Below is a model meant to simulate the number of Black-throated Blue Warblers on the study plot at Hubbard Brook, based on food availability, predator abundance, and the strength of density dependence operating during the breeding season. The initial values are set to the average conditions observed during the period 1986-1999. First, run the model with those parameters and then adjust the sliders along the bottom and run the model again (see instructions below).

If you cannot see the image below you will need to install Java software, available here.


1. Press the setup button.
2. Press the go button to run the model.
3. View the warbler monitor for the current value of the population.
4. View the plot to observe the population size changing over time.

5. Adjust the initial-warblers, density-dependence, food, and predator sliders, run the model again and see what happens.


Learning module developed by K. Langin, H. Sofaer and S. Sillett for the Hubbard Brook Research Foundation (2009).