Z404 Prey with two predator dynamic
Model name
Z404 Prey with two predator dynamic
Original author(s)
Hartmut Bossel
References and/or links for original model
Format of original model
Vensim
Converted by
Francesco Benvenuti
Date submitted
20/04/2012
Purpose
This model allows to explore population dynamics of Prey and of two predators.
Often a single prey population is the source of food for several competing predators (e.g. mice as prey of foxes and birds of prey). The Model provide a reliable intuitive assessment of long-term development of a prey population and that of two predator relying on it as a food source. The model assists in recognizing development trends inherent in the system structure even if in reality a variety of other factors determine the development and may cause it to proceed on a somewhat different path.
Description
In this system with a single prey population and two predator populations predator A and predator B there exist again two predator-prey linkages (prey encounters predator A, and prey encounters predator B). These linkages correspond to those in the normal predator-prey system. Predator A and predator B have specific energy consumption rate a and energy consumption rate b. The prey population has (relative) growth rate prey. The rates of increase of the predator populations (predator A gain, and predator B gain) are determined by (relative) prey gain predator a and prey gain predator b. The prey loss is a function of (relative) loss caused by predator a and loss caused by predator b.
However, a small disadvantage of predator A (insignificantly higher energy consumption rate a) suffices to cause this population to disappear after some time. Thereafter an undamped oscillation develops for prey and the remaining predator B (undamped because of unrestricted carrying capacity)
Model size indicators
Stocks and flows
Simile diagram
Simile equations
Predator A loss = Predator_A*Energy_consumption_rate_A
Predator B gain = Prey_gain_Predator_B*Prey_encounters_predator_B
Predator B loss = Predator_B*Energy_consumption__Rate_B
Predator A gain = prey_gain__predator_A*prey_encounters__predator_A
Prey gain = Growth_rate_prey*Prey
prey loss = loss_caused_by_predator_A*prey_encounters__predator_A + loss_caused_by_predator_B*Prey_encounters_predator_B
Prey encounters predator B = Predator_B*Prey
prey encounters predator A = Predator_A*Prey
Files
The model and associated files are listed at the bottom of this page. The model may be provided in more than one format (e.g. as Vensim .mld and Simile .sml files).
Notes on the conversion process
Extra information on original model
In the long run, the behavior of the system corresponds to that of the predator-prey system in model Z401(Predator and unlimited prey)