Mokoia Island

Forest and Bird, Issue 314, 1 November 2004, Page 18

Mokoia Island

JASON ELSWORTH

visits a wildlife refuge

in Lake Rotorua where cultural and conservation values are preserved.

best impression of a log, and carefully watching not one but four saddlebacks, foraging contentedly right in front of me. I’m not in some remote offshore reserve, but instead in inland Bay of Plenty. Mokoia is a 135-hectare predator-free reserve in the middle of Lake Rotorua and is home to the largest mainland population of saddlebacks in the country. It is a place where native flora and fauna can flourish sitting quietly in the bush, doing my too. Mokoia was formed when magma that was slowly cooling below the surface of the collapsed volcano that formed Lake Rotorua erupted again. This dramatic beginning was the start of a long and fascinating history for the island, only a few kilometres from the centre of Rotorua city. With its fertile soil and strong defensive position, Mokoia has always been a prized location. As a result it has been the subject of many bloody — and, more recently, legal — disputes. Mokoia’s bloodiest hour came during the musket wars, when in 1823, Ngapuhi, led by Hongi Hika, came down from the north. Hapu around Lake Rotorua sought safety on Mokoia, but Ngapuhi had carried their own canoes inland with them and, as they had many more muskets than the tribes on the

island, a slaughter ensued. Hundreds of men, women and children were killed. In stark contrast, however, Mokoia Island is also the setting for one of the most romantic of Maori tales — the story of Tutanekai and Hinemoa. The story is a classic tale of forbidden love, which sees Hinemoa swimming to Mokoia, across the lake, to be with her love Tutanekai. In the twentieth century the battle for Mokoia became a legal one, starting in 1916 with a Maori Land Court hearing. Various hapu submitted 29 claims and after 11 long months the successful hapu were Ngati Whakaue, Ngati Uenukukopako, Ngati Rangiwewehi and Ngati Rangiteaorere. Today Mokoia is a private wildlife refuge, managed by a board of trustees made up of representatives from each hapu. The Jonz Corporation has a long-term licence from the trust board, and is responsible for the island’s day-to-day management and for all visitor activities. John Marsh, the managing director of Jonz Corporation, is a descendant of Hinemoa and Tutanekai and has an inspiring vision for the island and how it can change people. Along with the Mokoia Island Trust Board, Jonz Corporation intends to ‘develop the island for iwi cultural and native flora and fauna conservation.’ The journey toward Mokoia becoming a place for conservation has been long and eventful. Broadleaf podocarp forest would once have covered Mokoia, but the island

was also perfect for cultivation — kumara being the main crop. Turning Mokoia into a garden, however, required extensive clearing, burning and terracing, destroying much of the original forest. The modification of Mokoia’s habitat continued when the first Europeans arrived in the early 1800s, bringing with them non-native flora as well as rats, mice, cows, sheep and goats. The first attempts to restore Mokoia to a pre-European habitat were made in the 1960s, when thousands of small trees and ferns were planted. Unfortunately rats destroyed most of them. No other restoration attempts were made until 198990, when Paul Jansen of the Department of Conservation, coordinated the eradication of rats, goats and sheep. Next, helicopter drops of brodifacoum in 1996 and 2001 eradicated mice. Rats have occasionally reappeared on Mokoia since the eradication so an extensive network of bait stations and tracking tunnels now covers the island. Eradicating rats, sheep, mice and goats gave the bush the chance it needed to grow and the forest on Mokoia has recovered well. ‘The forest is in very good condition, says Keith Owen of DoC Bay of Plenty. ‘It has really regenerated substantially from where it was and the bulk of the centre of the island is weed free. The main plant species now present on Mokoia are five-finger, mahoe, kawakawa, kohuhu, tree ferns (especially on the southern half of the island), whau, cabbage trees, kohekohe, and karaka. In 1999, two species of mistletoe (Ileostylus micranthus and Tupeia antarctica) were translocated to Mokoia. Some invasive European plants remain, but a huge growth of blackberry

which once covered much of the island's flat areas has now been cleared. The final part of the island’s ecosystem is Lake Rotorua itself. Unfortunately, waste from pastoral farming around the lake causes high levels of nitrogen to leach into the water. This leaching, combined with the high levels of phosphorous found in the lake, has introduced an artificially high level of nutrients. These nutrients promote algal growth, which significantly degrades the lake’s water quality. To counter this,

