An analysis of the form of density dependence in a simulation model of a seasonal breeder undergoing control

A simple deterministic simulation model was constructed to examine compensatory mechanisms of a seasonal breeder following population reduction, with a view to determining the optimum time of year to apply such control. Data collected from studies on the European rabbit, Oryctolagus cuniculus, were used in the model. The compensatory mechanisms considered were a reduction in mortality, an increase in fecundity, an increase in the length of the breeding season, and a combination of reduced mortality and increased fecundity. Any degree of seasonality in either mortality or breeding led to an optimum time of year to apply a control policy, if some level of compensation occurred. In the absence of such compensation, there was no optimal time to perform population control. If such control is unbiased toward either sex then the optimum time of control is usually at the beginning of the breeding season (January). The optimum time for a male biased control policy was during the non-breeding season (November to January). Female biased control led to a more complex situation where the optimum was dependent upon the type of compensation and the degree of such compensation. This work has shown that the presence and form of compensatory mechanisms (density-dependence) may produce or adjust the optimum timing of control in populations which have either seasonal variation in mortality or fecundity.