NORTH ISLAND KOKAKO

Forest and Bird, Issue 282, 1 November 1996, Page 12

NORTH

ISLAND

KOKAKO

and

SUE MOORE

JOHN

J es Po t kokako: the" ic forest birds, G warely surviving in its North Island forest fal’

he sanctuaries. Today, as

describe, much more is known about the

>? . i te kokako, and innovative research Rew ia management techniques have’made the bird's future on the mainland considerably brighter. &. i

ARLY MORNING in the King Country, conservation officer Phil Bradfield leads a sleepy group up a winding clay track through the bush. The party stops at Bradfield’s request, its members happy to catch their breath. A pause and a tape starts, sending the organ-like notes of a kokako out across the misty valley. The group listens, hearing only the call of the bellbird, then the real star of the show responds. Hesitantly, hopping through the branches of a tall tawa tree, calling softly, is Barley Magrew, one of Mapara’s 100-plus kokako. Close behind him his mate Mohawk.

How is it that these beautiful birds survive and are increasing in this mainland reserve, while the kokako’s two close relatives, the huia and tieke (saddlebacks), have either disappeared for ever or are restricted to offshore islands? The story starts here, in the King Country. In the 1970s, public concern about the logging of ancient podocarp forests and its effect on the endangered North Island kokako was increasing. Fundraising by Forest and Bird members paid the salary for a young scientist, Rod Hay, to study the behaviour and ecology of kokako in

the cutting edge

King Country and Bay of Plenty forests. Hay’s three-year study, and that of his Forest Bird Research Group colleagues, found that kokako populations were declining due to loss of habitat, and perhaps competition and predation from introduced mammals. Eventually public protest stopped logging in most of the North Island’s indigenous forests — but still the kokako populations declined. The bird’s habitat seemed safe but some other agent or agents in their forest homes was affecting its survival. A kokako workshop in 1988, convened by the newly formed Department of

Conservation, looked at ways to reverse the decline. It was at this key meeting that the now famous Research by Management concept was first discussed and agreed upon (see box page 15). A recovery plan involving a "recovery group" of key people with specialist knowledge of kokako was also developed. Completed in 1991, the plan became the first in New Zealand for a threatened species (see article by Gretchen Rasch in Forest & Bird May 1992). O SAVE THE kokako, managers ; first needed to know what was causing the decline. Why were kokako populations continuing to decrease in large unlogged forests such as national parks? Predation seemed likely, but who were the predators? Were the birds too old and just not trying to breed? The work of Rod Hay and others provided another suggestion. An extensive dietary overlap was discovered between possums

and kokako and it seemed that kokako populations had decreased in forests as possum populations increased. Perhaps competition with introduced browsers was causing food shortages for kokako? Guided by the 1988 workshop, Landcare Research and DoC quickly embarked on two ambitious research programmes. In one, kokako breeding attempts and their outcomes were closely monitored for four years at Rotoehu in the Bay of Plenty where mammal pests were abundant. The second, the Research by Management programme, compared the breeding success and adult density of kokako in Rotoehu with that in two other forests — Mapara and Kaharoa — where introduced pest mammals were controlled. At Rotoehu, most pairs (60 to 70 percent) attempted to nest each year with the same pairs trying each year. While researchers were checking to see if there was a difference in weight between breeding

and non-breeding pairs (which might have indicated food shortages) they got an unexpected surprise. There was no weight difference, but in non-breeding pairs it appeared (from leg measurements) that both birds were males. Little wonder that

these pairs weren’t attempting to breed. Sadly 83 percent of the Rotoehu nesting attempts failed, mostly due to predation at nests. The innovative use of video cameras revealed the culprits as ship rats, possums and harriers (see box page 17). This explained the low success of breeding attempts and probably the malemale pairings — loss of females on nests was causing an excess of males. The identification of possums as nest predators was startling. Additional evidence came from the distinctive feather pellets that possums spat out after being fed

road-killed birds. These pellets matched others found after predation of kokako adults and chicks. This was exciting news for all involved — possums were kokako predators as well as competitors. Possums and ship rats were part of the suite of introduced mammals being controlled in two of the Research by Management blocks. Would their control halt the kokako’s decline in the managed blocks? The answer was yes, but it didn’t come straight away. After three years of management the kokako population at Kaharoa

