The Tongariro Forest Conservation Area contains a nationally important and relatively large population of northern brown kiwi. Tongariro Forest consists of about 21,000 hectares of logged and unlogged podocarp forest. Historically Tongariro Forest probably contained thousands of kiwi. However, recent surveys suggest there may be less than 500 remaining, and large tracts of the forest have no kiwi at all.

Kiwi were given further protection in the Tongariro Forest Kiwi Sanctuary in 2003, with the gazettal of Tongariro Forest (as well as Erua & Rangataua Forests) as a Controlled Dog Area and the introduction of avian aversion training for hunting dogs run by local contractor Jim Pottinger. Dogs are one of the main threats to adult kiwi.

Stoats are considered the key threat to kiwi as they kill most of the kiwi chicks produced in each breeding season, preventing recruitment of new individuals into the population. Without intervention to reduce the effects of stoat predation, the Tongariro Forest kiwi are likely to become extinct in a decade or two.

As for many other kiwi populations around the country, survival of this population in the long term depends on finding methods of stoat control that can be applied sustainably on a very large scale.

Objectives

The aim of the Tongariro Forest Kiwi Sanctuary is to achieve and maintain a representative sample of 100+ pairs of North Island Brown Kiwi by 2010. It will achieve this through Operation Nest Egg and monitoring and further investigation as to the effect of large scale 1080 on pest dynamics.

Progress to date: Operation Nest Egg (ONE)

Tongariro Forest kiwi management has focused on the ‘Operation Nest Egg’ method. ONE is the process where eggs are taken from the wild to be raised in captivity where they are safe from stoats, then released back to the wild when they reach a size that they can defend themselves. This technique provides an effective safeguard against local extinction, and is being undertaken at a number of sites around the country where large scale stoat control cannot be achieved. It is a good way to increase populations quickly. For Tongariro Forest kiwi, ONE is done in collaboration with the National Kiwi Recovery Trust captive rearing team at Rainbow Springs. However ONE is a neutral management toll. It benefits monitored kiwi pairs and does not benefit other parts of the ecosystem. For this reason other options are being trialled as well.

The successfully hatched kiwi chicks are transferred to Warrenheip (a predator free enclosure in the Waikato which is privately owned by David and Juliette Wallace) from Rainbow Springs two-three weeks after hatching, once they are feeding well and thought to be healthy at a weight of approximately 300g. Using Warrenheip as a crèche site in which to raise the chicks prior to their return to the wild has enabled the kiwi chicks to grow in a semi-natural environment. Most chicks take approximately six months at Warrenheip to grow to a release weight of 1200 grams – at this point they are believed to be big enough to defend themselves from stoats and are released back into the forest.

A 1080 drop in 2001 gave the local kiwi population a brief respite from stoats for the 2001/02 breeding season. However, the Operation Nest Egg programme has been an effective tool used to prop up the local kiwi population in the Tongariro Forest since then.

The first Tongariro ONE juvenile kiwi was released into Tongariro Forest in 1997. This male (named ‘Te Aukaha’) is now breeding with another ONE juvenile (‘Koha’). To date almost 100 ONE juvenile kiwi have been released into Tongariro Forest from up to 30 kiwi pairs.

Wild Kiwi Monitoring

The Tongariro Forest Kiwi Sanctuary (TFKS) are currently monitoring 26 wild kiwi pairs and eight ONE kiwi pairs. For the 2005/2006 season and for the next two seasons wild chicks will be allowed to hatch in the forest to assess the effectiveness of the 1080 drop in September 2006.

Predator Trapping

Predator trapping occurred from August 1994 until April 1998 to determine predator abundance in the forest and seasonal changes in rodent and predator populations. The trapping numbers were then increased, and combined with brodifacoum poisoning (bait stations) in an attempt to protect kiwi chicks and juveniles. The predator control was discontinued in April 1998 as it was felt that the trapping was not providing any significant benefit for kiwi. Instead TFKS will assess the effectiveness of a large scale 1080n drop by monitoring benefits for kiwi chick survival, fantail nesting success and protected plant health.

Partnership

Teamwork between Massey University, National Kiwi Recovery Trust, Warrenheip, Ngati Hikairo, the Bank of New Zealand Kiwi Save the Kiwi Trust, Tongariro Natural History society and the Department of Conservation remains a major strength of the project. All of these groups are working together cooperatively, allowing more to be achieved than would have resulted from each group working individually.