KOKAKO RECOVERY

Forest and Bird, Volume 23, Issue 2, 1 May 1992, Page 28

KOKAKO RECOVERY

Dr

GRETCHEN RASCH

JOHN CRAIG

_ HE PLIGHT of the North \ Island kokako (Callaeas cinerea wilsoni) first received wide-spread attention in the late seventies when Rod Hay began his pioneering «¢ %= research sponsored by Forest and The results showed clearly that the main reasons for kokako decline (and the decline of other specialised endemic species) were loss of forest habitat through logging, and competition and predation from introduced mammals. In the late 1970s and early 1980s the protection of New Zealand’s native forests was the main focus of conservation activity. As a bird dependent on the integrity of the forests the kokako became a symbol of this movement. The swing of public sentiment against logging, powerfully demonstrated by letter-writing campaigns and tree-top protests in the important kokako forest of Pureora, finally saw a reduction in the destruction of indigenous forests. When Crownowned forests were transferred to the Department of Conservation in 1987, logging stopped on these lands. On private land a breakthrough was achieved in the Tasman Accord, in which Tasman ae se ae ee

Forestry agreed to protect its native forests. This example from the largest forestry company paved the way for the New Zealand Forest Accord in 1991 negotiated between Forest and Bird and the forestry industry, so ending the era of wholesale native forest destruction for pine plantations. But though the kokako’s forests were largely saved, the birds continued to decline. The knotty problem remained of introduced mammals — the predatory rats, stoats and wild cats, and the possums, goats and deer which compete with the kokako for food and degrade its forest home. In 1985 help came from an unexpected quarter to the kokako forests of the King Country. Bovine tuberculosis had been spreading through the possum population in the western Taupo area towards the Waikato dairy herds, so the Ministry of Agriculture initiated a poisoning campaign to reduce possum numbers. Concerns about the possible effect of the 1080 poison on kokako resulted in a four-year programme which monitored kokako in Pureora forest during poison drops. During six poison operations only one of 83 kokako was reported missing, presumed poisoned. This small loss was

offset by the huge benefit to the kokako as their forest and food source recovered from the effects of possum browsing. By the end of the 1980s it was evident that new advances in kokako management were needed, because on-going work was beginning to raise some crucial questions. Are kokako continuing to decline in the large forest tracts such as Puketi, Pureora, Mamaku Plateau and Te Urewera National Park? What are the exact effects of predators and browsers on kokako? Is management really helping kokako at all? In June 1988 fifty people attended the Kokako Research and Management Workshop in Rotorua. The enthusiastic team of biologists, managers and conservationists discussed the most critical work needed to save kokako. A group of specialists was chosen to develop a recovery plan. Both the group and the plan evolved over the next few years, and the recovery plan was finally approved by the New Zealand Conservation Authority

and the Department of Conservation late last year. The committee overseeing the administration of the plan includes representatives from Forest and Bird and the Forest Research Institute. The aim of the recovery plan is: * to protect key populations of kokako. These are populations which will contribute most significantly to the species’ survival * to carry out research that will help to understand the bird’s complex ecology and habitat * to evaluate current management techniques for kokako * to use techniques such as island transfers and captive breeding to conserve remnant populations.

HILE IT MIGHT seem obvious that predators and browsers are causing kokako to decline, the evidence is largely circumstantial. Kokako nests are notoriously hard to find. No one can say with certainty that kokako are declining because they aren’t trying to nest (which would suggest that browsers are limiting food so therefore the birds can’t get enough nourishment for reproduction), or that kokako are breeding but eggs, chicks, or adult birds are being killed by stoats, rats or other predators. Is one more important than the other? Work at Rotoehu forest by John Innes (Forest Research Institute Rotorua), Paul Jansen (DoC Rotorua) and others will help answer these questions. Radio transmitters are being attached to adult birds, allowing workers to spy on the birds’ nesting attempts (see Forest & Bird May 1990). In the first year, only one of five pairs attempted to breed — and the eggs in that nest were destroyed by an unknown predator. In the summer of 1990-91

twelve pairs did their best and made 16 attempts at producing clutches. Young kokako survived from just two nests and rats were usually responsible for the loss of the others. This summer only one nest was successful despite eight nest attempts. Another objective is to develop the management methods which will allow kokako to keep on producing enough offspring to maintain populations. The task is very complex. Browsers and predators can switch roles, and management techniques can have unexpected effects. Browsing animals like possums may dip into a kokako nest for a quick feed. Poisons such as 1080, which target possums, are very effective against predatory rats. When rat is taken off the menu, a hungry stoat may increase the number of birds in its diet. Kokako do not cooperate either, and many frustrating hours can be spent tracking elusive parents and their offspring. It takes highly motivated people to carry out the job of controlling goats, possums, mustelids and rodents in the

The decline of the North Island kokako encapsulates the problems of wildlife conservation in New Zealand. This bird, of ancient lineage and haunting tone, is the only species of the endemic wattle bird family still living

on the mainland,

looks at the recovery prooramme for the kokako’s dwindline mainland

populations.

