Estimating the Costs of Protecting Native Species from Invasive Animal Pests in New South Wales,Australia

Invasive animal pests reduce crop and livestock output, require management and control measures, and threaten native plants, animals and their habitat. The agricultural and management costs are often directly measurable. But the costs to protect threatened native plants and animals are harder to assess. The Rural Lands Protection Boards were the government agency in New South Wales that managed invasive animals. An analysis of their decisions provided the opportunity to estimate the costs of protecting native species. The number of native plants and animals threatened by invasive pests was modelled against the expenditure, area, pest abundance, climate and location of 38 Board districts. There was a strong negative relationship between the number of threatened native species and Board expenditure. This relationship was interpreted to estimate the marginal cost of protecting a threatened native species, the downward shift in the supply curve necessary to protect all threatened native species, and the gains from the shift in the form of cost savings in the continued protection of non-threatened native species. These results value some of the costs that invasive animal pests impose on the environment.