Pestproofing a Peninsularby Tony Bouzaid and David Speir

Environmental News Issue 14 Autumn 2008

Mainland islands are proving highly effective at creating predator -free habitats for endangered species. The irony of this, the first created on the Barrier (itself an island) is not lost on Tony Bouzaid. However his vision for Glenfern Sanctuary was both politically and financially achievable, and he has wasted no time in pioneering a conservation first for Great Barrier Island.

What looked so simple on paper (despite the cost); and deceptively achievable from aerial photographs proved to be a challenge that demanded everything from Tony Bouzaid and his team. Only time, the weather and the remote location would reveal the true scale of this project, and logistics of an entirely new dimension.

The concept of pest-proofing the Kotuku Peninsula was first explored in 2003, but Tony reached the conclusion then that the terrain made it impracticable. During the next few years pest-proof fences really came of age with a number of sites appearing around the country.

A visit in 2005 to the nearest one at Tawharanui near Warkworth for a Sanctuaries of NZ Conference provided Tony a good opportunity to see a finished fence in situ and examine how the open ends on the shore were dealt with. However the terrain was mild in comparison to the Kotuku Peninsula where the elevation reaches 200m, only 1200m from Karaka Bay in Port Abercrombie and 850m from Port FitzRoy.

The chart shows the boundaries of the fenced area of
Kotuku Peninsular as well as adjacent Kaikoura Island
which will be pest eradicated shortly.

At the newly established Karori Wildlife Sanctuary in Wellington the building of an almost vertical section of fence proved what could be achieved over very difficult terrain. Then came the completion of the 47km fence around the mountain at Maungatautari, which included some very steep sections up the side of the mountain. This seemed to indicate the 2km Glenfern Sanctuary fence would be a breeze.

In February the decision was made to proceed with building a pest-proof fence across the Kotuku Peninsula in 2008 if sufficient funds could be raised. Jo Ritchie was employed to prepare a feasibility study, an ecological assessment, help with consultation and prepare resource consent applications. Her experience in facilitating the Tawharanui pest fence made her well qualified for the job.

Orama had already given approval to build the fence across their land. Letters of support were obtained from all adjacent landowners’ including the Department of Conservation and an application was made to Ngati Rehua, the Great Barrier hapu, for support.

In March 2007 fund-raising started in earnest. With seed funding by the Bouzaid Family Trust of $215,000, applications were lodged with the ASB Community Trust, the Biodiversity Condition Fund and Lotteries. With help from Joel Bouzaid and Scott Sambar from OPC (Outdoor Pursuits Centre) a PowerPoint presentation was compiled to promote the project and hopefully find sponsors. Several dinner presentations were given with the whole of the North Barrier community invited, which generated good attendance. The PowerPoint was also presented to the Orama Trust Board, the Motu Kaikoura Trust and the Sanctuaries of NZ Conference in Silverstream.
Ngati Rehua examined the route of the fence and gave unequivocal approval that endorsed the project as a major contribution to endangered wildlife. and enabled an agreement to be negotiated with the Department of Conservation for the use of a stretch of 100m of reserve land.

Members of the contracted team Xcluder Pest Proof Fencing Ltd made several trips to Great Barrier Island to ascertain the feasibility and confirm the route of the fence. From this investigation it was realised that 68 pine trees on the Orama side had to be removed in advance. The fence requires 4m clearance outside (for jumping cats); and 2m inside, to remove the danger of trees or branches falling and damaging it.

In October approval was received from the ASB Community Trust for $58,800 and the Biodiversity Condition Fund for $120,000 over 2 years. By the end of the year private donations totalled a further $11,000.The Glenfern Sanctuary guided walks and sales of T shirts and accessories contributed a further $8,000.

In late 2007 an added impetus to the building of the fence was the loss of two female robins to rats and another to a cat. This left an already depleted robin population with 4 males and 1 female. Surveyed damage to seedlings and undergrowth by pigs (and the resultant susceptibility to erosion) reinforced Tony’s intent.

