Zealandia Weasel Capture
Last updated: 12 June
Our solid biosecurity systems have been put to the test with five weasels found dead in traps at the southern end of the sanctuary over the last few days. Thanks to the sanctuary’s robust biosecurity protocols and action by the Conservation & Restoration team, the existing safeguards are working as intended.
On Saturday afternoon (7 June), a vigilant member of the public alerted the Zealandia team to a freshly dead weasel in a DOC200 trap. Duty operations rangers quickly responded, clearing and resetting the trap before conducting a wider check of the sanctuary’s trapping network. Additional dead weasels have been discovered on daily trap checks since Saturday.
These traps had been set live as part of an enhanced biosecurity response following storm-related damage to the sanctuary fence in early May.
“We have a complex and layered biosecurity system in place, including motion-activated cameras, tracking tunnels, detection dogs, and a comprehensive trapping network,” said Jo Ledington, General Manager Conservation and Restoration.
She continues, “This is exactly what our conservation team is trained for. We’re prepared for events like this, and our systems are doing their job. We will be continuing with our response until we are confident there are no further weasels in the sanctuary.”
“We don't know exactly how these weasels entered the valley but as they have not shown up on any of the detection devices deployed for the fence damage, the bodies were fresh and the traps had recently been checked and rebaited, we don't think they have been inside the fence for long.”
Introduced predators such as weasels pose a serious risk to Aotearoa New Zealand's native wildlife, which evolved without them and aren’t equipped to defend themselves. Fortunately, there are no signs of predation, and no evidence that other introduced mammals remain within the sanctuary.
This incursion is another reminder of the importance of fenced sanctuaries that provide a safe haven for our country’s taonga species until Predator Free 2050 goals are realised.
You can support Zealandia’s ongoing efforts to keep the valley predator-free by contributing to the fence appeal.
FAQs
What has happened?
A weasel was found dead in a trap set within the Zealandia sanctuary on Saturday 7 June. The trap was quickly cleared and reset by a staff member and another weasel was found in the same trap on Sunday 8 June. A third weasel was discovered in another trap on Monday 9 June. A fourth was discovered Tuesday 10 June and a fifth on Thursday 12 June.
These were DOC200 traps that had been set as part of our standard incursion response from the tree fall onto the fence in May.
How many weasels have been caught?
To date, five weasels have been caught in traps. All were freshly deceased.
Why is that a problem?
Weasels were introduced to New Zealand. Our native species aren’t well adapted to live with these very impressive predators. The Zealandia fence is very effective at keeping species like weasels out, but occasionally they get in and we need to respond.
Has this happened before?
Yes. We found a dead weasel in a trap in August 2024, and in October 2023. There was also an incursion in 2019. We have some traps that are always set as part of our standard biosecurity measures to help deal with any incursions. We have quite a complex system in place to detect intruders.
How did the weasels get in? Where was the likely point of entry?
We aren’t 100% sure, but they may have come in during the storms in early May where a tree fell on our fence. According to island incursion research, new animals will lie low and stay in a very small area for a period before exploring further afield. It may be these animals came in on the tree and have been lying low until the recent drop in temperature/wet weather or are now feeling comfortable to move about.
Alternatively, there may be another entry point they have accessed very recently – weasels can get through a tiny hole the diameter of your thumb. Our staff and volunteers have been carefully re-checking the fence and around it for possible entry sites to make sure there are no further risks.
Are there likely to be more weasels?
We will continue with our response until we are confident there are no further weasels in the sanctuary. This includes re-checking the fence to make sure it’s secure, fresh baiting traps and reviewing the footage from trail cameras used to spot any animals moving around the sanctuary. We have a mustelid dog booked to come through the sanctuary to do a search as part of our standard biosecurity measures. Mustelid dogs are another useful tool to hopefully confirm we are weasel-free.
Are the wildlife in the sanctuary in danger?
Weasels are good predators, but they aren’t nearly as voracious as stoats and ferrets. Weasels like mice, and there is a good chance this was the animals’ main source of food while in the sanctuary. However, our native species aren’t well adapted to live with introduced mammalian predators such as weasels, so we are keeping a watchful eye and continuing with our response until we are confident that there are no further weasels in the sanctuary. We aim to deal with situations like this as fast as possible.
What is happening now?
First, we re-checked the fence to make sure it is secure. We rebaited set traps to ensure the bait was fresh and attractive and are regularly checking them. We will continue to deploy trail cameras to spot any animals moving around the sanctuary. We have a mustelid dog booked to come through the sanctuary to do a search as part of our standard biosecurity measures. Mustelid dogs are another useful tool to hopefully confirm we are weasel-free. We will continue with our response until we are confident there are no further weasels in the sanctuary.
How can people help?
Responding to events like this is expensive and can take months to be 100% sure the sanctuary is safe. Right now, we could do with your support through becoming a member or donating to our fence refurbishment project:
Photo by Jerzy Strzelecki via Predator Free NZ
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