Pests Cause and Effect

Continuing our inquiry into the native bush we collaborated on a cause and effect of introduced species to New Zealand.

Possums, rats and stoats have had a huge impact on our environment since their introduction to Aotearoa. To combat these pests New Zealand has an ambitious aim to be rid of them all by 2050.

Possums

Possums were introduced to New Zealand from Australia in 1837 to establish a fur trade. However there numbers soon grew to such an extent that there is now approximately 30 million possums in New Zealand. The effect of this invasion is the serious damage of native trees. Possums eat a huge number of leaves. This can stress a tree so much it will eventually die. Some forests have lost all of their rata and kamahi, two of the possum’s favourite species. Possums have no natural predators in New Zealand therefore numbers must be controlled with traps, poison and by being hunted.

Stoats -

Stoats are public enemy number one and were introduced to New Zealand by European settlers in 1879 to control the number of rabbits and hares.  An unexpected effect of their introduction though was to cause the extinction of many native birds. Stoats attack birds that nest in trees such as the mohua and kaka. Stoats can take out eggs, chicks and incubating adults in one go. The stoat has also caused many subspecies to become extinct such as the bush wren, laughing owl and the New Zealand thrush.

Rats -

Norway (brown or water) rats were introduced to New Zealand unintentionally by being stowaways on the boats and ships that arrived in the late 1700’s. The introduction of rats contributed to the extinction of some native bird species. Rats are especially dangerous because they are able to climb the trees and enter the nests of native birds.

Possums, rats and stoats are New Zealand’s most wanted pests having caused the destruction of the native bush and the extinction of native birds and animals. To protect our native forests, animals and plants we must rid these species from our shores for good.