First Line of De-Fence

The first of its kind in the world, Zealandia’s fence prevents all kinds of mammalian predators from entering the 225-hectare sanctuary inside. 

The curved top hat stops climbing predators, the skirt prevents burrowing mammals, and the mesh is fine enough that most mammals can’t get through (the only exception to this is baby mice). It is also high enough so that jumping animals can’t get over. 

Possum spotted on the outside of the fence. Photo by Geoff McLay

With so much riding on this fence staying in top shape, Infrastructure ranger Gary and his team of 70(ish) fence checker volunteers play a critical role in ensuring the safety of the sanctuary.

These volunteers take turns checking sections around the perimeter of the fence and look for anything that could allow a mammal to gain access inside. Any findings are reported back to Gary.  Looking for potential issues is no small feat when even a tiny hole can compromise the fence. For example, finding a patch of rust on the fence might not look too bad initially but as Gary explains, “The problem is rust will expand 10 times the size of its original metal. By the time you've scraped all the rust off, you'll end up with a tenth of the size of the wire link, which is unacceptable.” A gap like that could mean a predator could slip in, “So, we have to put a patch on that.”

The fence is about to celebrate its 25^th anniversary later this year and the team is now looking at the fence and how we can ensure it keeps doing its important job, well into the future.

This future thinking involves a lot of planning and organising from the team. When the fence went up in 1999, no fauna species had been re-introduced yet. Now, 25 years later, the sanctuary is full of life, which adds more logistics to consider for the team as they begin to refurbish the fence.

The planning for the area of the fence which will be the first to be refurbished is currently in the works. “We've got our wonderful partners, GHD providing specialist geotech and engineering work on solutions and that section is probably 200 metres. That will be a test case for the fence [refurbishment project]. When we deal with that section there’s an opportunity to change the design, so do we change it? Do we need to change it? Do we change the materials we are using?”

We’ll also have to build a temporary fence and develop a strategy to manage predators, including deciding how and where trapping occurs before the work begins.

Being the first to carry out a project like this isn’t anything new to us at Zealandia. From the fence rehabilitation to continuing our toitoi translocation and veteranisation of the pines, this year alone we are carrying out some truly innovative and groundbreaking mahi/work, which your membership helps us to do.

Looking forward, Gary is hopeful for the future of the fence. “I can see it one day, maybe we don't actually need a fence, but for now, we still need a fence to protect that biodiversity for Wellington and New Zealand.”

This work all takes time and money so if you’re in a position to help us keep the fence in top shape, please consider donating or becoming a member. 

Hero photo: Zealandia fence. Photo by Sean Spivey.