The use and potential of pest-proof fencing for ecosystem restoration and fauna conservation in New Zealand

Abstract

The use of fences designed to exclude all exotic mammals from natural habitats is a recent conservation strategy being implemented on the main islands of New Zealand for ecosystem restoration and fauna conservation. As well as contributing to conservation outcomes, it has focused and galvanized public involvement in conservation. This chapter reviews the development of conservation fencing in New Zealand, the extent and distribution of conservation areas based on pest-proof fences, the experience of conservation managers with these fences and their current contribution. Between 1999 and 2009, 28 areas covering a total of 8,396 ha have been enclosed by 113 km of pest-proof fences and cleared of mammalian pests. Fenced areas have been located to exploit landscape features such as peninsulas, catchment boundaries, or fragments. Over this 10-year period, 63 translocations (mostly reintroductions) of 40 species have been made to these sites. This is similar to the number of translocations made to pest-free off-shore islands in New Zealand over the same time period. Notable species translocated to or managed within pest-proof fenced areas include: (1) several highly threatened, in which protection by fences is a key strategy to prevent extinction; (2) seabirds at new or existing nesting sites; and (3) several species reintroduced to the main islands of New Zealand after a substantial absence. The removal of pest mammals from the ecosystems enclosed by pest-proof fences is leading to changes in the composition of residual communities, and increasing the abundance of pest-sensitive populations as they are released from previous limits imposed by pest predation or herbivory. Failure to eradicate them or reinvasions of species such as mice Mus musculus are, however, an ongoing challenge.