TOSSI – Animal pest control at Tāwharanui

Tāwharanui Open Sanctuary is home to many rare and endangered native species. It is a sanctuary not just because it has a pest-proof fence, but also because it has a small army of people looking after it, many of whom are volunteers for the Tāwharanui Open Sanctuary Society Inc (TOSSI).

The pest-proof fence was completed in 2004, making this the first open sanctuary integrating conservation, recreation and farming in New Zealand. Korimako (bellbirds) had re-established by 2005 and kākā by 2008. Other reintroduced bird species include whitehead, North Island Brown kiwi, North Islanad robin, pāteke, kākāriki, tīeke (saddelback) and takahē. Most of these species have thrived, with translocations to other sites to avoid overcrowding and help with gene pool mixing.

Seabirds nesting at Tāwharanui include: grey-faced, diving and Cook’s petrels, fluttering shearwater, kororā (little penguin) and white-fronted tern. New Zealand dotterel nest (precariously) on the foreshore. Banded rail, Australasian bittern and spotless crake also inhabit the sanctuary.

The non-avian gems include elegant, forest and Duvaucel’s geckos, shore skinks, giant kōkopu and wētāpunga, all of which are vulnerable to mammalian predators.

The pest-proof fence has been a huge success in restricting predator access to the Sanctuary.

However, it has to be checked weekly for damage and each end stops above the high-tide line, leaving opportunity for pest access. Then there are the predators that swim and those that hide in vehicles. It is wonderful that the sanctuary is also a public reserve, popular for picnicking, walking, biking, camping, swimming and surfing; but this adds to the challenge of pest control. Volunteers help Auckland Council rangers and pest control contractors keep on top of the pests.

More than 240 people have been invloved with regular volunteering for TOSSI over the years.

Thousands more have been involved with planting days. Currently there are about 30 volunteers doing animal pest control work and a similar number doing plant propagation, planting and weed control.

On the animal pest side, volunteers are checking and resetting traps, refilling bait stations, checking ink cards in monitoring tunnels, servicing trail cameras, reviewing camera images, loading catch data into a national database (TrapNZ), checking the pest-proof fence and conducting rabbit surveys. Lots of variety, for the fit and not-so-fit, and all for a great cause.

Success can be measured in various ways:
• 225,000 people visited the Sanctuary last year, many coming to see their first takahē or tīeke, to spot kiwi at night, or just to hear the chorus of bird song
• invading predators seen in the sanctuary are targeted and generally caught quickly
• the annual kiwi count has progressively increased from 5 calls/hour in 2012 to 15.5 calls/hour in 2025
• on the wider Tāwharanui Peninsula, after 14 years of active community pest control led by Takatu LandCare, kākā are thriving, flocks of kerurū are seen and kiwi, spilling from the sanctuary, are settling at sites as far away as Buckletons Bay

Interested in volunteering at Tawharanui? Contact secretary@tossi.org.nz