Possums were introduced to New Zealand in the 1800s, and since then, have caused considerable destruction to New Zealand's environment.
In New Zealand, possums are taking over native bushland, pushing out native species of birds, for which New Zealand is unique. Possums eat the birds' foods, nest in their trees, and are one of the greatest threats to native bird species. They have been recorded eating eggs and chicks from birds' nests.
Their feeding habits also disrupt the food supplies for native bats, lizards and even insects. They feed on the vegetation, reducing its availability for native species, and nest in the trees, forcing smaller species out. There are no natural predators of the possum in New Zealand, so their population has increased dramatically.
Possums strip the native plants of leaves, buds, flowers, fruits and seeds, meaning less chances of propagation. New Zealand trees do not have defensive chemicals of some Australian native trees, meaning the possums can continue to eat from one tree until the tree has been severely affected. Many of these plant species are disappearing from the New Zealand forests, and allowing invasive non-native species to take hold of the forests.