Diary of a Glenfern Fence
by Tony Bouzaid


The fence is officially opened (or shut as the case may be) but the hard slog is by no means over.

While the fence was finished early in July it is surprising how much tidying up was still left to be done. Arnie Thompson and Maurice Ngatai continued working up till 8th August spreading grass seed and laying manuka and kanuka slash onto the fence platform to prevent erosion. They also built retaining walls and backfilled where the tractor had fallen off the edge below 3 Kings on the Orama side and along the flat at Glenfern.

The Electronic Surveillance System has been installed and is operational. For the time being it is being monitored by Colin Hercus in Cambridge. The fenceline is divided into 2 sectors to enable easy detection of problems if they occur.

If anything falls on the electric wire it sets off an alarm that sends a text message to a dedicated mobile locating where the short has occurred. If a vehicle or pedestrian gate is left open a text message will advise which one it is. Likewise if the gate in the stream culvert is jammed open with debris after a storm event. The advantage of this remote surveillance system is that we will only have to do manual checks on the fence once a week as against once a day.

We have made an adjustment to the stream culvert to allow banded kokopu to be able to swim upstream. This takes the form of a rubber mat in the base of the culvert extending into the pool downstream. It provides a rough surface for the kokopu to climb.

Official OpeningAn Open Day was held on November 1st to celebrate the completion of the fence and show a film “Fencing the Kotuku Peninsula Sanctuary”. The film was professionally compiled and covers all stages of fence construction and incorporates the aerial bait drop on Kaikoura. About 50 people attended the event at the Port FitzRoy Boat Club. After a light lunch everyone walked down to the vehicle gate in the fence for a further explanation of the system and were then taken on a guided walk through Glenfern Sanctuary.

Planning is now under way for the next stage of the project which is the eradication of animal pests (rodents, rabbits and feral cats). To date half of the $200,000 required has been granted by Lotteries Environment and Heritage Fund.

Eradication planning requires considerable preparation and builds on the experience learned from other multi-species eradication projects behind pest-proof fences including Maungatautari Ecological Island (Waikato) and the Rotokare Sanctuary in Taranaki. It will take around 6 months to complete the planning documents which include an Eradication Operation Plan (EOP), Biosecurity Plan and Resource Consent applications. An Eradication Advisory Team led by Jo Ritchie from Natural Logic Environmental Management will provide specialist advice for the project.

Because eradication involves getting rid of every animal pest (as opposed to control where animals are managed to low numbers) we have had to take into account all factors which may influence the success of the operation.

One example is the areas of rank kikuyu grass outside the paddock areas. Experience from other similar projects (e.g. Tawharanui) is that long rank grass may prevent bait from getting down into some mouse habitat. So we need to cut back, spray or get our kikuyu eaten down to remove hiding spaces for rodents.

A key component of the project is having a system in place to locate any pests which may survive the aerial baiting operation. Envirokiwi have just completed cutting tracking tunnel tracks throughout the peninsula to enlarge the grid of bait station lines to 50m x 50m spacing. Approximately 1100 tracking tunnels will then be installed on this grid. They will act as the primary measure to detect surviving rodents.

After the aerial drops have been completed in winter 2009, these tunnels will be monitored every 3 weeks (for at least 6 months) until no survivors are located. If none are found after 6 months the monitoring will be reduced to once every one to three months for 2 years. The monitoring programme will require 10 volunteers for 6 day stints to complete each run.

Cat and rabbit survivors are not as easily monitored with tracking tunnels (as they are generally too big to fit inside!) and will instead be monitored through a combination of field sign and strategically placed traps. Specially trained pest detection dogs will also be used for all 3 species. A rabbit density survey will be undertaken this summer to provide baseline population data to measure the success of the eradication against.

Because the fence has open ends to the sea it is important to have a system in place that both detects and catches pests that may try to get around the fence ends. Ideally we want to catch the pests before they get to the ends. This is called ‘Buffer Control’. Bait stations and traps still have to be located in the buffer zones outside the fence ends and along the Port FitzRoy and Karaka Bay foreshore.

The coastline of the sanctuary also has a number of locations where boats moor and/or where people come ashore. An education programme which includes signage at key locations will let people know about the sanctuary and what they can do to help, e.g. check gear for signs of rodents, not run mooring lines ashore etc.

The Glenfern Sanctuary Supporters Club now has 184 GBI members. If you would like to know more about the project or are interested in joining Glenfern Sanctuary Supporters Club or volunteering please contact Tony Bouzaid at tony@glenfern.org.nz or 09 4290091.