Issue 3 Winter 2005 RDI Great Barrier Island, Ph: (09) 4290 414 GBI Environmental News

The publication of the Great Barrier Island Charitable Trust, whose trustees are: John Ogden (Chair), Tony Bouzaid, Jude Gilbert, David Speir, Liz Westbrooke, Fenella Christian (Secretary)

Lord Howe woodhen - Photo: Ian Hutton Profile: Lord Howe & Magnetic Islands Predators — Introducing your Own Trapping Analysed at Windy Hill

Mission Statement: To sustain and restore the cultural and natural environment of Great Barrier Island in order to enhance the native biodiversity and foster the socio-economic well-being of the people. leading the way

If the community embraces the idea of a predator free island, the Great Barrier Island economy will benefit from a unique eco-tourism opportunity as the restoration of the biological diversity of the native flora and fauna becomes nationally and internationally recognised. Perhaps the island could follow the proactive conservation stance taken by Lord Howe Island with its World Heritage status. They have now eliminated , goats and feral cats and are currently planning total rat eradication. Domestic cats must be neutered and no new cats brought in. Visitors are limited to 400 at one time. Just 11 by 2.5 km, Lord Howe has the same spectacular scenery that we see here and although politically Australian, it is biologically more closely allied to New Zealand (1000m beneath the surface both Nor- folk and Lord Howe are part of the sunken continent of Zealandia). However it has lost almost all its endemic . The following article is from Ian Hutton, a naturalist working there and explains more about their projects

n 1979, as part of a program to they are living within the settlement 1 rescue the Wooden (a small area. Not only has this made the flightless about the size of a Island a safe environment for the Weka) the Lord Howe Island Board Woodhen, but other birds have completed a project of trapping and greatly benefited. Little shearwaters, removing feral cats from the Island. once plentiful on the island, were In 1982 the Board placed a ban on forced off by cats a century ago, but domestic cats as pets, with a have now started breeding back on grandfather clause whereby people the main island again. Other seabird who had pets could keep them if numbers have increased on the Island desexed, but no more to come onto Sooty terns and Wedge-tailed the Island, and they have gradually all shearwaters are breeding in bigger disappeared. numbers each year. Seabirds are one This, plus removal of feral pigs and of the major tourist draw cards to control of dogs has made it possible Lord Howe Island. for the numbers of the Woodhen to In 2000 the New Zealand company recover from 20 to around 250, and Prohunt were contracted to remove

