As part of its Battle for our Birds operations, the Department of Conservation (DOC) is in a race to extend a huge trapping network in the Murchison Mountains in time to combat the predicted stoat plague over Christmas.
At over 50,000 hectares, it is already the country’s largest stoat trapping programme. It covers the Murchison Mountains Special Takahē Area, in Fiordland, in its entirety—home to the last wild population of critically endangered takahē.
“Even without the extension, checking and maintaining the existing network is a mammoth task and demonstration of the dedication of DOC’s rangers, our partners and contractors,” says Conservation Services Manager Lindsay Wilson.
This year, high levels of seed production (mast) in our beech forests is triggering a rodent and stoat explosion. Research shows that juvenile stoats leave the den looking for prey around December putting many native species at risk of predation. This also ties in with the time that many of our birds have vulnerable chicks.
In addition to the 4300 traps that are already in place, DOC has now cut a further 50 km of new tracks on the eastern side of the Murchison Mountains upon which to set another 1032 traps.
“Maintaining the huge trap network, which is spread over 300 km of track up to altitudes of 1500 metres, is gruelling, time-consuming work. It is the best option we’ve got for protecting the area’s wild takahē,” says Lindsay Wilson.
“Even with this many traps over this much land, there is still a good chance it won’t be enough in the battle against stoats this mast year—that is why we have to get these new traps in before Christmas.”
Stoat trapping has been carried out in the Murchison Mountains since 2002, primarily for the protection of takahē. In 2007 a stoat plague, triggered by a beech mast, reduced the takahē population in the Murchison Mountains from 150 to just 94 individual birds. After this event, with support from Mitre 10 Takahē Rescue, the trapping programme was expanded from 15,000ha to 50,000 ha.
“We know from experience just how devastating a stoat/rat plague can be for these birds. We want to ensure we’ve taken every step we can to prevent this from happening again,” says Lindsay Wilson.
“Because we’re dealing with such a critically endangered bird and because takahē raised in the breeding facility at Burwood are accustomed to eating cerial pellets, using aerial poison bait drops is not currently an option. Given the benefits of aerial predator control in that it provides protection for the entire ecosystem and is vastly more resource efficient than trapping, we are conducting trials into the possibility of having this tool available to us in future.”
Although the 2007 expansion of the trapping network involved placing trap lines in all of the major valley systems in the Murchison Mountains, the current trap network still has gaps in coverage.
“Once installed, these new traps will fill in most of the large gaps in the existing network and provide significantly improved ongoing protection for takahē and other stoat-vulnerable threatened species such as Fiordland tokoeka/kiwi, kea, rock wrens and whio,” says Lindsay Wilson.
“The 2014 beech seeding and subsequent rodent/stoat explosion make this an urgent priority.”