Optimizing disturbance management for wildlife protection: the enforcement allocation problem

To ensure public compliance with regulations designed to protect wildlife, many protected areas need to be patrolled. However, there have been few attempts to determine how to deploy enforcement effort to get the best return on investment. This is particularly complex where repeated enforcement visits may result in diminishing returns on investment. Straightforward quantitative methods to solve such problems are not available to conservation practitioners. We use structured decision-making to find the most cost-effective allocation of patrol effort among sites with a limited budget. We use the case study of declining migratory shorebirds in Moreton Bay, Australia, to determine where and when Marine Park personnel could reduce disturbance using two different scenarios: (i) where a fixed subset of sites is chosen for management each year and (ii) where different sites are visited during each patrol. The goal is to maximize the number of undisturbed birds for a given budget. We discover that by prioritizing enforcement based on cost-effectiveness, it is possible to avoid inefficient allocation of resources. Indeed, 90% of the maximum possible benefit can be achieved with only 25% of the total available budget. Visiting a range of enforcement sites at varying rates yields a greater return on investment than visiting only a fixed number of sites. Assuming an exponential reduction in disturbance from enforcement, the greatest benefit can be achieved by patrolling many sites a small number of times. Assuming a linear reduction in disturbance from enforcement, repeatedly patrolling a small number of sites where return on investment is high is best. If we only prioritize sites where wildlife is disturbed most often, or where abundance is greatest, we will not achieve an optimal solution. The choice of patrol location and frequency is not a trivial problem, and prudent investment can substantially improve conservation outcomes.Synthesis and applications. Our research demonstrates a straightforward objective method for allocating enforcement effort while accounting for diminishing returns on investment over multiple visits to the same sites. Our method is transferable to many other enforcement problems, and provides solutions that are cost-effective and easily communicable to managers.