1 Photo: Ian Hutton Palm seed hulls. Rat foraging has a significant effect on the economics of the island palm industry. feral goats from the Island and now all that remains in terms of introduced pests are and mice. The Photo: Ian Hutton Lord Howe administration and the Rats are next on the list of introduced community are aware of the social, predators targettedfor eradication. economic and environmental costs of these pests and have had New native plants; seabird and landbird Zealand experts do a feasibility study numbers would increase; the native to investigate the possibility of rodent gecko and skink would increase from eradication. The Board is currently rare to abundant, and numbers of liaising with organisations in New endangered invertebrate such Zealand with the view to trialing a rat as snails would increase. Also there specific poison being developed. If are several invertebrates that rats this new technology is successful, it have removed completely from the would remove the potential non target main island and only survive on species impacts associated with offshore islets; when rodents are current traditional rodent eradication eradicated these can be brought back operations. to the main island. The cost benefits to the community Proposals to remove cats and goats would be a huge saving in poison was a little bit controversial with program costs, an increase in revenue some sectors of the community, but for the island palm industry, no loss now everyone can see the huge of vegetable and fruit crops, and benefit of these moves. No one would elimination of health risks associated argue with the benefits of removing with rodents. rodents, so hopefully, with help from The environmental benefits would the Kiwis, Lord Howe Island will be even greater — rats would not be soon become a haven totally free of eating seeds, stems and roots of introduced animal pests. 2 renewing or Editorial • by David Speir in fact self-managing resources. Conservation equals custody, husbandry, protection, WE LIVE IN A NATURALworld, safe-guarding, economy.In our dependentupon it for air, water case the ecosystems we are and food. This is true whether our looking to conservatively manage sustenance comes from the require considerable repair. kitchen garden or the super- Restoration comes before market. conservation. Its coalface ethos Early settlers on CBI found a deals first with the principal forested land,trees in excess, and agents of abuse. seemingly unlimited marine bounty. On CBI landmass humans no A natural world in which they were longer occupy that position, that their own masters. Survival was belongs to the introduced predicated on exploiting naturally mamalianpredators. Rats, feral occuring resources. cats, rabbits and pigs continueto A look back in Aotea's history impact on endemic species. shows a pattern of demand As the land of the old Great followed by extraction followed by Barrier sells, it does so at a price depletion - tall timber, gold, that inevitably brings in newblood copper, whaling, cray and fin - new values, new notions of what fishing. Profits from these the responsibilities are of holding activities mostly went elsewhere. land with high natural vlaues. Farming the marginal land on Change is in the air - morethan Aotea produced diminishing 60% of private land on CBI is now returns as fertility declined. held in offshore hands. The view Even when it is apparent that a looking in is quite different from process is failing we are naturally ours looking out. Many are recog- resistant to change- repetition of nising what we have here - a the old ways is the easier track to potential island ark. follow. Do we have self-sustaining New ideas require new grooves resources that could be used to be cut - not always a rather than abused; nutured into comfortable process. And it is resilient health and managedfor easier to oppose change than be the economic and social benefit of open to new outcomes. the Island residents. We think so. Conservation in its essence In an endeavour to gain offers new outcomes. However the inspiration from what others have word has become a loaded term - achieved faced with similar conjuring up images of high- situations, this edition of CBI handed Government actions and Environmental News looks outward regulations seemingly insensitive from our Island at conservation to the smaller scale of life; initiatives nationally and Yet by definition conservation conservation successes on other is basically careful use of self- islands. 3 REPORT TO THE BOARD by Tony Bouzald Magnetic Island Manages its Moggy's n August I spent a week's holiday opportunity to review the paper, 1 on Magnetic Island off Townsville survey and analysis but have had to on the Queensland coast. This pro- write to the CEO of the Council for vided the opportunity to look at the permission to obtain and utilise the results of the Cat Management Plan report. introduced there in 1997 subsequent The results over the four years have to a survey conducted in 1995. been spectacular. In the whole week I The principal ingredients of the was on the island I only saw one cat Plan were; and that was on a resident's property Council funded an initial during the day. The demand for microchip implantation of all resident's cat traps has decreased to domestic cats on the island. almost zero and apart from a constant [While this was not compulsory presence at the refuse tips the Council any cat caught without identi- and National Park only trap as a fication would be considered a result of sightings or cat sign. stray and put down] The report highlights a growing • Residents were supplied with cat problem with domestic dogs, traps on demand for trapping on particularly for ground nesting birds. their own properties As a result of this and the work • Council began an intensive carried out by DOC on Great Barrier trapping regime on land owned or illustrating the same problem it is administered by them, important to incorporate dogs into the particularly the refuse tips survey so that it is not specific to cats. • All domestic cats to be spayed Working backward from the 1999 other wise if caught will be culled Magnetic Island survey will ensure At the same time the National Parks that our first survey asks the right staff started trapping along the tracks questions. This way when a follow up in the National Park which makes up survey is conducted there will be 70% of this 5,000-hectare island. comparative information for analysis. In March 1999 the Townsville City Enlarging the parameters of the Council conducted a follow up survey to include questions concern- survey on the attitudes of the resi- ing dogs will provide a good sense dents after the Plan had been in place for attitudes of the Great Barrier for 2 1/2 years. This subsequently public. As a result of the change it became the subject of a paper presen- will be appropriate to leave the ted at the Urban Animal Management suggested changes to the dog by-law National Conference on the Gold until the results of the survey are Coast in August 1999. I have had the available. 4 Introducing our own predators ative to Africa and Eurasia sites and the subsequent, and the intermittently unwittingdegradation of this connected Americas, cats and character by those who pay so dogs are alien species in Austral- much for it. asian and island eco-systems. In Under the Resource Manage- New Zealand when we choose to ment Act, some district plans now live with these com-panion seek to prevent scorched earth predators, they will inevitably developmentby prohibiting the prey upon the native wildlife. clearing of remnant stands of What wildlife, you mayask, as native trees, wetlands and you shift into an established estuarine fringes. This is a great suburb? Indeed, to provide for step forward. But noneof the our lifestyle we have usually so plans have yet addressed the issue altered the natural environment of protecting the inhabitantsof that most of the native plants and that vegetation — the wildlife animals have been removed. The itself — from this continuing domestic cat and dog is often the colonisation.With every new only link to the animal world left household there is an implicit to a city dweller. permit to bring in cats and dogs But coming here to CBI you are that kill native fauna, and to entering a world of both old and introduce garden plants capable of new: houses sit alongside complex invading native vegetation and habitats — stream margins or reducing its value for wildlife. dune systems — where small It is a bold newmind set to populationsof birds and reptiles suggest that, in some com- have existed for centuries; munities, people might live in lifestyle blocks sit amoungst old greater harmony with nature growth forest and cottages near without the ubiquitous cat and rocky shorelines. Because CBI has dog. avoided some of the deadliest GBI does not have to look introduced predators we have further from NZ for examplesof remnant poulationsof threatened conservative governance with ducks, ground and shore birds, regard to introduced pets. reptiles and invertebrates in There have been recent plan- these very habitats — vulnerable ning decisions controlling or to these aliens banning pets where new subdivis- As this newwave of city ions are adjacent to ecologically workers, striving to re-establish sensitive areas or to populations links with the natural environment, of threatened native species, emigrates to locations with Wellington City Council, already natural character, there is an firmly established on the world- irony in the demand for these wide conservation map with the 5 Karori Sanctuary, has allowed a At present on CBI we have no 104 unit subdivision on the old eco-subdivisions of this type, and railway settlement landat attitudes to wanderingdomestic Kaiwharawharawith a cat-free animals vary considerably between provision. This zone of regener- communities on Aotea. ating bush is an important bird The Petscan 2000 survey corridor into the city from the provided some idea of local north and by designating this opinion.The professionally subdivisioncat-free the council analysed findings indicated: has recognised both the impor- 1. Support for both cat and tance of the avenue and the dog management plans ability of domestic cats to wreck 2. Nearly half had experienced havoc on the native bird problems with wandering dogs populations moving through and 3. Pet cats were acknowledged residing in the area. as roamingbird killers but valued Evidence for this stance came for their perceivedratting from an 84 day trial run jointly by abilities. Forest & Bird and DOC to find out 4. Manyresidents experienced what Wellington cats kill. The rat damage to property and trial showed the average domestic environment. cat killing at least 8 birds per Although it is obviouslyeasier year and only two rats. Given the to define pet ownershipconditions numbersof cats this predation from the outset (for example in a has a devastating effect on our newly formed subdivision) there is slower breeding native birds. considerable sympathy for the A wildlife friendly covenanton concept here. There is obviouslya the Opara Estate subdivisionin significant section of the CBI Northland not only protects the communityfor whomconservation area from invasion by domestic value is a major factor in their pets but actually defines the kind residence. It is also acknowledged of person who buys into the area. the role domestic pets play as This kind of protection will in time social companionsin isolated add value to the land as protec- situations. tion of this kind is more sought Aotea is under scrutiny as it is after by prospective buyers. scoped for possible kiwi intro- Development of a subdivision on duction, further introduction of a peninsular of land surrounded by threatened species and possible saltmarsh and mangroves near predator eradication in the Athenree in the western Bay of future. Plenty is conditional upon a The issue of domestic pets is domestic cat and dog ban pro- clearly in the spotlight. posed by Forest & Bird and supported by the District Council. Edited by David Speir with extracts The developer is currently appeal- from Forest d Bird's: "Eco-Subdivisions ing the ban in the Courts. - Living without cats and dogs". 6 An analysis of rat trapping results byJohn Ogden on Little Windy Hill