Kokako facts

North Island kokako Callaeas cinerea wilsoni is one of three members of the ancient New Zealand wattlebird family. Of the other members, the huia is extinct and the saddleback is confined to offshore islands. | bird of unmodified lowland forests, particularly mixed hardwood, podocarp and kauri forests. 38 cm long; a weak flyer with a rich flute-like song. mainly vegetarian: a wide range of foliage, flowers and fruits, and sometimes small insects. total numbers around 1,000 in scattered populations; as an inhabitant of dense forest interiors, its decline was not widely noticed until the 1970s. South Island subspecies Callaeas cinerea cinerea (distinguished by orange rather than blue wattles) not been sighted for many years and is presumed to be near extinction (see page 6).

(also in the Bay of Plenty) had the same high chick output as Little Barrier Island’s and in 1992 it was the only mainland kokako population known to be increasing. The proportion of the population in pairs increased from 64 percent in 1990 when management started, to 100 percent in 1993, and the number of pairs more than doubled. In 1993, management at Kaharoa was switched off to see if chick output would decline as rat and possum numbers increased. It did, and last season (1995-96) no chicks fledged at all. In the other managed forest of Mapara, in the King Country, there was little obvious success at first. Kokako numbers actually fell in the first two years of management and it seemed that only a handful of pairs were actually trying to breed. On the surface things were grim but DoC’s Te Kuiti Field Centre staff persevered, encouraged by the success of a few successful pairs. Slowly the investment began to show returns. In 1990-91, five birds fledged, then seven the following year, then 15 more... Fledgling survival, at 80 to 90 percent, was remarkably high,

Research by management the way of the future

NDER "Research by Management" (RbM), management procedures are used experimentally to test an idea. All it takes to combine management with research is to use standard, reliable methods to monitor the outcome of the management action. With North Island kokako, two treatment blocks — Mapara and Kaharoa — were subject to "maximum practicable" control of pest mammals (goats, pigs, ship rats, possums,

mustelids and feral cats). In another, nontreatment, block — Rotoehu — pests were not killed. The kokako and pest populations were monitored in the same way in all three blocks. RbM is special because it allows us to get on with managing systems while studying and learning more about them. It also combines the strengths of conservation managers and scientists to produce reliable scientific knowledge about the causes of kokako decline, while at the same time protecting kokako populations.

Who dunnit?

N THE UNMANAGED forest of Rotoehu, 60 to 70 percent of kokako pairs were nesting each year, but most attempts were unsuccessful. To find out what was happening at the nests, researchers put 19 nests under 24-hour infrared video surveillance. The cameras revealed the eating of eggs by ship rats, and of eggs and chicks by possums and harriers. Occasionally ship rats and possums were beaten off nests by protective females, or did not attack chicks when they had the chance. Nests often received visits from more than one predator, leaving a confusing trail of evidence behind. One month of video surveillance at a single nest revealed this sequence of events: @ seven rat visits (all fought off by the female), @ a possum visit (it didn’t eat the chicks for unknown reasons), @ two more rat visits, @ a harrier attack — one chick was eaten, the other jumped out of the nest and later died on the ground, @ two scavenging visits by rats that night, and finally

@ a second scavenging visit by a harrier the next day. Even in areas such as Mapara with intensive pest mammal management, a

few kokako eggs and young disappear without trace. It is hoped that video surveillance of nests will continue to help solve these mysteries.

