Discovery

Bright Future for Mokoia Island

Mokoia Island, long sacred to the local Maori people, has long been one of the most beautiful but perhaps least appreciated natural features of the Rotorua region.

The lack of appreciation is about to change, thanks to Department of Conservation staff in Rotorua, who have long held the idea that Mokoia could become a predator and pest-free haven for a vast array of New Zealand's native species. This dream is now coming true thanks to assistance from Rotorua Lakes High School biology students and encouragement from the Mokoia Island Maori Trust Board.

In August 1994, DoC took a team of Rotorua Lakes students to Little Barrier Island in Auckland's Hauraki Gulf for a capture and release operation that would see some 40 stitchbirds caught and transferred for release onto Mokoia Island. The team, led by Paul Jansen, Senior Conservation Officer for the Rotorua/Bay of Plenty conservancy, used mist nets to capture the birds, which were then transferred to aviaries on the island before transfer and release on Mokoia Island.

In 1992, some 36 saddlebacks were transferred to Mokoia in much the same way.

Despite these achievements with birds, there was still one stumbling block preventing DoC from introducing other endangered species of lizards, invertebrates and snails to the island -- the presence of very destructive mice.

Rats had previously been eradicated from the island by 1989, but mice remained, flourishing in the absence of competition from the larger rats by eating plant seeds vital to saddlebacks, stitchbirds and other species and attacking eggs, lizards and invertebrates. The mice would pose a threat to any newly introduced species, who would run the risk of being eaten themselves, having their food supplies depleted or having their eggs destroyed. The mice had to go.

The biggest problem facing DoC was that they knew very little about just when mouse populations were at their greatest on the island and when they dropped away in the yearly bust at the onset of winter. These times had to be accurately ascertained before eradication by poisoning could take place. It was here that Lakes High came into the picture again.

Sixth form biology students were called upon to lay four lines of plastic runs covering the island. Each run had a peanut butter bait, an ink pad and a small strip of paper. The idea was that the mice would go through the run to get at the peanut butter and would thus leave behind their tell-tale footprints.

The scheme has so far worked well and DoC is fast learning the activities of these covert critters.

What of the future? DoC has yet to decide with local Maori upon an exact plan for the island.

To help decide upon the best course of action for Mokoia Island, DoC took a group of Lakes High students to Mana Island near Wellington to compare the eradication and preservation policies and ideas applied there to Mokoia and any future preservation policies for the island. The trip gave them an opportunity to see some of the rarest species in New Zealand, including the takahe, little spotted kiwi and McGregor's skink. Mice were eradicated from Mana Island in 1989 by the setting of some 5000 bait traps across the island at 25-metre intervals. This method is one possibility for Mokoia, but aerial poison drops are also being considered.

As well as looking at mouse eradication techniques, the students "brain-stormed" a variety of possible management plans for Mokoia, including the concept of bringing the island's habitat back to the state it would have been before humans came to the Rotorua region. Mokoia would become an eco-reserve where one could see a vast array of New Zealand's native species in their natural habitat and get an impression of what New Zealand would have been like if humans had not been around. This idea could incorporate tours of the island which could, if controlled properly with checks for predators and pests on boats, earn Rotorua extra tourist revenue.

"Whatever the decision is on the future of Mokoia Island, it is bound to be a good one, as Mokoia Island has always been and always will be a place of pride, history and natural beauty for the people of Rotorua. Mokoia Island stands in all its beauty as a statement to humankind of what can be achieved if the hearts of the people are really devoted to the natural beauty of their home, and a challenge to others to preserve the environment of their region," says Morley West, biology teacher at Rotorua Lakes.

The above is the winning entry in the Discovery Science Journalism Competition. Excerpts from some Highly Commended entries follow:

John Mitchell is a sixth form student at Rotorua Lakes High School. He won $150, a Telecom Collector's Cardphone Pack, a copy of Magic Eye III from Penguin Books and a year's subscription to the NZSM. Well done!