KOKAKO

research-by-management areas. The "gamekeeper" approach suggested ten years ago by Rod Hay is being used at Mapara, where Philip Bradfield looks after the 1,300-ha reserve. He is assisted by Te Kuiti and Hamilton DoC staff, and this summer they recorded three successful nestings. Sponsorship from Tasman Forestry through the Threatened Species Trust, administered by Forest and Bird, supports a similar project at Kaharoa, where Hazel Speed is reporting promising results. Last summer she found six pairs of kokako and two nests successfully reared chicks. This summer there were ten pairs of kokako,

and young fledged from three nests. While the increase in successful nesting is encouraging, the increase in kokako pairs may be even more significant. It suggests that forest territories which previously only supported a single kokako may now provide food for a pair, because the forest is rejuvenating after the removal of goats and possums. ARD DECISIONS must be made today when conservation resources are limited. There are 29 discrete populations of kokako, and not every population can be

intensively managed. Choices must be made as to which populations are more important, and the chosen populations where management may be most effective are Pureora, Mamaku (including Kaharoa), Urewera, Rotoehu, Mapara, Puketi, Little Barrier, Great Barrier and the Hunuas. Kokako surveys and research have concentrated on the central North Island forests and, only last summer, new surveys found an unexpectedly large number of kokako in the Ureweras. Nearly 300 were recorded in the Waimana valley area, suggesting a major population exists in this remote, rugged wilderness.

Kokako recovery: for whom and at what cost?

a zoologist from Auckland University, has questioned the effectiveness of a mainland kokako recovery

programme. He argues that the money could be better spent on offshore island programmes. Although Forest and Bird supports the mainland programme we believe it is important to canvass other views on this issue.

UCH RARE species work is based on a belief that organisms have measurable habitat requirements. Researchers document the ways animals and plants currently use their environment and use this as a guide to the habitat needs of that organism. However, this approach has a number of important problems. Firstly there is an assumption that animals and plants are optimally adapted to the environment we find them in and that they will not do as well or better anywhere else. It also assumes that present day habitat is the same as past habitat. Another problem is in the assumption that what organisms do is determined by genetics; that behaviour is fixed and hence they cannot learn to do other things. How likely are these aspects true for kokako? Kokako are described in the recovery plan as birds that inhabit forests, especially tall forests, that maintain large territories and have a low breeding rate. Hence to manage kokako one needs a large area and tall forests. But the historic distribution of kokako covered many forest types and in prehistoric times included vast areas of shublands. It is now known that the birds appear to feed heavily on shrubs and therefore they may do better on an island with regenerating shrubs than in an older tall forest. If possum and other browsers have depleted the present habitat of kokako then wouldn’t we expect them to use much larger areas and have greatly reduced breeding output?

The example of the saddleback, the other surviving wattle bird, is informative. Saddleback were also considered to be a bird of tall forests and to have an equally low breeding rate when they were restricted to Hen Island. When put on Cuvier Island with its regenerating shrub layers, saddleback laid larger clutch sizes, more than one clutch per year and lived in very small territories. When finally put onto Tiritiri, which had been considered unsuitable because of a minimal area of mature forest (less than 20 ha), some saddleback more than doubled their breeding rate compared to the already increased rate seen on Cuvier. How do we know that kokako won’t respond similarly? Kokako were present on Motutapu Island (1,500 ha) within the last 500 years and could probably survive on islands as small as 150 ha (early naturalists record them on islands of this size) with far less management than is currently needed on the mainland. Given the statement by the Recovery Group that many of the existing populations are probably doomed, and therefore birds from these populations may be available for transfer, shouldn’t a greater range of options be considered for kokako recovery including islands that have open public access? Another issue is cost. Given the urgency and seriousness of the conservation problems in New Zealand, which has as many rare taxa as the mainland United States, serious consideration of each programme’s cost effectiveness is needed.

The present cost of mammal control in mainland areas is often much higher than the cost of eradicating mammals from an island of similar size. Furthermore, mainland control must be repeated whereas the island eradication option is permanent. Current plans to eradicate mammals from Rangitoto and Motutapu Islands offer the potential to do more for kokako and rare species management than any of the existing programmes for kokako on the mainland. It will cost less, allow the return of kokako to part of their former range and provide access for more people to their natural heritage. In early years of recovery programmes when there is a high priority on building up numbers of individuals the cost of producing young should be considered. Rough calculations suggest that the cost of some mainland young in species such as kokako and takahe are considerably greater than the cost per bird of island-reared young. The research on kokako has given an excellent data base on the flexibility of kokako behaviour. The first three years of the programmes of "research by management" have also provided necessary information on the relative costs and benefits of different island and mainland options. For the benefit of kokako, isn’t it timely to stop, publicly evaluate all the existing information and with the help of people with a wider range of financial and advocacy expertise produce an updated plan? Doing more doesn’t mean more of the same.

