Rats

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In August 1903 eminent naturalist Henry Travers wrote to the Colonial Secretary Sir Joseph Ward about “Reserves for Scenery and Native Birds, etc”. Travers had seen first-hand the formerly abundant birdlife on  Takapourewa (Stephens Island). But “a year or so later cats were introduced; I was there a few weeks ago, and there is not a native land bird left on the island in consequence of the depredation of the cats”. Of course the loss of birds included the extinction of the Stephens Island wren.

Takapourewa is in the middle distance to the north of Puangiangi and the Rangitoto group. Henry Travers went on to say “I also venture to suggest, that a number of the Tuatara lizards (from Takapourewa) be placed on the two Rangitoto islets on which there is bush; this would prevent any possible chance of their becoming extinct in this portion of the Colony”.

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Document courtesy Dr Colin Miskelly, Curator of Terrestrial Vertebrates, Te Papa

Travers showed insight into predator-prey interactions at the turn of the 20th Century or earlier, and advocated removal of pigs, goats and cats from Kapiti before it was used as a bird sanctuary. His suggestion for the Rangitotos to be a tuatara sanctuary might have been forlorn though, as they were certainly already carrying rats.

Rodents and mustelids and possums took a long time to be recognised as pre-eminent causes of decline and extinction of New Zealand’s native birds, lizards and invertebrates. Elsewhere in the world habitat loss is often key. There, birds and mammals for example have co-existed for millions of years and the birds have evolved to cope with mammalian predation. Not so on our small piece of Gondwana, yet even today those only peripherally interested in conservation, and those with agendas that it suits, stick to the notion that things will be all right if only the forests are protected from destruction.

Ninety-five years after Travers speculated that the Rangitotos might become a sanctuary for tuatara, Nicky Nelson from Victoria University and Peter Gaze were on Takapourewa. Nicky was doing a PhD on the induction of eggs from gravid tuatara and their incubation back in the lab, to better understand the role of temperature in determining the sex of the hatchlings.

Nicky and Peter discussed how the 400 young tuatara resulting from Nicky’s work could best be used to establish a new wild population. She pointed (quite possibly from the same spot as Henry Travers) to Wakaterepapanui, the northernmost of the Rangitotos some 10 km to the south, remarking on what ideal habitat it would be. The problem was that Ecology Division of DSIR had found that Norway rats were present on all three islands and Tim Markwell (Victoria University) had more recently confirmed the presence of kiore on Wakaterepapanui. These rats would prey on tuatara eggs and young as well as out-competing them for invertebrate food.

Norway rats and kiore do not co-exist easily and it is tempting to think that kiore were once widespread on all three islands, but that Norway rats were introduced to Tinui after European colonisation and gradually swam to the northern islands, replacing kiore in the process.  Were the few surviving kiore on Wakaterepapanui evidence of more recent colonisation there by the Norway rat? Possums and ship rats were fortunately absent, and there have been only two records of single stoats from Puangiangi. Stoats, present on D’Urville and within theoretical swimming distance, are efficient predators of Norway rats, and the presence of the latter therefore indicated that stoat invasion was rare and that they had not bred on the islands.

If the potential of Wakaterepapanui to house tuatara was to be realised then the rats had to go, and from all three islands to prevent re-invasion one to the other. This was feasible given the wins already had with aerial brodifacoum by the late 90s, but it was relatively expensive. The consent of three different landowners would also be needed. Wakaterepapanui is publically owned and managed by the Department of Conservation. Puangiangi in the middle was owned and occupied by Ross Webber and the southernmost, Tinui and its islet Takawhero, had a multitude of Maori owners but was by then uninhabited.

Victoria University took the initiative and got a grant from the South Pacific Conservation and Development Fund, which used the money obtained from the French government after they had bombed the Rainbow Warrior and killed a crewman. With finances covered it now fell to Peter and his colleagues at DOC to obtain consent for the operation. Discussions with many of the individual owners of Tinui went well– the eradication of rats being consistent with a management plan previously prepared by Tony Whitaker for the owners of the island. It was not possible to meet with every owner but a senior kaumatua of Ngati Koata deemed that there was sufficient endorsement. Ross Webber was also keen to see the end of rats on his island. He had been trapping and shooting them, without measurable effect, and he was sick and tired of them getting into his stores. A complication was that the aerial application of brodifacoum was licensed for stock-free islands only and Ross still had a good flock of romneys on Puangiangi.

By early July 1999 a 50-page Assessment of Environmental Effects had been prepared which resulted in DOC approval for the operation, the Medical Officer of Health had been notified and the Marlborough District Council had given a non-notified resource consent. The bait was ordered. In August all of Ross’ sheep were barged to a neighbouring farm on D’Urville Island. This was not without some difficulty despite the services of shepherd Lionel Roughton and his dogs: these sheep just weren’t used to being rounded up with dogs, Ross’ last one having died some time previously. As the sheep needed to stay off the island until all bait had degraded, Peter arranged with the Rai Valley butcher to get a meat pack for Ross onto the weekly mail boat.

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Ross Webber’s sheep head for D’Urville August 1999. Peter encourages lead sheep on board at the end of a sturdy rope.

