Predators are those species which kill other animals for food. This is a natural part of the life/food cycle and prey species evolve (change over time) or die. Because of the fast introduction of mammalian predators to New Zealand, our native species have not adapted to evade predators and have been overwhelmed with their sheer numbers.

The introduction of these mammalian predators have decimated our native species, some to the point of extinction. The aim of Predator Free Hamilton is target the main offenders (those species that do the most damage), which are Rats, Possums and Stoats. Other introduced predators include Ferrets, Weasels, Hedgehogs and Cats.

Introduced animal pests by Te Ara (Encyclopedia of New Zealand)


Rats are self-introduced to New Zealand arriving as stowaways on ships. They are prolific breeders and have readily adapted to a diverse range of habitats throughout New Zealand. There are three species of rats found in New Zealand and all have had a devastating impact on our native fauna.

Rat species found in New Zealand by Maanaki Whenua Landcare Research

Rat Facts by Predator Free New Zealand Trust

Rats: NZ pests by Department of Conservation


Possums were introduced to New Zealand to establish a fur trade in the mid 1800s. They are nocturnal and omnivorous. They consume vast quantities of vegetation including leaves, flowers, buds, nectar, fruit & berries plus native insects, eggs and chicks. Not only are they predators of our native species, they are also competitors for food and nesting sites. They carry diseases such as Tuberculosis which are a problem for farmers in New Zealand. Other than feral cats, they have no predators in New Zealand. Compared to their home country of Australia, the abundance of food, mild climate and few predators, their numbers are very high and they are significant problem in New Zealand.

Possums by Department of Conservation

Possum facts by Predator Free New Zealand


The Mustelid family includes Weasels, Stoats and Ferrets. They were originally introduced to New Zealand to control rabbits but found our native birds much easier prey.

Mustelids by Christchurch City Library


Stoats are formidable hunters taking on much larger prey than themselves. They have good eye sight, good hearing and a keen sense of smell, all ideal for hunting. They are agile climbers and good swimmers and have been described as the ‘ultimate killing machine’.

Stoats by Department of Conservation

Stoat facts by Predator Free New Zealand Trust


Hedgehogs were introduced to New Zealand by European settlers to remind them of home and to control garden pests such as snails and slugs.

Hedgehogs are not considered predators by many people however, they have a huge impact on native insects. They are mostly insectivores and eat native weta, snails and other insects but they also eat skinks, frogs, eggs and chicks of ground-nesting birds.

Numbers of hedgehogs are thought to be much greater than people realise. New Zealand lacks many predators of hedgehogs and with such a mild climate, hedgehogs have flourished.

Hedgehogs by Department of Conservation

Hedgehog pests by Pest Detective

Hedgehogs: recent evidence of their effects on native fauna by Manaaki Whenua Landcare Research. Look in Issue 31.