Threats to the Island

Little Barrier's unique ecosystem is under constant threat from plant and animal pests.

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Weeds/Exotic plant pests


Introduced exotic plants threaten to destabilize the delicate balance of flora and fauna on the island. Most of these noxious plants start their journey to Little Barrier (Te Hauturu-o-Toi) from people's gardens on the coastal mainland. Their seeds are carried across the Hauraki Gulf by birds, by the wind, or even by sea. They can also be transferred unwittingly by people, on their clothes or equipment, so constant care is necessary.

The Department of Conservation (DOC) is working to bring weed problems under control through an annual eradication programme. Specific weeds being targeted are climbing asparagus and pampas grass. All are particularly invasive and, if left, would destroy or permanently modify the ecology of the island, thus threatening the birds and other species that depend on the native forest plants for food and shelter.

The Trust has contributed annually to this war on weeds. For example, it funded several steps in the attack on climbing asparagus, when it was the most immediate threat to the island's ecosystem; and it has taken responsibility for eliminating prickly hakea from a section of the island where it had become firmly established. Funds have also been provided for several years to assist with the control of pampas.


Animal pests


Hauturu has suffered less from introduced animal pests than most New Zealand habitats. From the very long list of mammalian predators brought here by human hand, only two reached Hauturu: Pacific rats (kiore) and cats, which rapidly became feral. In a groundbreaking and sustained operation, wildlife officers achieved the seemingly impossible: eradication. By 1981, they were able to declare Hauturu cat free. Birdlife benefited dramatically. Attention then focused on the increasing numbers of kiore (rats). Their adverse impact on every level of the ecosystem has now been well documented. In 2003, DOC initiated a programme to eradicate kiore, the Pacific rat, from the island. The Trust acted in support of this programme. The eradication programme was carried out in 2004. The subsequent two-year monitoring period and final island-wide survey confirmed its success. With both rats and cats eliminated, Hauturu tuatara could be set free.


Protection


Despite these plant and animal pests, Hauturu has maintained an exceptional degree of biodiversity. Freed of them, the island can forge ahead to achieve its full potential as a wildlife sanctuary, a rich treasure-house of New Zealand species. Hence the importance of DOC's 'No Landing' policy. In order to prevent any new pests gaining a foothold and wreaking havoc on the island constant vigilance is required. Once ashore, dogs, cats, and ferrets could quickly become pests. And the unseen passenger on many vessels, the rat (especially a pregnant one) is potentially even more dangerous.Consequently, visits to Hauturu are controlled and a permit is required for people wanting to visit the island. Permits are issued by DOC and reasons for visiting are usually for scientific or conservation purposes.

Did you know?
Hauturu is the site of the largest natural populations in the conservancy of shore spurge (Euphorbia glauca). The only other site is Motukorea/Brown's Island, where restoration is underway from the one plant that remained.