Windy rT*he Hill Rosalie Bay so: Fig I shows that the initial trapping 1 Catchment Trust (WHRBCT) has at Windy Hill (1999) had higher catch reently completed an analysis of their rates, while Fig 2 suggests that current rodent trapping programme l , which was catch rates at Windy Hill are started in 1999 and has increased in significantly lower than in equivalent etTot1every year since then. The vegetation types at Awana. analysis also includes comparisons with Unfortunately there is uncertainty in results from Benthorn Farm (BT), both comparisons, because different Awana (Awana Catchment Trust) and numbers of traps were used over Okiwi (DOC data). The results are different periods. All the results show sobering. the same seasonal pattern for ship rats, The most intensive effort has been at with a peak in March/April and a low in Windy Hill and Benthorn farm, where the late winter (Fig 3). It is important to in 2004 c. 1800 traps caught c. 3400 have established the Island-wide rodents over c. 260 ha. That represents generality of this pattern; it proves that c. 13 rats per ha per year. We hope this changes at any one site are mainly a apparently low catch rate is because result of births and deaths, not migrat- numbers have already been reduced by ion to or from the area. The last few five years of trapping. This is probably years of intensive trapping at Windy

(a) Rodent indices at WH 1999-2001 20 18 16 14 12 10 8 6 4 2

Date

Figure l. Rodent indices at Windy Hill, showing the initial decline in catch per 100 trap-nights (an index of rat abundance). 7 RAT INDICES AT AWANA AND LWH 45 40 35 30 FOREST at AWANA 25 —H—SCRUB at AWANA 20 15 WINDY HILL x 10 10 5

MAR SEP MAR SEP MAR SEP MAR 01 01 02 02 03 03 04 DATE Fig 2 - comparisons between rat abundance in native forest and manuka scrub at Awana, and a mixture of these vegetation types at Windy Hill. Note that the Windy Hill results have been multiplied I Oxto get them onto the same scale - ie. there are almost I Ox fewer rats in similar vegetation types at Windy Hill.

