The three takahē that died were among 18 monitored by DOC’s Takahē Recovery Team after the predator control operation on 16 and 17 August. The 15 other birds are alive and further monitoring is taking place.
Takahē Recovery Programme Operations Manager, Deidre Vercoe says what is learned from the takahē deaths will inform the future management of the species.
“The three takahē deaths are upsetting. We know that the aerial 1080 predator control will have helped protect other threatened species in the area from predation.
“The takahē deaths shows how tough and challenging conservation work for native species recovery can be.
“Ultimately, large-scale predator control is essential for restoring takahē to large wild sites, without it they’ll be limited to sanctuary sites for the foreseeable future. Our shared vision with Ngāi Tahu is to return this taonga to its natural landscapes, so what we learn from this operation will be vital for informing the recovery of the species.
“One of the main reasons for choosing Kahurangi’s Gouland Downs to establish a second wild takahē population was the relatively low predator numbers which is primarily due to ongoing pest control.”
DOC carried out aerial 1080 predator control over about 50,000 hectares in the Aorere and Gouland Downs area of the park as part of its Tiakina Ngā Manu programme to help protect threatened native species including kea, kākā, whio and great spotted kiwi from rats and stoats. It followed last year’s heavy beech seed fall that caused predator numbers to rise.
Post-mortem results on the takahē first found dead show 1080 was the likely cause of death. Toxicology testing results are awaited before it can be confirmed.
Post-mortem and toxicology testing is still to be carried out to determine the causes of the deaths of the other two takahē although 1080 poisoning is a possibility.
Prior to the 1080 predator control work, three other Kahurangi takahē were lost to suspected predation since March, demonstrating the need for effective predator control. Another five died from other natural causes.
Takahē hadn’t been exposed to 1080 before, so their susceptibility to it was unknown. Research had been undertaken to find ways to reduce risk to the takahē. This included trials with wild takahē and non-toxic baits which suggested that the risk of wild birds at Gouland Downs eating baits was low.
To further reduce the risk, a 587-hectare exclusion zone where no 1080 baits were applied was put in place to cover most of the takahē population. The exclusion zone was kept as small as possible to provide predator control protection for other threatened native wildlife.
The loss of the Kahurangi birds will not impact on the continued recovery of the species. The total takahē population has almost doubled in the past seven years to around 450 individuals and is expected to continue growing at 10% per year.
The Fiordland Murchison Mountains’ population loses an average of 15% of adults from predation when stoat numbers surge following beech and tussock seeding, even with an extensive trapping network. Chick and juvenile deaths from predation are thought to be even higher.
DOC with Ngāi Tahu, our Treaty Partner in takahē recovery, will now assess what can be learned from the takahē deaths In particular, what it means for selection of future sites for wild takahē populations.
Takahē were released into the Gouland Downs area of Kahurangi National Park in 2018 to set up a second new wild population outside of the takahē’s Murchison Mountains homeland.
The overall takahē population is around 450. It includes more than 70 juveniles from last year’s breeding season. With the takahe population growing, the species moved two places along the threat classification system in 2017, from nationally critical to nationally vulnerable.
About two-thirds of the overall takahē population is spread across 16 predator-free islands and wildlife sanctuaries. Sanctuaries provide an important role in takahē recovery in ensuring survival of the species, should disaster hit the wild populations, and as breeding sites.