Student Activities

Animal Populations Up and Down

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Grade Level:
Middle School: Sixth Grade through Eighth Grade
Subject:
Science

Background

Animal populations have natural cycles. Those cycles are frequently influenced by human pressures. Students will see animal populations grow and decline, and learn more about predator prey adaptations that classify animals. These activities introduces the basic population dynamic concepts with simplified fluctuations. 

Materials

a. 1 lb bag of dry brown beans (or other colored beans)

b. 1 lb bag of white beans

c. plastic locking sandwich or snack bags, or cups to store beans

Procedure

NATURAL CYCLES ACTIVITY

1. Pair or group students

2. Give each group 2 brown beans (predators) and 10 white beans (prey) and a supply of white and brown beans to draw from. (It is easiest to "pair up" beans to count and track them)

3. Explain to the students:

a. In a healthy natural situation there are more prey animals than predators

b. That this is not a realistic situation because many factors affect animal populations and this activity only represent one aspect of a population cycle.

4. The teacher will tell students when to "cycle"

A) For each cycle, 

i. Predators:

1. Each predator will remove 2 prey animals (put 2 white beans for each predator back in draw pile). (After the cycle, the teacher may lead students to discuss availability of predators' food/shelter/space)

2. If a predator gets 2 prey, each predator PAIR will produce one offspring (add 1 brown bean from draw pile for each PAIR of predators)

ii. Prey:

1. After the cycle, the teacher may lead students to discuss availability of prey food/shelter/space

2. Each remaining prey PAIR will produce 2 offspring (add 2 white beans for each PAIR of remaining prey)

B) The teacher will repeat the instructions for the students to do a cycle, at least three times.

i. Note: at the end of the first cycle there will be 3 predators and 12 prey

ii. Note: at the end of the second cycle there will be 4 predators and 12 prey

iii. Note: at the end of the third cycle there will be 5 predators and 8 prey

iv. At this point the teacher may stop and ask the students what has happened.

The teacher can lead a discussion asking what is going to happen:

1. To the predator population (starve, closer together so more disease, fight for food/space/shelter, wander out of area, reproduce less)

2. To the prey population (more food, shelter, space, may reproduce more, farther apart so less chance of disease spreading)

5. The inverse: When predators are over hunted, or die.

A) For each cycle,

i. Predators:

1. Each predator will remove 2 prey animals (put 2 white beans for each predator back in draw pile). (After the cycle, the teacher may lead students to discuss availability of predators' food/shelter/space)

2. Situation: Although the predators get enough food and reproduce, their offspring do not live to an age where they can reproduce, so no new predators are added. (Teachers can ask the students what may cause the young not to live long enough to reproduce? i.e. weather, genetic defect, hunting, disease, etc)

ii. Prey:

1. After the cycle, the teacher may lead students to discuss availability of prey food/shelter/space

2. Each remaining prey PAIR will produce 2 offspring (add 2 white beans for each PAIR of remaining prey)

b. The teacher will repeat the instructions for the students to do a cycle, at least two times.

i. Note: there will always only be two predators taking 4 prey

ii. Note: at the end of the first cycle there will be 12 prey

iii. Note: at the end of the second cycle there will be 16 prey

iv. At this point the teacher may stop and ask the students what has happened.

The teacher can lead a discussion asking what is going to happen:

1. To the predator population (grow old and die, get hunted, etc)

2. To the prey population (less food, shelter, space, may reproduce less, closer together so more chance of disease spreading)

6. Lead a discussion about what they saw happen in the activity, and remind them that there are many factors that affect populations

 

OTHER INFLUENCES ON ANIMAL POPULATIONS ACTIVITY

1. Local Influences: Habitat quality (see Qualitative vs Quantitative activity)

2. Outside influeunces: Global Warming/Climate Change

a. Ocean life: more CO2 means more acidic ocean water

b. Insects: Behavior (dispersal of aphids) is affected by CO2 levels

c. Birds: Chickadees prefer caterpillars that eat leaves with lower tannins, which are associated with lower CO2 levels.

Additional Resources

http://www.npca.org/assets/pdf/NPCA-Wildlife-text_only_version.pdf

http://www.npca.org/assets/pdf/00-NPCA-Wildlife.pdf

https://www.nps.gov/training/tel/Guides/climate_change_brochure2_08072008.pdf

http://www.slideshare.net/NationalWildlife/nwf-wildlife-warmingworldreportweb-16247032

http://www.npca.org/assets/pdf/unnatural_disaster_2.pdf

 

 

 

 

 

Materials

Download Attitudes toward Animals Survey

Download Setup for Beans

Download Qualitative & Quantitative Worksheet

Last updated: January 11, 2016