But what will happen to the other kokako populations scattered around the North Island? Without management, and even with management, they are probably doomed. Their best chance and most useful role may be if they are transferred to an offshore island, or taken into captivity. A decade ago when logging was at its height in the Bay of Plenty, 34 birds were rescued before the forests were clearfelled and burnt. They were taken to Little Barrier Island where they have thrived, and today island-bred birds outnumber the immigrants. Kapiti is the next most suitable island for kokako. This summer five birds from the west Waitomo forests were captured and taken to Kapiti. Over the next five years fifteen pairs will hopefully be established on the island.

The South Island kokako

F THE NORTH ISLAND kokako has problems, they are nothing compared to those of the southern subspecies (Callaeas cinerea cinerea). One hundred years ago this bird, which is mainly distinguished from its northern cousin by its orange rather than blue wattles, was abundant throughout the South Island. Facing the same pressures of predation and habitat modification as its northern counterpart the bird declined rapidly in numbers during this century and many scientists have considered it extinct for the last 30 years. However, there have been enough unconfirmed sightings over that period from areas as widespread as Stewart Island, Nelson Lakes, north-west Nelson, Wakatipu Forest and Fiordland to keep alive the hope that this secretive bird survives in dense remote forests (see Forest & Bird May 1989). A feather found on Stewart Island in 1987 is the best evidence to date that the southern kokako is holding on. It was confirmed only last year after microscopic analysis at the University of Amsterdam that the feather did indeed belong to the South Island kokako and that it had come from a recently living bird. The chances of survival of this subspecies, however, must be considered pretty slim while the threats of stoat predation and competition from browsers for food continue.

KOKAKO '

Other lone birds or pairs may be taken into captivity at Mt Bruce Wildlife Centre. They will form the basis of a captive breeding population, another insurance against extinction and a source of study. SLANDS FREE of introduced mammals are havens for endangered native birds, and these island populations are an insurance against extinction. Compared with the relative ease of island security, mainland management of

kokako is difficult, time-consuming and expensive, and there is no guarantee it will save the birds from extinction in the longer term. So is it worthwhile? Why not take the easy option, save money, and rest on the laurels of Little Barrier and Kapiti Islands? Some scientists favour that option (see page 30) but Paul Jansen vigorously champions the recovery plan and its mainland programme. Until the research is done, the doomsayers’ opinions are premature and unwarranted, he says. He points out that at Kaharoa, where introduced mammals are controlled, kokako have increased to ten pairs with six young produced last summer, a significant increase over the previous summer’s numbers. Gerry McSweeney, former director of Forest and Bird, also argues stongly for mainland programmes. "Offshore islands usually have their own, often unique, assemblage of animals and plants which may be threatened by the introduction of ‘foreign’ species like kokako", he says. "They also provide little opportunity for ordinary people to participate in the conservation programmes or to benefit from viewing threatened or endangered species in accessible locations." As the results of the various studies come in, it may become apparent that management need not be comprehensive or regular. Perhaps control of key predators, in those fruitful years when kokako food is most abundant, may be enough to allow breeding and population stability. New technology may make pest control easier and cheaper. Island sanctuaries too are vulnerable. Catastrophes may occur. Fire, storm or rat invasion could overturn the island harmony overnight. Even if disaster does

not strike, this territorial species will need management to ensure its long-term survival on an island of only 3,000 hectares. There had been no kokako on Little Barrier Island for thousands of years, suggesting the island may be too small for them to survive naturally over a long period. Kapiti Island, at 2,000 hectares, is even smaller. The position of the kokako recovery group is clear — don’t put all your eggs in the basket of island sanctuaries. Their philosophy is optimistic. They believe that, with good management, the North Island kokako will recover from its cen-tury-long decline. A depressingly large number of New Zealand’s threatened birds are now restricted to offshore islands, inaccessible and invisible to most people. Against the odds the kokako survives on the North Island. For the sake of the birds themselves, their part in the forest ecosystem, and the people of New Zealand, let us try and keep them here. Acknowledgements Thanks to Ann Graeme for additional information.

Gretchen Rasch has been involved with kokako since 1985. She works in the Threatened Species Unit of DoC and is the author of the kokako recovery plan.

She is currently based in Te Anau. eS

On his farm north of Rotorua, Forest and Bird member Winston Fleming has placed a covenant on 30 hectares of native bush adjoining the Kaharoa forest. Kaharoa is the site of a kokako research programme sponsored by Tasman Forestry. Since the bush was fenced to keep out grazing stock, the understorey has flourished and a pair of kokako have taken up residence. Winston calls his venture the Kiwi Outback Experience and guides visitors through the forest or provides billy tea and venison at his bush hut where guests can enjoy the bird song at dusk. Prospective visitors can contact Winston on (07) 332-3629.