This depends on many factors such as population size, density and reproductive biology of the target species, type of contraceptive and method to deliver contraceptives. The effect of contraception on population size also depends on whether a population is isolated or open to immigration and emigration. Feedback processes, such as increased recruitment, survival rates, and immigration, may compensate for reductions in reproductive output caused by fertility control. Recent mathematical models, developed to compare contraception and lethal control to manage wildlife, suggest that in some contexts, integrating fertility control with culling could be more efficient then culling alone.