After these months of preparation the actual operation, organised by Mike Aviss and DOC staff from Picton, was completed in a day – 24 August 1999. There was no non-toxic pre-feed. The bait [Pestoff 20R as 6 g pellets with a concentration of 0.02 g/kg brodifacoum] was flown from a barge moored at Tinui and applied in sixty-metre-wide swathes at 15 kg/ha. Bait was spread by hand on Takawhero to the southeast of Tinui.

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Ready to spread the brodifacoum, 24 August 1999

There is good reason to believe the eradication was successful. Trapping soon after the operation failed to detect rats on any of the islands. The juvenile tuatara were then duly moved to Wakaterepapanui, along with green gecko and giant weta.

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The helicopter finds a place to land on Wakaterepapanui; tuatara being unloaded. Photo courtesy Jo Monks.

When Puangiangi came on the market in 2012, we were not sure it had stayed free of stoats and rats, the two most likely invaders. We also didn’t know about the other islands as Wakaterepapanui is seldom visited and the bait stations on Tinui are not checked. Sue and I were really only considering Puangiangi amongst competing options for our next project because of the predator eradication, and I guess we would have walked away if our pre-purchase visit had shown they were back. Sue remarked that it really is just a useless, though beautiful, piece of rock if it can’t be kept all but free of pests.

When we landed that March, the proxy tracking tunnel on the firm golden sand at Boatshed Bay was free of little mammalian footprints and there was no sign around the buildings (rats would want for shelter more than they would want for food on a place like Puangiangi). Common gecko, which Peter remembered in only small numbers during the 1980s, were everywhere; darkling beetles and giant tree weta (at instars you just don’t see on the mainland) likewise. Our first night in the house in May was frightening though. The scratching and thumping of animals in the walls and ceiling made us think for a while that it must be riddled with rats, until we found it was a favourite gecko residence. Indeed when we opened up some walls for plumbing fittings, 200 mm of accumulated shed gecko skins and droppings were piled up on many of the dwangs. And there were no mummified rats anywhere.

In the future, stoats may occasionally swim from D’Urville, but we hope the swift currents will mean that any arrivals are single (and not pregnant). Any re-invasion of rats would likely be from boats. It was a calculated risk to install moorings on safety grounds, and we can only hope that no-one runs a line to the land when they are moored. There will never be a jetty and we will continue to wade ashore. Trespassers do beach boats and kayaks and this creates considerable risk. The No Landing signs should make it obvious what is required and locals have been asked to watch for illegal landings and to intervene as required. Dogs being let ashore from boats would also be a disaster as they would find some of the ground birds there irresistible.

After the project got under way in 2012, Peter set out a line of DOC200 traps at landing sites and in outbuildings, baited with Erayz and checked monthly. We have since extended the network to 17, with good coverage along the ridgelines and tracks which the animals would prefer to use. If we were never to do anything else on the island, keeping the traps intact and serviced would be the job that does get done.

The Telecom Hut

Just to the east of Ross Webber’s house is a little building made of lightweight metal panels, tied down with wire and with a locked door. At the rear is a telephone pole with climbing spikes, giving access to an old aerial and a solar panel from the 1980s. On our first visit to the island after purchasing it in the mortgagee sale, we brought out a locksmith who had driven over to French Pass from Nelson to meet us. He quickly gained access to the house and shed and installed new deadlocks, since beefed up with various other devices. We also encouraged him to cut a key for the little hut and I gather he got permission from the appropriate people as presumably the equipment inside was not owned by us.

Inside was a pile of grumpy geckos, several hundred metres of old cable, a deep-cycle battery and solar controller, an auxiliary telephone handset, a “Country Set” for receiving and transmitting over a microwave link to the mainland, and several old inspection forms filled out and left. On our pre-purchase visit we had been able to spot that there was a telephone in the house, by jumping up and grabbing brief looks through the salt-covered kitchen window (funny, we have never had the windows covered in salt since). I’d arranged with Telecom to get a subscription to start on Settlement Day, which was slightly complicated by the previous account having not been paid for some time. We were delighted to discover that the phone worked perfectly, if a little scratchily on the incoming side. People back on the mainland can hear very clearly however.

The Telecom hut is next to one of the kohekohe forest remnants, the only piece in the central western part of the island. We instantly dubbed the forest Telecom Bush, which also alludes to a remnant back in the Makara area of Wellington called Post Office Bush, which I have had the pleasure to visit with Wellington Botanical Society. Telecom Bush was good sheep shelter, and although no longer under pressure from the sheep, is not yet getting its understory back. It is however in the territory of one of the original robin pairs, and Peter found one of the first nests after translocation had been built in Telecom Bush.

Ross told us that he had had the telephone connected in the early 1980s, just before Telecom was privatised. For the cost of a city telephone connection, Ross got special equipment installed in one of the more remote places in New Zealand. I gather they may have given him some decommissioned lead-acid batteries and a solar panel too. (When we arrived there were two generations of solar panel on the shed roof, supplying electric light to part of the house. The 80’s-vintage one was the same as on the telephone pole but the connections had long rotted out. A more recent panel was charging the old batteries in the porch, and there was a little post-Ross electric water pump also to supply running cold water to the house. We had no idea how to maintain the system but it did limp through to the time we did a major electrical upgrade.)

