The warm climate, steep terrain, high rainfall, bioclimatic diversity and range of forest types in te Raukūmara makes it the perfect place for pest animals to flourish.

 

Since the mid-1800s, the following introduced species have been identified:
 

• red deer (Cervus elaphus scoticus)

• brushtail possum (Trichosurus vulpecula)

• feral goat (Capra hircus)

• feral pig (Sus scrofa)

• feral cattle (Bos taurus)

• rabbit (Oryctolagus cuniculus cuniculus)

• hare (Lepus europaeus)

• stoat (Mustela erminea)

• weasel (Mustela nivalis vulgaris)

• feral cat (Felis catus)

• ship rat (Rattus rattus)

• Norway rat (R. norvegicus)

• house mouse (Mus musculus) and more.

​

These introduced species have compromised the ecological function of the ngahere creating the following impacts:

​

• Reduced seed dispersal and plant pollination

• Reduction in species habitats

• Forest hydrology is changed, increasing runoff, reducing absorption and altering river flow rates.

• Soil health is reduced, with leaf fall, soil composition, invertebrate habitat, nutrient cycles and mineral fixing processes all impacted. 

​

Possums, rats and stoats

​

Possums, rats and stoats have created particularly bad impacts on te Raukūmara. They have caused immense damage to the forest canopy and understory, and pushed many taonga species to the point of extinction.

Possum trappers and monitoring data tell a story of moderate to extreme levels of possums at 90 percent of the sites under observation in te Raukūmara. Some sites record extremely high levels of possums that are among the highest ever recorded in New Zealand national data.

 

While there has been some commercial possum control operations on peripheral parts of te Raukūmara, the steep terrain, difficulty of access and isolation means possums in the interior have been left almost completely unimpeded by trapping or other conservation control measures.

 

Recent observations at mid to high altitude levels show the staggering impact of possums on taonga trees such as Hall’s tōtara (podocarpus laetus), with up to 90 percent of this species being reported as severely damaged or dead.

​

While trapping can be effective in more accessible areas, landscape-scale aerial 1080 operations are the only way to control possums, rats and mustelid populations in the most remote, isolated and steep interior terrain of te Raukūmara.

​