(b) Benthorn farm 2002-2004

2.500

2.000

x 1.500 Mice u Kiore —„—ShlP 1.000

0.500

0.000 Jan- May- Sep- Jan- May- Sep— Jan- May- Sep- 02 02 02 03 03 03 04 04 04

Fig 3. Rodent numbers (catch per 100 trap nights) at Benthorn Farm over 3 years, showing the seasonal pattern and the way the peaks in Kiore and mice numbers generally set off from the peaks in ship rat numbers (a month earlier or later). 8 (c) Ship rat index v. Number of traps Windy Hill (LWH) and Benthorn (B) combined April and September 2002-2004

2.s

2 •April LWH • Sept WHH 1 •April B • Sept B 0.5

o 200 400 600 800 1000 1200 1400 Nurnber of traps

Fig 4. Ship rat indicies at April peak (squares) and September troughs (diamonds) versus number of traps used, showing that increasing trap numbers reduces the late summer peak (slightly) but not the late winter low point.

Hill have apparently reduced the April elsewhere in New Zealand, seem to be peak. but the overwintering population the only alternative. remains unchanged (Fig 4). From the perspective of an Island- As the vegetation recovers from wide eradication campaign in the future formerly higher levels of rat predation, the results are very useful. Extrapola- there is an abundance of food (eg nikau ting, it would require an army of over berries, invertebrates). Consequenly 400 people and c. 200,000 traps to any relaxation of trapping effort is achieve the results at Windy Hill overall likely to result in a rapid rebound in rat —results which are probably the best numbers. Moreover, recent work with achieved anywhere with traps alone, but 'tracking tunnels' suggests that the rat which we now know are not good population at Windy Hill is greater than enough. We know too that different the trapping results suggest. Up to 49% vegetation types have very different of 120 tunnels were visited by rats in absolute numbers of rodents, and October 2004, when rat numbers should different proportions of ship rats, kiore have been minimal. Perhaps the trap- and mice. Land Units 8 and 9 (tea-tree ping has gradually selected a trap-shy on slopes and eroding ridges) which rat population. Whatever the explan- cover wide areas on the Island, have ation, the 'tracking tunnel' results are relatively low ship rat numbers; not good for robins, and show that streamsides and coastal flax have most. trapping alone is unlikely to get rat Kiore are commonest at grassland/scrub numbers down sufficiently for eco- boundaries. We know in fact where system restoration. Poisons, proven to rodents are and when they are at their work in rodent eradication programmes Continued on page 10 9 Mohunga Project Update by Colin Griffiths THE MOHUNGA Project has made some steps toward eliminating predators from the peninsular. The publicationof 'The Ecological Restoration of Mohunga Peninsular' by Wildland Consultants that describes the 3 biodiversity of the area and outlines possible directions toward our goals is an important alongthe spine of the peninsular document upon which wise has enabled better access to all decisions can be based. It ridges and spurs. This is a beauti- recognises that there are many ful walk with panoramicvistas of threatened flora and fauna that Aotea and the Gulf. would benefit from the total As with any other projects like exclusion of predators. The this, much of the hard grind is report recommendsthe most carried out by dedicated effective way to accomplish this volunteers. Many hours and much is by meansof a predator-proof sweat have all ready been spent. fence. The project now has a Vehicle' A grid of tracking tunnelsand to move forward with in the form bird count sites has been set up of an incorporatedsociety, The covering the range of habitats. MohungaRestoration Group Inc. This will furnish us with data to This, with charitable status, will help determine the effectiveness make the soliciting of funds of predator control. easier, we hope. Re-openingthe old bridle track Dollars make this corner of the World turn too. From page 9 most vulnerable. We have good The basic research is not complete, but I indications of 'interactions' between the believe we now know enough about the different species, and can anticipate an enemy to start planning the campaign. increase in mice if the rats are removed. I Copies available from Judy Gilbert on request. 10 The GBI Environmental News is the publication of the GBI Charitable Trust Contributions are welcome provided they are supplied as E-Mail or as Microsoft RTF or ASCII files. All material published should be regarded as being protected by copyright legislation and cannot be reproduced withoutthe prior consent of the publisher. The Trust reserves the right to publish and/or edit material and takes no responsibility for errors or ommissions in transcripbon. Address to [email protected], indicating content of file attachments and providing a contact telephone or E-mail address. Photo: John Speir

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