Taking the Last Stand
Pest eradication and the creation of Sanctuaries
by Judy Gilbert
 

The strong focus on island eradication projects in northern NZ this year is an indication of the growing commitment by community groups, DoC, ARC, and private landowners to creating sanctuaries that aim to sustain and enhance NZ’s biodiversity. Already in the Hauraki Gulf many islands including Hauturu (Little Barrier), Cuvier, the Mokohinaus, Tiritiri Matangi, Motuihue, Rakino, and Motuora are pest free. These sanctuaries provide a safe haven for native species and create the potential for wildlife populations to move naturally and be translocated between the islands of the Gulf. Commonly these projects are initiated with aerial bait drops to remove rodents and ground based programmes to remove species such as cats and rabbits.

Close to home, Glenfern Sanctuary in Port Fitzroy undertook two aerial rodent bait drops as part of a larger eradication programme to remove rats, mice, rabbits, and feral cats within the 230 hectare sanctuary this winter. This sanctuary area is made up of private landowners and a DoC scenic reserve. At the same time this was carried out three of Ngati Rehua’s Broken Island chain had drops undertaken by the ARC. A team of people is always required to carry out any hand-baiting around buildings and places where it is unsuitable for a helicopter drop.

Together with Motu Kaikoura Island and the chain of 24 islands that make up the Grey, Nelson and Motuhaku groups (where an eradication programme was initiated in 2008), this brings a significant area of small islands off the Great Barrier coast closer towards a pest free status. In the proposed DoC Conservation Management Strategy Rakitu (Arid Island) is also listed for future pest eradication. These island chains are very significant to the restoration of our once abundant seabird colonies which have been decimated by rats.

Earlier in the winter the 3,850 ha Motutapu and Rangitoto Islands were helicopter baited by DoC for rats, mice, rabbits, cats, stoats, and hedge-hogs. The ‘mop-up’ of remaining pests following the drops is currently underway using a range of methods. A team of 58 people were involved in this eradication. Some non target effects occur to species like pukeko and ducks but their numbers quickly recover in the absence of animal pests. On Tiritiri Matangi following the removal of rats a 500% increase in invertebrates was measured within the first few years. There will always be some risk but with careful management the few losses are hugely outweighed by the subsequent gain.

The Hauraki Gulf Biosecurity Plan is also nearing completion with a focus of maintaining a high standard of Biosecurity throughout the Gulf and keeping the many islands of the Gulf that are now pest free with that status. Both DoC and ARC have initiated campaigns over the last few summers to heighten public awareness to this issue through a range of measures including advertisements in boating magazines, a DoC/ARC programme entitled Our Treasure Islands, announcements on boating radio stations, and new signage at main boating ramps throughout the region.

There has been a particular focus on the boating community to keep vessels pest free when boating in the Gulf. All major transport providers are currently involved with DoC and ARC to put Biosecurity measures in place on vessels. There are over 100 pest free islands in NZ and the risk of reinvasion is always present – it’s not a matter of if, but when. Monitoring for reinvasion is an on-going process as is having a thorough and effective response to a known or suspected re-invasion. More often than not, this is a single animal and in over 86% of cases has been eliminated fairly quickly.

A bit further afield during this winter the eastern Bay of Islands group made up of Motuarohia (Roberton Island), Moturua, Motukiekie, Okahu, Waewaetorea, Urupukapuka, Poroporo and all the associated islets and rock stacks initiated an eradication. This is aimed at eradicating rats and mice with a follow up to cull any remaining stoats. Known as Project ‘Island Song’ this community initiative involved the Guardians of the Bay of Islands, iwi, and DoC.

It is estimated that there are currently around 4000 community groups involved in conservation in NZ – these range from a simple project involving replanting a stream edge to the fully fenced 22,000 hectare sanctuary created at Cape Kidnappers on private land. Cape Kidnappers Sanctuary area includes a well visited gannet colony, golf course and luxury lodge. To date they have translocated nine locally extinct native species into the sanctuary area, including kiwi.

In response to the increasing public involvement in threatened species and sanctuary management, government funding was granted in 2005 to Landcare Research for the purposes of looking at increasing the effectiveness of flagship sanctuaries. The Sanctuaries of NZ forum was formed from interested groups who share information, discuss and debate practices, hear current research, and network ideas. Landcare Research takes the opportunity with the groups to research social sustainability, monitor draft success measures with-in sanctuaries, undertake research that helps sanctuary management, maintain a sanctuariesnz.org website, and runs an annual workshop.

Over 40 sanctuaries (see Map below) have participated to date from all over the country. Many of these sanctuaries were sparked off following the establishment of six DoC “Mainland Islands” between 1995-1997. They were sited in ecologically significant areas with the primary focus of learning how to carry out ecological restoration in a mainland setting. A great deal has been learned, to the benefit of the sanctuaries that followed, by the addressing of management questions through rigorous trials and experiments, intensive monitoring and evaluation, and the development of standardised systems and processes. New poisons and equipment have been trialled, 50+ studies written up and published, and reporting practices refined. Operation Ark sites to protect critically threatened species and DoC kiwi zones have been established since.
Within the over 40 sanctuaries that have been established there are three main types of management - 15% are predator-proof fenced (do eradication and surveillance) such as at Glenfern , 8% have a fence planned, and 77% are not fenced (do sustained control) such as at Windy Hill. Most of the sanctuaries have been established with the goal of sustaining and improving biodiversity.

Map of the location of pest-eradicated sanctuaries on mainland New Zealand and its immediate offshore islands.

The sanctuary sites are :
• Experimentally restoring New Zealand ecosystems to indigenous dominance and full species complement
• ‘New’, inspiring and innovative initiatives that have galvanised communities to local conservation.
• Projects that aim to:
– Control or eradicate a broad suite of pests
– Reintroduce missing species
– Manage a permanent and substantial risk of reinvasion by pests
– Involve local communities

The combined sanctuaries area totals 63,638 ha, made up of 56,270 ha (88%) of Public land and 7368 ha (12%) of private (including Maori) land. Added to this are the pest-free islands which total 36,482 ha.

These areas make up just .24% of the NZ land area. This tiny percentage represents our best integrated efforts at holding on to the native species that are iconic to our country.

The creation of such sanctuaries, on islands as well as in protected areas on the mainland, are essential because elsewhere in NZ there is nothing to stop the overall loss of biodiversity and more species to extinction. Five years after the launch of the NZ Biodiversity Strategy in 2000 a review indicated that it was proving difficult to slow loss of habitat and protect species from predation. The target goals set in 2000 were not being reached and that the creation of sanctuaries on both private and public land with good habitat and reduced or eliminated pests were the key.

On Great Barrier we have a number of sanctuaries that have developed over the last ten years – besides the well established Glenfern and Windy Hill Rosalie Bay Sanctuaries there is the Mohunga Peninsula Sanctuary, the Schooner Bay Weed project, the Awana Catchment Trust, the Medlands Beachcare, and the new Katherine Bay Restoration Trust. These projects are the working models of community based conservation and pave the way for the possibility of Great Barrier Island becoming the biggest pest-eradicated sanctuary of them all.