the new recruits were soon forming new breeding pairs, and after three years the population decline was reversed. By the 1994-95 summer, 18 breeding pairs were established and it seems that the copious forest fruit production of the preceding spring triggered an overwhelming breeding response. That season for the first time on record, all kokako pairs that attempted to breed were successful, half of these went on to fledge two broods of chicks, and one even fledged three. A stunning 54 fledglings nearly doubled the population and a community of birds in decline had now been truly rejuvenated. Careful research on banded birds by Ian Flux (the current recovery group leader), Phil Bradfield and others suggests that the slow start at Mapara was, as at Rotoehu, due to a shortage of females and that 75 percent of pairs were male-male. The number of male-female pairs has increased sixfold to 29 since management started in 1989, thus hugely increasing the reproductive potential of the Mapara population. In 1994-95, as a treatment switch in the Research by Management experiment, pest control was initiated at Rotoehu. That season 40 percent of monitored pairs fledged young, the highest recorded in the five years of study there. This soared to 66 percent the following (1995-96) season, when pest control was more effective, and

island transfers

HE SUCCESS OF kokako management on the mainland is good tonic for New Zealand conservation. However island strongholds still have a key part to play in the kokako story. With present technology, mainland areas will always require management to keep pest numbers low. On offshore islands, once pests have been eradicated, it is far less likely they will reinvade. In the 1980s, the first new island population of kokako was established on Little Barrier. The first Little Barrier Island kokako were rescued from central North Island forests that were being felled. The birds have done well in their new home, and have a high chick output. In 1994 the last Great Barrier Island kokako were transferred to Little Barrier. It is hoped that the two birds will find mates and perpetuate their ancient and possibly unique bloodline. Another island population is being developed on Kapiti Island. Initial attempts at populating the island used single birds — remnants of old populations. After years of isolation, these birds didn’t respond well to taped calls and were difficult to catch. Besides they are apparently mainly old males — not an ideal start for a new population. More recently, kokako from Little Barrier Island and captive-bred birds from Mt Bruce Wildlife Centre have been released on Kapiti. At present there are still few breeding females on the island. DoC now plans to transfer some of Mapara’s "teenage" females to get

the Kapiti population firmly established. The next island in the queue is the recently revegetated Tiritiri Matangi. It is likely that birds from Mapara’s growing

kokako population will also be used to establish this new population. It will be interesting to see how kokako react to the dense young plantings here.

hopes are high for even better success in the coming season. The success of kokako research and management is a tribute to the effectiveness of the Kokako Recovery Group. "The group’s success is really due to two things," says Paul Jansen who led the group from 1992 to 1995 and who now heads the Kakapo Recovery team. "First, the whole programme has a very sound scientific basis with realistic objectives. Second, we made a real effort to be inclusive and involve all the field people who are directly involved with the birds. This pays huge dividends since everyone knows what is going on and is more enthused about the recovery process." OST REMAINING kokako forests are now being intensively managed to protect their precious inhabitants. The Research

by Management experiment isn’t over yet but the preliminary results have already helped wildlife managers. We now know what is causing the decline (mainly ship rats and possums) and how to reverse it (control them to very low levels). Management techniques are constantly being refined. The survival of kokako in the North Island to the present day indicates that annual pest control is unnecessary to maintain populations of such a long-lived bird. At Mapara, formal Research by Management will finish after one more season but management will continue. DoC will now turn off much of the pest control for a few years. This "pulsing" will give the Mapara forest a rest from the heavy poison use of the last six years and allow DoC staff to work on other high priority projects. Intensive management has now started

in Northland. In the swamp maire and damp ridge forests of Mataraua, bait stations and leg-hold traps are being used to reduce ship rat and possum numbers. Three pairs of kokako nested last summer, successfully raising four to six chicks. At Trounson Kauri Park a new kokako area is being created. DoC staff hope to "mop up" isolated Northland kokako and move them here to a new safer home. So far two kokako have been transferred and are being monitored; more transfers are planned. Other threatened native species such as kiwi and kauri snails will also benefit from the intensive mammal control underway in the park. In Auckland, DoC and the regional council are working together to protect kokako in the Hunua Ranges. Council resource scientist Brenda Greene says that in recent seasons only one of the five pairs that are currently being protected has been