Environment Bay of Plenty has developed an action plan, which aims to coordinate the efforts of local stakeholders and reduce the level of nutrients in the lake. Since the rat eradication, four bird species have been brought back to Mokoia: New Zealand robin (toutouwai), stitchbird (hihi), saddleback (tieke) and North Island brown kiwi. Weka were transferred from the Gisborne area in the 1950s and, according to Keith Owen, there are ‘probably between 80100 weka on the island. The first of the reintroductions was seven male and 10 female New Zealand robins in June 1991. The robins have thrived on Mokoia and, in 2003, robins were taken from Mokoia and released on Mayor Island/ Tuhua in the Bay of Plenty. The next species to come home to Mokoia was the saddleback in 1992. After the reintroduction a team of researchers from Massey University carefully studied the saddlebacks. Research found that the population grew well, from the original 36 released in 1992, to 200 in 1997. The saddleback reintroduction has been a total success, according to Dr Isabel Castro of Massey University. Not so the stitchbird. Following the saddleback reintroduction, 40 stitchbird or hihi were released onto Mokoia in 1994. Reintroducing hihi, however, proved to be much more difficult than saddlebacks. ‘It was one of the most challenging reintroductions [in New Zealand] so far, according to Dr Castro. Mokoia, with its modified and regenerating habitat, was unlikely to have enough fruiting and flowering flora to provide sufficient food, and the island lacked the type of large trees hihi prefer for their nests. So to help the hihi get established, they were provided with food, via supplementary feeding of sugar water, and accommodation, via nest boxes. Following the release, extra food was provided every year (except 1998-99) until August 2002, when the birds had to be removed from the island. Initial research, again by the Massey University Ecology Group, unexpectedly found that providing food had no affect on the survival rate of adult hihi. Even with supplementary feeding only four out of every 10 hihi would survive from one year to the next. ‘Predictive modelling’ showed that the future survival of hihi on Mokoia was far from certain. The researchers concluded that something other than lack of food must have been affecting the hihi population’s chance of survival. But what was it? A clue to exactly what was killing off the Mokoia Island stitchbirds could be heard in the songs of some of them. Their normally

crisp, high-pitched call was developing a slight rasp, one of the initial symptoms of a lung infection known as Aspergillosis. Autopsies of hihi lost on Mokoia between 1995 and 1997 confirmed that in many cases (19 percent) the culprit was indeed Aspergillosis, caused by Aspergillus fumigatus fungal spores. A further 44 percent of the birds lost, displayed symptoms of Aspergillosis, but their carcasses could not be found. The fungal spores that cause Aspergillosis are found in the soil and easily inhaled by the birds. Unfortunately, the infection is not treatable in the wild. Further research, by John Perrott and Doug Armstrong from Massey University, indicates that habitat disturbance and modification (highly prevalent on Mokoia) appears to promote A. fumigatus. Mokoia has much higher levels of the fungus than on Tiritiri Matangi Island, where, in 1995, hihi were successfully reintroduced. It now looks likely that Aspergillosis is the reason why, despite intensive management, the introduction of hihi to Mokoia proved so difficult. In 2002 the Department of Conservation decided to remove hihi from Mokoia and transfer them to Kapiti Island. Despite the

failure, a vital lesson was learnt — in some cases the tiny and easily ignored A. fumigatus fungus may be just as dangerous an enemy as any predator. Today, a predator-free Mokoia Island is alive with birds. Tui dogfight above your head, fantails dance along with your every step, silvereyes and grey warblers flit from tree to tree and, if you pause to stop anywhere in the bush, it won't be long until you have a North Island robin or a saddleback for company. The latest introduction of four North Island brown kiwi in 2003 has also brought our national icon back to the island. Mokoia Island’s journey back to being a place where native flora and fauna can flourish has been long and eventful but, as you sit listening to the chattering of a foraging saddleback, the future for Mokoia certainly looks bright. — JASON ELSWORTH is a freelance writer and photographer of nature.

To visit Mokoia Island contact the Jonz Corporation — 0800 665 642 or mokoia.island@xtra.co.nz