Possums have become a widespread pest in Auckland, severely damaging what is left of the native forests. Possums favourite foods include the foliage of pohutukawa, rata, totara, and kowhai, as well as flowers of native trees (which means they are eating the food source of our nectar-feeding native birds), eggs and chicks of native birds, native invertebrates, pasture plants, crops and shelter belts. In an urban environment, possums can also become a nuisance to residents, as well as pets.

Te Ngahere provides a comprehensive trapping service for possums using Timms traps. Timms traps are a tough, lightweight plastic box that humanely kills a possum upon capture. The possum pokes its head through a hole to take the bait and triggers a powerful spring, which clamps a metal bar across the throat, cutting blood supply to the brain.

Another method used by Te Ngahere to control possum numbers is the use of bait stations. Bait stations offer advantages over traditional trapping and shooting, where the aim is to bring possums down to very low levels and then undertake ongoing maintenance. The use of bait stations reduces the risk of non-target species (birds and dogs especially) eating the bait.

A Pestoff, highly palatable, anti-coagulant pellet bait is currently used, the active ingredient being Brodificoum. A lethal dose is approximately 100 grams of bait. The advantages of using Pestoff include:

• the long delay between consumption of the bait and the possum feeling sick means that it is ideal for killing possums

• the long delay between consumption of the bait and the possum feeling sick also means that a "social attraction effect" occurs, the actions of the possum (who first discovers the bait station) returning nightly to the station attract other possums

• reduces the rat and stoat population dramatically, as well as possums Pestoff provides an additional bonus, by controlling rats and to some extent stoats and ferrets (through secondary poisoning)

There is evidence that the use of toxins to control possums and rats can benefit individual forest species as well as forest systems in general. Preferred possum food species, such as northern rata, fuchsia, kohekohe and totara have shown significant recovery after heavy reductions in possum numbers. For example, a 30-year possum control programme using 1080 in the Otira Gorge of Westland has shown positive results where giant southern rata now flower regularly and possum-vulnerable fuchsia trees, along with other native plants, are thriving (Doc website, 2005).

Closer to home, the efforts of the Auckland Regional Council, Department of Conservation, and numerous volunteers in the Hunua Ranges Regional Park have reduced possum and rat numbers to very low levels. As a result, approximately 30 kokako fledged, and there are now 9 kokako pairs within the management area in comparison to one pair in 1994 (Auckland Regional Council website, 2005).