Like other introduced animals, possums pose a significant threat to New Zealand’s indigenous biodiversity.

In Australia, forests evolved defences against browsing by possums. But in New Zealand, where some plants don’t have the same defences, possums have had a devastating effect. After two years of heavy possum browsing a tree will often die. In some areas they have eaten whole canopies of rata, kamahi totara, titoki, and kohekohe.

More recently it has been found that the supposedly vegetarian possum also eats bird eggs and chicks, including those of endangered species such as the kiwi and kokako. Large native land snails are also threatened with extinction caused by possums and other predators.

Possums can also carry and spread bovine tuberculosis among cattle, posing a major threat to New Zealand’s export meat industry. Possum control on conservation land therefore brings important benefits for the economy as well as to native plants and animals.

The Department of Conservation has an extensive possum control programme covering over 800,000 hectares of land in its care. Funding from the New Zealand Biodiversity Strategy allowed a further 46,000 hectares of high value conservation sites to benefit from possum control during 2001/02, and 11,600 hectares in 2000/01.

Biodiversity strategy funding for possum control operations from Northland to the deep south has brought benefits to threatened bird species, giant land snails and threatened plants.

Possum control is carried out with aerially applied 1080 (ten-eighty) poison. 1080 is an essential tool for maintaining New Zealand’s biodiversity that has brought proven benefits for forest health

More information about possums is available on the Department of Conservation’s website.