The brush tailed possum is the most common possum in New Zealand and just about the only species of possum in New Zealand. The brush tailed possum was introduced into New Zealand in 1850s by the Australians for a fur industry. It is now a great threat to New Zealand's native birds and plants. The brush tail possum is nocturnal like most possums and they feed on small mammals and birds like rats, mice, bird eggs and birds. But they mainly eat leaves, fruit and insects. The tail is thick and hairy on the top but is naked on the underside. The naked part of the tail is used for clinging onto branches and climbing. The are four colour variations brush tail possums come in; black, grey, brown and gold.