NetLogo Models Library:
IABM Textbook/chapter 4

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Wolf Sheep Simple 3

If you download the NetLogo application, this model is included. You can also Try running it in NetLogo Web

ACKNOWLEDGMENT

This model is from Chapter Four of the book "Introduction to Agent-Based Modeling: Modeling Natural, Social and Engineered Complex Systems with NetLogo", by Uri Wilensky & William Rand.

• Wilensky, U. & Rand, W. (2015). Introduction to Agent-Based Modeling: Modeling Natural, Social and Engineered Complex Systems with NetLogo. Cambridge, MA. MIT Press.

This model is in the IABM Textbook folder of the NetLogo Models Library. The model, as well as any updates to the model, can also be found on the textbook website: http://www.intro-to-abm.com/.

WHAT IS IT?

This is the third model in a set of five models that build toward a predator prey model of population dynamics. This third model gives the sheep the ability to eat grass and has the grass regrow over time.

It extends the model Wolf Sheep Simple 2.

HOW IT WORKS

The model creates a population of sheep that wander around the landscape. Moving around costs some energy, and when their energy gets too low, sheep die. However, sheep can eat grass in the environment to regain energy and the grass regrows over time.

HOW TO USE IT

Set the NUMBER-OF-SHEEP slider and press SETUP to create the initial population. You can also change the MOVEMENT-COST slider to affect the cost of movement for the sheep. The GRASS-REGROWTH-RATE slider affects how fast the grass grows back, while the ENERGY-GAIN-FROM-GRASS slider affects how much energy the sheep gain from eating the grass.

After this, press the GO button to make the sheep move around the landscape, and eat the grass.

THINGS TO NOTICE

Do all of the sheep die off at the same time? Is there any affect of location on how the sheep die off? You may have to slow down the speed of the model to observe this more closely.

At some point, sheep stop dying. Can you tell why?

THINGS TO TRY

What are the interactions between the various sliders of the model? For instance, can you balance the GRASS-REGROWTH-RATE, MOVEMENT-COST and ENERGY-GAIN-FROM-GRASS sliders such that the sheep never die off?

RELATED MODELS

The Wolf Sheep Predation Model in the Biology section of the NetLogo models library.

CREDITS AND REFERENCES

This model is a simplified version of:

• Wilensky, U. (1997). NetLogo Wolf Sheep Predation model. http://ccl.northwestern.edu/netlogo/models/WolfSheepPredation. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.

HOW TO CITE

This model is part of the textbook, “Introduction to Agent-Based Modeling: Modeling Natural, Social and Engineered Complex Systems with NetLogo.”

If you mention this model or the NetLogo software in a publication, we ask that you include the citations below.

For the model itself:

• Wilensky, U. (2007). NetLogo Wolf Sheep Simple 3 model. http://ccl.northwestern.edu/netlogo/models/WolfSheepSimple3. Center for Connected Learning and Computer-Based Modeling, Northwestern Institute on Complex Systems, Northwestern University, Evanston, IL.

Please cite the NetLogo software as:

• Wilensky, U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.

Please cite the textbook as:

• Wilensky, U. & Rand, W. (2015). Introduction to Agent-Based Modeling: Modeling Natural, Social and Engineered Complex Systems with NetLogo. Cambridge, MA. MIT Press.

COPYRIGHT AND LICENSE

Copyright 2007 Uri Wilensky.

This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License. To view a copy of this license, visit https://creativecommons.org/licenses/by-nc-sa/3.0/ or send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.

Commercial licenses are also available. To inquire about commercial licenses, please contact Uri Wilensky at uri@northwestern.edu.

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