Pests

Kiore

Tiritiri was a prime location for the restoration project because it was relatively pest free, that is free of unnatural predators eg cats, possums, rodents or mustelids. There was only one mammalian predator the kiore that did not pose much of a threat to our native birds. However, at certain times there was a population explosion with records of 200 kiore per hectare in the grass. When it was realised that kiore were having a major effect on the environment and with advances in technology eradiation became possible.

While a controversial debate about poisoning occurred in the media. With checks and measures in place to reduce bird losses  a drop of an anticoagulant brodifacoum from a helicopter was carried out in 1993. Ninety percent of pukeko were killed after the poison drop and some ground feeding birds brown quail, blackbirds, sparrows and mynas were also decimated. Little spotted kiwi, North Island saddlebacks and North Island robin populations were not detrimentally affected.

The poison drop resulted in the eradication of kiore and as a result kakariki and brown quail enjoyed a population boom and kohekohe and native broom and other plants species flourished. The success of kiore eradication on Tiritiri Matangi has lead the eradication on larger islands Kapiti in 1996 and Little Barrier Island in 2004.

The success of Tiritiri Matangi is dependent on it remaining predator free and so continual vigilance and education are required ensuring people are rodent aware and pest monitoring or tracking is carried out over the island to detect the presence of unwanted predators.

References:
Anne Rimmer (2004) Tiritiri Matangi; Tandem Press, Auckland New Zealand
http://www.gbict.co.nz/Newsletters/Issue7/Island Rat Eradications

Argentine Ant

The vigilance of a DOC entomologist lead to the discovery of Argentine ants near the wharf in 2000. These ants arrived here from the wharf building material and the whole nest is moved, not one or two ants. They are one of the world’s most invasive species overtaking our native ants and so a 5 year eradication programme was set up.

They eat a wide variety of foods, have been reported to attack nesting birds and kill nestlings, and invade native ecosystems and displace native ant species. They produce multiple queens and can form huge super-colonies that extend for thousands of kilometres.

Luckily the ants were only discovered at two locations near the wharf and at Northwest Bay. The eradication involved hand laying bait at 2-3m intervals on a grid.  This involved the help of many volunteers and favourable weather. By 2004 only two nests remained and these were spot treated to ensure there total eradication. This is the first time a total eradication of ants has been achieved in such a large area of New Zealand.

Preserving Tiritiri Matangi’s biodiversity is an easy task to avoid another chance introduction like the Argentine ant, when all visitors take these simple precautions.

• clean footwear/packs and pockets to avoid introducing weed seed
• store items in pack or pest proof containers

check with Department of Conservation when transporting building supplies or bulk materials

References:
Anne Rimmer (2004) Tiritiri Matangi, Tandem Press, Auckland New Zealand
DOC Biosecurity Information - Argentine Ants
R. Griffiths, May 2005 Biosecurity: Protecting Tiri from Pest in Supporters of Tiritiri Matangi Dawn Chorus Bulletin 47