Not everyone comes out on the right side of a deal with a major corporate like Telecom but I guess it was their remit to provide telephones regardless of whether an individual connection was economic for them. Imagine how useful it would have been for Ross to be able to keep up with family and friends, and to order supplies by telephone after 25 years of not having one, not to mention how much it would help if Ross were to suffer an injury or illness that needed outside intervention.

Gerard Hindmarsh wrote in one of his lovely articles about Ross that the phone was hidden in an alcove in the wall behind a calendar, lest passing yachties might sneak in an make toll calls at Ross’ expense. Ross says that story is “bloody nonsense”. There is a framed message board on the kitchen wall which might well have such an alcove behind it, but from the way the phone is installed over on the opposite wall it’s pretty obvious it has been there forever, with nothing which might have given cover from the freeloading yachting fraternity. Indeed Ross enquired whether we found useful his pencil drawing, on the wall next to the phone, of the set-up and location of buried cabling from the house through to the Telecom hut. Regrettably the drawing is most probably under a layer of lurid purple paint courtesy of the intermediate owner.

The line has non-existent bandwidth and would not support even dial-up internet, but we greatly value the security and connectivity it gives. We have since found that the island has reasonable Vodafone cell coverage, at least on the open headlands with a view to the tower at Bulwer. Telecom’s tower is a bit further away but we can sometimes text on the Telecom network from the high points. The corrugated iron roof of the house cuts the cell signal inside to zero, but we have bought a Yagi aerial and clamped it to a tall piece of pipe up behind the house, pointing it at Bulwer and occasionally trimming trees from the line of sight and making sure the aerial doesn’t spin round in the gales. My iPhone can be connected inside and so in addition to the “land” line we now also have good cell telephony and satisfactory internet (courtesy of the hot spot feature) in the warm and dry.

We were checking the equipment in the Telecom hut one day in 2013 and found a new inspection report dated that February. We had had no idea that a technician would come out regularly to check the equipment over. I was quite concerned about possible implications for biosecurity and so penned a lengthy note about the new status of the island and left it in the hut with a request to phone me. Next February I got a very friendly phone call from John the technician, who explained that he came out once a year by helicopter (when the bill is paid at least). I was able to tell him the latest of Ross, with whom he had got on well, and we established that there were no concerns about dogs, or rats hiding in equipment, as the tech serviced the public estate conservation islands as well and was well up with the special requirements for gear checking and so on.

(The tech works for a company which was spun off from either Telecom or one of the electricity companies. I lose track of all that and am tempted to refer to everyone as either The Post and Telegraph Office or the Electric Power and Gas Board, but shall use Telecom in this article and forget either their previous or subsequent incarnations.) Whilst it is hilarious that we receive a $1500-plus helicopter visit once a year to check our fifty-dollars-a-month phone line, I did say to John that he might want to coordinate with us and share a boat to the island. He explained that they used to go by boat but with the helicopter they can do eight visits a day compared with two previously.

The phone line was dead one visit in Spring 2014 and after experimentation Peter and I figured it might be a cable fault somewhere between the Telecom hut and the house. Out of natural love and affection for Telecom we thought we should have a go at fixing it rather than contact Faults and assert that the $4.95 monthly line maintenance fee might be spent on another helicopter trip. I fronted at the electrical wholesaler back in town, asked a bunch of dumb questions which were helpfully answered by the sales clerk and a customer, and returned to the island with 63 metres of the latest gel-filled cable, a new handset, connection box and the like. We hooked up the new cable in a temporary manner and from first principles were able to work out what the blinking lights on the Country Set meant, and that all the existing equipment was indeed OK apart from the old cable. At that point I realised that my pacing out of a metre needed recalibration and we were 4 metres short on new cable. Fortunately we were able to shake the geckos out of the enormous coil of spare cable in the hut- which I had clean forgotten about- and spend a hot afternoon putting it in a new trench.

This winter the phone gave trouble again and it was clear that the battery was not charging enough to work the transmitting and receiving equipment. This did mean contacting Faults and I crafted a careful email, explaining that the fault was in a remote location, was related to the solar panel and/or battery, and that there was no point sending me a standard reply inviting me to walk around the house, check all the extensions, unplug the ADSL line filters and whatever else they say to do before they will send out a technician. They duly sent me a reply inviting me to walk around the house, check all the extensions, unplug the ADSL line filters and whatever else they say to do before they will send out a technician. Fully expecting this I had copied the email to John the technician and eventually he or I was able to get the help desk to actually read my message and assign him to the job. We now have had another helicopter visit and sport a shiny new battery and a working phone once again.

I’m really happy to have and use this somewhat anachronistic piece of infrastructure. It is important to our safety and it reminds us of Ross’ time on Puangiangi and what a step forward it must have been for him to get the phone on. These days the kereru like to perch on the aerial of the Telecom hut, the guy wires moan in the wind, the geckos are largely undisturbed inside, and the old Country Set does its job.