Handout for Laboratory 13, Vertebrate Zoology 03051
Animal Behavior and Ecology: Deer and Bear Simulations
Text (Hickman et al., 7th ed.), Ch. 5
We will be engaged in two role-playing simulations this week. The first involves deer population numbers over several generations, and the other involves a bear population and the local carrying capacity.
DEER: natural populations vary year by year and do not remain constant. Neither does the environment in which organisms live. To demonstrate these factors, we will"act" as deers in an ecosystem with fluctuating availability of food, water, and shelter.
how to play: count off by fours, with"ones" as the first generation of deer. Deer and habitats (the rest of the students) line up several yards apart with their backs to each other. Each deer and each habitat will then decide what they will emphasize for that breeding season (year). Those deer seeking food or those habitats with plenty of food will hold their hands over their stomachs. Those deer/habitats seeking/supplying water will put their hands over their mouth, and those deer/habitats seeking/supplying shelter will hold their hands over their head. Once selected, these cannot be changed for that breeding season. On the count of three, deer and habitat turn around to face each other and the deer race over, with their hands in position, to meet up with habitats supplying their needs. Those deer who do not match up with a habitat die and become part of the habitat for the next breeding season. Successful deer and the habitat they matched up with both become deers for the next round. Your instructor will graph the results of deer numbers vs. breeding seasons (try for twelve or more generations).
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# of |
1 |
2 |
3 |
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5 |
6 |
7 |
8 |
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12 |
13 |
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deer |
years (breeding cycles) |
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What does the appearance of the graph tell you? Do populations and environments stay constant in nature?
BEAR: carrying capacity is the given number of organisms that a given area can support. We will"act" as bears to show how individual bears are likely to survive or perish in a setting with limited food supplies.
how to play: Previous research based on Arizona bears indicate the following average diet for a ten day period:
20 pounds of nuts (25% of diet), 20 pounds of berries (25%), 20 pounds of plants (25%), 12 pounds of insects (15%), and 8 pounds of meat (10%), or 80 pounds total. We will use"food chips" (labeled milk bottle tops) as markers of this food (instructor note: use all of the chips available, unless your lab is fifteen or under--at which point scale down accordingly). The"food" will be scattered in the field, with students/bears lining around it in a circle. Not all bears can compete equally. One student chosen at random will be crippled from a fight with another bear and have to hop on one leg. Another"bear" will be blinded (blindfolded) from porcupine quills. A third bear will be a mother with cubs, and so needs twice as much food for all to survive. In order to eat, bears will grab ONE piece of food at a time and PLACE (not throw) it back at their home spot ("cave"). There is no stealing from home caves, but controlled bumping in getting food is allowed! At the signal, bears will start their"ten day forage." When the food is gone (it won't take long!), students will then individually total up the amount of food that they have collected. Those who did not collect at least 80 pounds starve to death.
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Category |
# of low-point chips |
# of high point chips |
Total pounds of food |
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Nuts (N) |
N-10: |
N-20: |
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Berries (B) |
B-10: |
B-20: |
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Plants (P) |
P-10: |
P-20: |
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Insects (I) |
I-6: |
I-12: |
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Meat (M) |
M-4: |
M-8: |
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Total pounds of food for all categories: |
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Questions:
Was all of the food collected equally? Why or why not?
How did the handicapped bears fare?
Did the mother bear feed herself or the cubs first? Why?
Did all of the bears survive?
How balanced was the diet of those bears that survived?
How many bears would have survived if the food was divided equally? Is that likely to happen in nature?
What is the relationship between population size and carrying capacity?
If the weather is appropriate, finish up along the HVCC Nature Trail. Look for signs of vertebrates, e.g., footprints, sightings. How does the nature trail look different in the spring compared to the fall, e.g., vegetation, light availability to ground plants?
|main page| |background| |03028: Physiology| |03048: Anatomy|
|03050: Invertebrate Zoology| |03051: Vertebrate Zoology| |03074: Economic Botany|
Please send comments and questions to: cronewil@hvcc.edu
Copyright 1999, 2000 by Wilson Crone
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This web page last updated on April 24, 2000