Case studies

Kapiti Island

In 1983 Kapiti Island was made possum-free. This program involved two thirds ground control covering the accessible areas and aerial application on inaccessible areas (around 17% of the island).  Native vegetation kohekohe, rata, and fuchsia rapidly recovered. By 1988 monitored native bird densities had doubled.31

Rangitoto Island

Prior to a 1990 possum eradication programme using 1080, Rangitoto Island's pohutukawa forest was dead and dying.  Rangitoto is now a blaze of healthy pohutukawa, flowering throughout the summer.  Monitored bird life records show that since possums were eradicated there are 10 times more tui and silvereye living on the island.32 Honey production on the island pre-1080 possum control was 7kg per hive. One year later it rose to 25kg per hive, and two years later it was 50kg per hive.33

Kahurangi National Park

Kahurangi National Park was suffering declining populations of native snails.  In 1997 a major aerial 1080 targeting was undertaken. Pre-1080, there were 54 snails found on a 500sq m grid. One year after 1080 was applied, 147 snails were found on the same plot.34

Tongariro Forest

Nationwide studies show that on average only 5% of kiwi chicks survive to adulthood.  Prior to an aerial 1080 application in Tongariro Forest in 2001, 32 kiwi chicks were radio-tagged. After the 1080 programme, 40% of the radio-tagged chicks survived to adulthood.35

Hurunui, Hawdon and Eglinton valleys

The South Branch of Hurunui, Hawdon and Eglinton valleys all had substantial populations of mohua.  All three populations declined during the 1990s and all collapsed to very low levels during a rat and stoat plague over the 1999-2000 season.  After a comprehensive pest control programme, including aerial 1080 application in 2006 mohua are now abundant in areas that received treatment but have declined elsewhere.36


Pureora Forest Park

In Pureora Forest Park 20 kaka were radio-tracked in an area to be treated with aerial 1080 in 2001.  In nearby Waimanoa Forest, which was not to be treated with 1080, nine kaka were radio-tracked. In the area where 1080 was used, all 20 birds survived that season. Of the nine birds tagged in the untreated area, five were killed by predators that same season.37

Whirinaki Forest

During a 1998 to 2002 study in Whirinaki Forest 17 kaka and 15 kereru were radio tagged and monitored throughout an aerial 1080 operation, and for two weeks afterwards. All of the 17 kaka and 15 kereru survived in the area treated with 1080.38


In total, 73 kaka have been radio-tagged and monitored through four 1080 drops.  In two studies they were monitored for a year afterwards.  Every single bird lived.39

New Zealand Falcons

In a study on the breeding success of New Zealand falcons in a pine plantation over three breeding seasons, it was found that New Zealand falcon numbers in the Kaiangaroa Forest increased from 20 to 36 pairs following aerial and ground 1080 control.40
  Kaka pair (Source: Forest and Bird, Photo by Jordan Kappely)