recorded breeding. It may be that only one female remains in the population. "DoC’s now got funding to band the birds this season; that'll be a really significant step," commented Greene. "In five years weve gone from having no management in the Hunua Ranges to one of the most intense management regimes you can have." In the early 1990s, Whakatane DoC contractors Jeff Hudson and Grant Jones surveyed most of the northern half of Te Urewera National Park for kokako. They covered around 60,000 hectares, mapping the birds and developing a new kokako survey method as they went. Their work revealed that Te Urewera, with at least 600 birds, is home to more kokako than the rest of the North Island in total. But even here, in the largest remaining chunk of North Island kokako habitat, numbers are declining. A survey of Te Ikawhenua Ranges in 1993 counted 187 kokako; a return trip in 1995 found less than 50. Pete Shaw, manager of the new Te Urewera mainland island project, says the

kokako decline mirrors the arrival of possums in the area. Shaw, Hudson and Jones have instigated predator control to protect the remaining birds in key areas, and they are hopeful that kokako productivity and survival will increase this coming season. Back in the King Country, local members of the New Zealand Native Forest Restoration Trust and the Otorohanga Zoological Society are protecting 650 hectares of Mangatutu forest (in north Pureora) and last season witnessed the successful fledging at least ten kokako chicks. Nearby, in the Waipapa Ecological Area of Pureora, DoC has set up another protected area. Monitoring and protection here are being specifically designed not just for kokako, but for a range of threatened species, including Dactylanthus and kaka. E.:: THE EARLY days, the kokako work has been relatively well funded, due to high public interest, support from the top levels of DoC and

generous corporate sponsors. Tasman Forestry funded pest management and monitoring at Kaharoa during 1990-1994 and, now, State Insurance and Norwich Union Ltd actively funds many aspects of kokako management through the DoC/Forest and Bird Threatened Species Trust. This sponsorship provides funding for the recovery programme including video surveillance at nests, the reintroduction of kokako to Trounson Kauri Park and monitoring of Kapiti Island kokako. "It’s a win-win situation," says the general manager of State Insurance, Malcolm Hill. "Our sponsorship helps the kokako, helps New Zealand’s environmental future, and hopefully gives us some positive publicity." Unfortunately for some North Island kokako populations, the management has come too late. Kokako populations in Taranaki, Whanganui, western Waikato, the Coromandel and Great Barrier Island have already dwindled to extinction or a handful of single birds. Some of these birds have been transferred to offshore islands (see box page 18). Others remain, alone in their ancient territories, sad vestiges of what were once thriving populations.

HAT LIES AHEAD for the North Island kokako? We’ve won some of the battles, but what about the war? Over the next year a revised recovery plan will be written. Managers are now confident that they can protect kokako in medium-sized (1,000 to 3,000-hectare) blocks. The recovery group is looking towards sustainable management for much larger areas and longer time periods. Future research and management will look at sustaining kokako over tens of thousands of hectares in the few remaining very large forests, especially Te Urewera. Eventually places such as Whanganui, from where kokako have disappeared, may again be home to this charismatic songster. Whatever happens, the commitment and enthusiasm of the many people involved in kokako recovery has always remained high. Many early workers of ten to fifteen years ago like Rod Hay, Hazel Speed, Phil Bradfield, Gretchen Rasch,

Rhys Buckingham, Dave King, Dale Williams and Alan Saunders are still involved. Forest and Bird remains actively supportive and currently administers the kokako Threatened Species Trust. Finally a huge debt is owed to the many dedicated field staff who have painstakingly undertaken pest control in these mainland restoration projects. The future is looking brighter for Barley Magrew, Mohawk and other North Island kokako. ®

Sue Moons is completing a post-graduate Diploma in Wildlife Management, on study leave from DoC’s Te Kuiti Field Centre. JoHN INNES is a scientist at Landcare Research, Hamilton. He is scientific coordinator of the

kokako Research by Management programme, and was a founding member of the recovery group.

[RATS (% TRACKED), POSSUMS (PER 100 TRAP NIGHTS)) SHIP RATS POSSUMS 90-91 92-93 _ 91-92 MANAGEMENT ENDED 93-94 94-95

Ship rat and possum abundance at Kaharoa, during management and once management had ceased. During the period of management, both ship rats and possums were kept to low numbers. Once management ceased, rat numbers increased immediately and significantly; possum numbers also increased, but more gradually.