 cells and Rounds 2 and 3 cells for species D. Title the other table "Population", Enter "0" for the population of Species D for both rounds 1 and 2.

  2. Clear a large area of the room. Mark off the feeding area (long and narrow, approximately 2' x 25') with yarn or tape.

  3. Assign roles: 1 data recorder; 0, 4, or 8 food counters; birds in populations A, B, C, D. You may want the "birds" to count their own food or if you have a large class, have designated counters. Try to have 4-6 birds assigned to each population; it doesn't have to be the same for each since natural populations are not all the same.

  4. Have birds and food counters go to separate areas of the room where the "Counter's Data Sheets", beaks and cups are located for that species.

  5. Have counters tell the data recorder the number of birds in each population (Population D is zero, they won't be feeding until the third round).

  6. While students are reading over the rules of the simulation, distribute the food (paper clips, macaroni, and beans) in the feeding area. Food doesn't need to be a limiting factor, although I have found out that the paper clips seem to be easiest to pick up and so I would suggest it be limited.

  7. Conduct the simulation (see Student Handout). Depending on the data, determine how long you want the simulation to go on. While the first round is going, instruct the introduced birds that they will use the hand that they don't write with and that they are to tape their hand so that they can only use their thumb and forefingers (tape three fingers down). During the simulation, there are many things to notice:

    • Do the birds move within their habitat?
    • The native birds seem to be adapted for a particular food source: spoon beaks:beans, hook beaks: macaroni, and magnet beaks: paper clips. There is not too much competition.
    • A species may run out of food before the minute is over. This could mean their food source suffered from drought or other natural phenomena.
    • When the introduced species enter the simulation, they tend to wipe out the food in the area.
    • The introduced species are generalists, whereas the native species are not. Competition for food increases.
    • A native species may become extinct, it may decrease or increase in population, or it may be able to remain stable despite the introduced species.
    • The introduced species tends to increase at the expense of the native species.

  8. Debrief activity orally and/or with the use of the questions on the student handout.

Method of Evaluation:

  • Observation
  • Oral discussion
  • Written work


Research introduced species in your area. Search newspapers for articles relating to species introduction in your area.



The Hawaiian Islands began to form 25 to 2 million years ago when underwater volcanoes finally rose above the surface of the sea. There were no people here until about 300 to 500 A. D. When the first Polynesians from the South Pacific arrived they found many plants and animals already here. How did they get here? Well, birds flew here, other creatures floated on the ocean or swam, plant seeds and some insects were blown here by the wind or hitched a ride on the birds.

For over a million years these plants and animals lived with no people. During that million or more years, they changed (evolved) so that there was not too much competition for food between different types of animals, for example, Hawaiian Honeycreepers (types of birds) evolved from one species to at least thirteen different species; some drank nectar, some ate seeds, and some ate insects. Everybody in the food web was happy, relatively speaking.

All of these plants and animals that were here before people came here are called native species. There were many snails and insects (but no mosquitoes nor cockroaches); a few kinds of freshwater fish (like the o'opu); no frogs, toads, lizards; many kinds of birds; and the only native mammal on land was the bat (no mongoose, cats or dogs).

The ancient Hawaiians brought plants and animals with them from the South Pacific, including bananas, rats, dogs, pigs, taro and fleas. Later, beginning in the 1700's, people from other parts of the world began to come to Hawaii bringing even more plants and animals, like pineapple, tilapia, cattle, cats, mongooses, and mosquitoes. All of these plants and animals that are not native are called introduced species (or foreign species or exotic species).


Most of you will represent a different type of bird, some of you will be native species and some will be introduced species. You will be trying to get food with your "beak" in order to survive. If your species gets the most food, your population will increase. If your species gets the least food, your population will decrease. Some of you might choose to be food counters or the data recorder.

BEFORE THE SIMULATION: Define "native species" and "introduced species".



  1. Native Animals:
    • Use only your mouth part to pick up food, or die (be disqualified)!
    • You can pick up any type of food. Remember, you want to get a lot of food.
    • Pick up only one piece of food at a time and put it in the cup. You can use your free hand to take the food off your mouth part and put it in the cup.
    • If your cup falls over, you lose all that food.
    • Feed for one minute only.
  2. Native Animals: Give your cup to your counter.
  3. Counter:
    • Count and record the number of pieces of food each animal ate.
    • Add up the total pieces of food eaten by that species.
    • Give data sheet to the recorder.
  4. Recorder:
    • Record number of pieces of food eaten for each population.
    • Mark an "X" over the lowest and circle the highest.
  5. Teacher:
    • Remove the animal with the lowest number of food eaten from its population.
    • Add one animal to the population that ate the most.
  6. Recorder: Write the number of animals in each population.


  1. Repeat steps 1-6 one more time - only native animals feeding.


  1. Introduced species enter the feeding area.
  2. Repeat steps 1-6 three or more times - native and introduced animals feeding.


  1. Copy the class data of the populations during the eight rounds. Round (Year) Population A Population B Population C Population D 1 0 2 0 3 4 5 6 7 8
  2. What characteristics, or behavior, made each bird species unique from the other bird species?
  3. How did the birds' characteristics or behaviors affect their eating habits? Were they able to eat any type of food? Why or why not?
  4. If this activity is an example of how native birds lived before and after the arrival of humans to the islands, which rounds (years) represent the "before" period? The "after" period?
  5. What happened to the native populations after the arrival of the introduced species?
  6. For these native populations, was the arrival of an introduced species harmful or helpful? Why?
  7. Use the data in the data table to make a line graph of Population Vs Round (year). Put all four populations on the same graph using a different color line for each population.
  8. Write a one-page reaction paper: "The Effect of Introduced Species on Native Species": What did the simulation show (use your answers to questions 1 thru 8 to help you)? Summarize the main ideas in the article. How does the simulation we did in class relate to the ideas in the article?

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