Management of animal and plant pests in New Zealand - patterns of control and monitoring by regional agencies

Abstract

Context. Significant resources are spent annually in New Zealand controlling pests to mitigate impacts on native biodiversity and agricultural production, but there are few reliable estimates of the benefits. Concerns have been expressed about inconsistent monitoring methodologies, differing frequencies and intensities of control across organisations, and poor definition of desired outcomes. Aims. To conduct and report on a survey of animal and plant pest control and monitoring by regional agencies, to identify issues with current practice and to provide advice on improvements. Methods. We surveyed 15 regional agencies in New Zealand about the pest control and associated monitoring undertaken during 2005–08. We recorded the pests targeted, the control work done and its operational details, any result and/or outcome monitoring conducted, and estimated costs. Key results. About 21% of the NZ$20 million expenditure on pest control was for monitoring. Excluding compliance (62%), monitoring changes in pest populations accounted for 31% of the total monitoring expenditure, whereas only 7% was spent measuring response in the resource that was supposedly being protected. The most common monitoring design (71%) comprised a single treatment area with no non-treatment area, in which only results were monitored. Only three programs (4%) had both treatment and non-treatment areas and both results and outcome monitoring. Conclusions. Such limited outcome monitoring constrains severely the ability of regional and local authorities to provide robust justification for their pest management activities and expenditures. Implications. Improved outcome monitoring requires better design of and additional resources for monitoring programs, improved institutional/political support for long-term programs, and better definition of long-term outcomes and objectives for pest management.

Multiple threats, or multiplying the threats? Interactions between invasive predators and other ecological disturbances

“…The global cost of monitoring and controlling these predators is in the order of hundreds of millions, if not billions, of dollars annually (e.g. Clayton and Cowan, 2010;Gong et al, 2009).…”

Density-impact functions for terrestrial vertebrate pests and indigenous biota: Guidelines for conservation managers

“…In contrast, relatively few studies have quantified the responses of indigenous biota (both species and ecological processes) in natural ecosystems. This may be because insufficient resources are allocated for monitoring (Clayton and Cowan, 2010;Reddiex and Forsyth, 2006) or because techniques are inadequate (de Bello et al, 2010). Baxter et al (2008) developed a theoretical model that examined the cost-effectiveness of controlling pest predators, and concluded that suppression of predator abundance to a 'pre-determined limit' (or threshold) can be a more cost-effective strategy than eradication.…”

The use and value of citizen science data in New Zealand

“…The potential exists in New Zealand for community data to contribute to larger monitoring programmes given current shortfalls in agency-led monitoring (Clayton & Cowan 2010). For example, limited outcome monitoring being conducted on possum (Trichosurus vulpecula) control operations by resource management agencies (Clayton & Cowan 2010) could be supplemented by data from community groups, as large numbers of groups trap possums and other predators on council-owned land (Peters et al 2015).…”