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New Zealand is the only major country in the world with no native land mammals, apart from a few species of small, ground feeding bat. This has permitted the development of a large number of unique birds, reptiles, frogs, arthropods and molluscs. Our plant life, in contrast, shows many similarities to other species in SE Asia, Australia & Oceania. With no mammals, the whole animal predator/prey/food relationship in New Zealand is different from the rest of the world and our native trees and other plants have evolved with little resistance to the effects of mammalian browsing & grazing. In the absence of mice or mammalian predators our giant wingless crickets, known as weta and weighing in at up to 50 gm, fill the ecological niche occupied by European field mice. These are amongst the largest insects in the world. In the absence of grazing & browsing mammals, the flightless moa, as large as an ostrich or rhea, became widespread with forest species and lowland species; again, filling an ecological niche. With the first Maori settlers some 1000 years ago, land clearances and hunting started to take a toll of the indigenous animal populations. The influx of European settlers 200 years ago introduced a number of serious mammalian predators and pests and vastly increased the rate of habitat loss. In less than 1000 years, we have lost 43% of the frog fauna and over 40% of the bird fauna; the giant gecko has gone along with the flightless wrens, giant eagle and moa. Most lowland forest has given way to agriculture and plantation forestry, and most wetlands have been drained. Remaining ecosystems have been invaded by alien plants, are browsed by alien herbivores and are preyed on by alien mammals. New Zealand now has as many threatened species as the whole USA (over 600). Over the last 35 years, New Zealand has had a great deal of success in creating many off-shore island reserves, where endangered species, particularly ground nesting birds, have been shown to thrive in the absence of mammalian predators. Places like Tiritiri Matangi, Little Barrier & Cuvier Island, all in the Hauraki Gulf; Maud and Stevens Islands in the Marlborough Sounds, and many other islands. The basic principal for these off-shore islands has been the vigorous and intensive removal of predators (cats, rats, possums, ferrets, stoats, weasels), competing mammals (mice & hedgehogs) and habitat destroyers (feral goats, pigs & deer), followed by creating mechanisms to ensure that they do not return, principally by controlling boat landings. Revegetation projects follow, but are often supplementary to natural, spontaneous forest & bush regrowth. By 1989 it was felt that NZ now had a sufficient level of expertise to create protected ‘islands’ on the mainland of New Zealand, protected either by a zone of intensive pest control, or by the erection of pest proof fences. Mapara in central North Island was the first of those and a number of others have since been created. Karori in suburban Wellington, Mangataupiri Mountain in southern Waikato and Cape Brett at the top of North Island are other examples. One of the aims of the Moehau Environment Group is to help stimulate community & iwi involvement to create a similar Mainland Island in Cape Colville. A pest control fence some 8 km long would span the Coromandel Peninsula from coast to coast (5km as the crow flies) just north of Colville township and provide protection to over 17,500 hectares of some of the finest dense forest montagne environments in North Island. MEG is actively involved in coordinating this discussion and creating a steering committee to realise this vision. DoC and Environment Waikato are putting a very serious effort into pest control in our area because, basically, Cape Colville is one of the few pristine areas in the Waikato region and it has the highest kiwi population. There is a major DoC monitoring kiwi monitoring programme in place. There are probably some 500 kiwi living in the Moehau Ranges. Some 40 of them are radio tagged and named individually. The Australian Brush-tail Possum first arrived in Cape Colville only 22 years ago. Imported from Australia into NZ by entrepreneurial fur farmers in the early 1900’s and released or escaped into the wild after their business failed. They have taken a long time to reach the Cape Colville but have created a lot of damage in a short time. As well as destroying residents’ fruit crops, possums have had a devastating effect on Rata. Driving down the hill to Port Charles, look over to your left on the far side of the valley; there are several skeletal trees that are possum destroyed rata. Sailing around the coast from Port Charles to Waikawau, particularly around Three Stone Bay, one sees the same skeletal trees. Possums are commonly regarded as vegetarians, nibbling on growing plant tips and taking bites out of under-ripe fruit. But they have also been filmed eating eggs and nestling birds. This link provides more background information to the NZ government position on the concept of Mainland Islands.
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