With the majority of the money in hand or promised, and with approval and commendation forthcoming from Ngati Rehu and DOC it was decided to proceed.
Resource Consents were applied for in January 2008 but due to a backlog at Auckland City the consents were postponed to March 31st. With a deadline of April 30th for completion of the earthworks work had to begin by March 31st. A Heads of Agreement with Orama was negotiated.
Con Flinn was engaged to remove the pine trees, some of which were nearing the end of their life-span and were up to 1.8m in diameter. Over the course of four weeks he felled over 60 pine trees on to what would become the fence platform, so the branches could be trimmed ready for chipping.

With ARC consents already in hand, land use consent conditions agreed and assurances from Auckland City, the barge charter for shipment of machinery and materials was booked for the 29th March. This was the last opportunity to land at Karaka Bay on a reasonable tide in the middle of the day or face a delay another two weeks.

The barge sailed on the 28th evening to Port Abercrombie awaiting the tide on the 29th. Over a span of four hours the Orama truck, the FitzRoy House Unimog, two diggers and the barge forklift unloaded all the equipment and materials. A start was then made on the access to the top of the hill from the main Orama complex. The following day (with the access largely completed) the assembly area was cleared of pine logs and debris to enable the materials to be shifted up the hill.

Monday was a pre-construction meeting with representatives of the consent authorities, the environmental consultant, the contractors and the land owners who then walked the line of the fence to Port FitzRoy. Work began immediately after with forming the fence plat-form down to Arthur’s Bay and up the Telecom line.

The earthworks contractors were well on their way up the Telecom line by the time the fencing team arrived the same day, who immediately started drilling strainer holes and ramming posts. Once the strainers were secured the tensioning wires were attached and tensioned ready for installing the capping channel and battens.

During the week all the materials required for the Port FitzRoy end of the fence were trucked round to Glenfern. The pad for the vehicle gate on the top of the Orama hill was prepared and cut-outs and sumps for runoff and sediment control were dug. The fence platform was continued with installation of culverts below the volcanic outcrop known as Three Kings (where OPC take their students for abseiling) as well as over on the Orama side.

The following week the platform was formed down the FitzRoy hill to just above the stream, and the fence erection began in earnest with battens and capping channel installed up the hill from Arthur’s Bay (Orama). On the FitzRoy side wet ground allowed only work to the platform through to the FitzRoy House front gate. Erection of the fence continued up the Telecom hill but rain again stopped work until the 1st May.

The prospect of fine weather saw a team of seven arrive from Xcluder on the 6th. Solid progress was made with the team working from dawn to dark installing mesh and capping on the Orama section.

On the 9th and 10th it rained again with some heavy downpours but the team managed to get the posts bored and rammed at the bottom of the FitzRoy hill and sediment control fences installed above the stream culvert and below the cut-off bunds.

Fine weather returned again on the 11th , drying the ground and with 7 men working, steady progress was made. The first few days saw the remaining post-holes bored below Three Kings and the finishing of the remaining sections above and below the Orama stock gate. By mid-week the ground was dry enough to work up the Telecom line to the top of the FitzRoy hill. Because of the steep south-facing slope and the high trees adjacent it was not dry enough to work down the FitzRoy side till the end of the week.

Even then the steepness of the slope combined with a greasy clay surface made for interesting maneuvers. The  and the post-ramming tractor were connected by wire hawser across the top of the hill. So counterweighted, the tractor was lowered down the hill. The Unimog had to be driven down the other side to pull the tractor up again. After a while it became necessary to use the combined weight and traction of the Orama tractor and the Unimog to get the ramming tractor back up the last steep section. Skillful teamwork allowed the posts to be positioned successfully on the steepest section without incident.

Meanwhile the last fence section to the shoreline at Arthur’s Bay was completed and the concrete pad for the pedestrian gate laid. With rain forecast for the 19th or 20th the team worked right through the weekend to get the remaining posts down the FitzRoy hill bored and rammed.

It rained briefly Sunday night just enough to make it too slippery to use the ramming tractor or the Unimog. Rain began in earnest Monday morning but didn’t last long so the tractor was able to ram the last few posts at the top of the Telecom line. This section was then meshed up during the week. With the Telecom line too slippery to extract the Unimog or the tractor, work began on finishing the fence along the flat to the front gate at FitzRoy.

The last culvert was installed beside the FitzRoy gate and geotextile laid over the mud from the drive most of the way to the next culvert. Metal was laid over the top by the FitzRoy farm tractor to make the track to the stream culvert accessible. The team continued to work until washed out by rain on Friday afternoon.