Mathematical models of wildlife management by contraception

Because of some disadvantages with traditional culling by baiting or trapping for population control, contraception is being considered again by many wildlife managers. Mathematical analysis is necessary for practical use of contraception in wildlife management. In this paper, we have proposed several steady-state models of contraception and simple culling. Major conclusions are drawn from theoretical analysis. (1) In the absence of competitive reproductive interference by sterile individuals, contraception is as effective as traditional simple culling in controlling small animals and could be better in controlling medium or large-sized animals. (2) Higher percentages of sterile individuals are required for controlling small animals than for controlling large animals. (3) More contraception effort is needed for controlling small areas or animals with high dispersal ability than for large areas or animals with low dispersal ability. There are no obvious advantages to contraception over simple culling in reducing immigration in steady-state models. (4) Better control effect could be achieved by contraception than by simple culling when the competitive reproductive interference is taken into account.