Tawharanui

Tawharanui Open Sanctuary

Tawharanui Open Sanctuary is situated on the peninsula. It integrates the conservation of native species, farming, and public recreation, allowing visitors to get in touch with nature and the species within.

A pest proof fence was erected around the peninsula, supported by intensive pest eradication, to create the Open Sanctuary. Visitor education, including checking gear before visiting, and taking rubbish home, helps prevent pests from entering the sanctuary.

The Open Sanctuary is close to offshore islands acting as a stepping stone for native birds like the Kereru and Kaka. Bellbird colonised Tawharanui from Little Barrier Island in 2006 and are now widespread throughout the park.

The Open Sanctuary has meant that projects such as the reintroduction of brown kiwi, robin, whitehead, and forest and green geckos to Tawharanui could take place. Future reintroduction plans include pateke, kakariki, and threatened plants.

The Tawharanui Open Sanctuary Society Inc (TOSSI)

The Tawharanui Open Sanctuary Society Inc (TOSSI) was created to help the Open Sanctuary become a reality through fundraising and volunteer work. TOSSI works in partnership with the Auckland Regional Council on this project.

TOSSI fundraised for the pest proof fence through two campaigns. ‘The Art in the Woolshed' exhibited paintings, sculpture, and ceramics by local artists, and the ‘Get in Behind' campaign encouraged people to buy a metre of fence.

You can find further information about TOSSI at http://www.tossi.org.nz/

Why do we need open sanctuaries?

• Natural, healthy coastal environments are in short supply in New Zealand. In the Rodney District, where Tawharanui is located, more than 80% of remaining forests are less than 10 hectares in size, and just 1% of the original wetlands remain.
• Animal pests are causing our native animal and plant numbers to decline all over New Zealand. By removing them we can reverse this movement and create a pest free retreat. Doing this in a Regional Park means the public can access native species.

What animal pests were threats to the native wildlife of Tawharanui Open Sanctuary?

• The Tawharanui destroyer fleet comprised 10 species - feral cats, possums, rabbits, hedgehogs, mustelids (ferret, stoat, and weasel) and rodents (norway rat, ship rat and house mouse).
• The pests that have been successfully eradicated include ship rats, norway rats, cats, possums, weasels, stoats and ferrets.
• However there are still some pests that remain inside the Open Sanctuary: mice, rabbits and hedgehogs.

Why eradicate these pests?

• Because they have a deadly impact on the native species of plants and animals that do remain at Tawharanui as well as preventing the natural recovery of species such as grey faced petrel and reintroductions of lost species such as the brown kiwi and tuatara.
• Feral cats prey on eggs and chicks of many native species including NZ dotterel, variable oystercatcher and kereru. 
• Possums and rodents are predators of chicks and eggs of many native species. They also eat leaves, fruits, and new growth of many native plants reducing their availability for native animals. 
• Rabbits are a source of prey for cats and mustelids who when rabbit numbers are low, switch to other food sources (e.g. native species). They also browse new plantings. 
• Hedgehogs are a serious threat to native invertebrates, especially threatened or endangered species. It's estimated that hedgehogs could eat 0.825 kilograms of invertebrates per hectare, per night. 
• Mustelids are the most aggressive mammalian predators in New Zealand, feeding on native birds, insects and lizards. They are responsible for the death of 8 out of every 10 kiwi chicks in the wild.

How was the eradication undertaken?

• The first stage was the construction of a 2.5 kilometre pest proof fence, which was custom designed keep all of the Tawharanui pests out. The fence was completed in 2004.
• A one-off aerial bait drop was done on September 7th and October 21st 2004. This was extremely successful, eradicating ship rats, norway rats, cats, possums, weasels, stoats and ferrets. There are some pests that still remain inside the Open Sanctuary, including mice, rabbits and hedgehogs. 
• On going ground based techniques are continued, to prevent these pests. This includes surveillance inside the Open Sanctuary to detect pest incursion involves the tracking of tunnels, sand pads, trained predator sniffing dogs, and traps. Workers at Tawharanui Regional Park do occasionally detect pest incursion, but they work quickly to remove them.
• Advocating to park visitors, particularly campers, is a very important part of pest eradication. This involves notifying visitors of biosecurity precautions, checking for stowaway pests, and ensuring that all rubbish is taken away from the park.

Why was an aerial bait drop needed?

• Rodents have very small home ranges - about 10 square metres for mice. Based on the area of Tawharanui inside the predator proof fence, 57,000 bait stations would have been needed. Installing and servicing such an intensive ground system would have been unsustainable and unsafe, given the areas of inaccessible cliffs along Tawharanui's 9 kilometre coastline. Trapping alone generally fails to get rid of all rodents because trap-shy animals often avoid them.

Does the Open Sanctuary affect visitor use?

• No, the purpose of the Open Sanctuary is to enhance visitor experience by restoring coastal lowland landscape and providing a unique opportunity for visitors to experience native plants and animals in a pest free environment.
• The predator fence has a road gate, which opens as cars come towards it and then closes again. There are also three pedestrian gates along the fence.

What will pest eradication mean in the long run for Tawharanui Regional Park and the Open Sanctuary?

• A mainland sanctuary where existing native species can recover in the absence of animal pests but in the presence of human visitors.
• Eventually (at least 50 years away) the ARC envisages around 350 hectares, or two thirds of the park, will be re-established through natural regeneration and revegetation. This will create a representative range of natural communities that would have been present on the Tawharanui peninsula originally. These natural communities will include coastal lowland forest, dunelands, cliff, rocky and sandy shore communities and saline and freshwater wetlands. Most of this region of the park has already been fenced off from grazing.
• Imagine being able to camp and walk amongst native kiwi, brown teal, bellbirds and tuatara, and picnic in a puriri and nikau forest alive with bird song.