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Wolf Sheep Predation (System Dynamics)

Run Wolf Sheep Predation (System Dynamics) in your browser uses NetLogo 4.1 requires Java 5 or higher (system requirements) Note: If you download the NetLogo application, every model in the Models Library (besides the Community Models) is included. If you have trouble running this model in your browser, you may wish to download the application instead.

WHAT IS IT?

This is a model of a simple predator-prey ecosystem. It uses the System Dynamics Modeler to implement the Lotka-Volterra equations.

The Lotka-Volterra equations are a pair of first order, non-linear, differential equations that describe the dynamics of biological systems in which two species interact.

HOW IT WORKS

At each step, the value of the SHEEP-BIRTHS flow is added to SHEEP stock, and the value of the SHEEP-DEATHS flow is subtracted from the SHEEP stock. The same is done for the WOLVES stock. Each flow is calculated in terms of the variables, and stocks that are linked to it.

HOW TO USE IT

1. Press the SETUP button.
2. Press the GO button to run the model.
3. View the SHEEP and WOLVES monitors for the current value of those populations.
4. View the plot to observe the populations changing over time.

THINGS TO NOTICE

What happens when the sheep population increases? And the wolves? Why do you think this is the case?

THINGS TO TRY

Use the System Dynamics Modeler to change the values of the variables in the system, such as SHEEP-BIRTH-RATE and PREDATOR-EFFICIENCY.

NETLOGO FEATURES

This model uses the System Dynamics Modeler to simulate the Lotka-Volterra equations.

RELATED MODELS

Wolf-Sheep Predation
Wolf-Sheep Predation (docked)

CREDITS AND REFERENCES

Lotka, A.J. (1956). Elements of Mathematical Biology. New York: Dover.

"Lotka-Volterra equation". From Wikipedia. http://en.wikipedia.org/wiki/Lotka-Volterra_equation

Eric W. Weisstein. "Lotka-Volterra Equations." From MathWorld. http://mathworld.wolfram.com/Lotka-VolterraEquations.html

HOW TO CITE

If you mention this model in an academic publication, we ask that you include these citations for the model itself and for the NetLogo software:
- Wilensky, U. (2005). NetLogo Wolf Sheep Predation (System Dynamics) model. http://ccl.northwestern.edu/netlogo/models/WolfSheepPredation(SystemDynamics). Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.
- Wilensky, U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.

In other publications, please use:
- Copyright 2005 Uri Wilensky. All rights reserved. See http://ccl.northwestern.edu/netlogo/models/WolfSheepPredation(SystemDynamics) for terms of use.

COPYRIGHT NOTICE

Copyright 2005 Uri Wilensky. All rights reserved.

Permission to use, modify or redistribute this model is hereby granted, provided that both of the following requirements are followed:
a) this copyright notice is included.
b) this model will not be redistributed for profit without permission from Uri Wilensky. Contact Uri Wilensky for appropriate licenses for redistribution for profit.

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