The logistic model is useful in describing populations which exhibit exponential growth at small populations but who live in environments which enforce an upper limit on population size. With this model populations move toward the carrying capacity K as time goes on regardless of the initial population. Even a very tiny population will eventually reach the carrying capacity.
Extinction never occurs under the logistic model.
If the population we are studying is a population of game animals, it is important to include the effect of hunting in the model. Having a model of this sort can help wildlife managers set scientifically sound hunting limits. The exercises below assume a Stella model has been built with an intrinsic growth rate a of 10 percent and a carrying capacity K of 1000. These exercises are designed to show that even a very small change in the level of hunting can have a dramatic effect in the long term health of the population. If we leave behind the idea of hunting for the time being, there is a second modification to the logistic model which increases the model's realism and usefulness.