Taranaki Mounga Project undertook aerial 1080 predator control over 31,000 ha in Egmont National Park to reduce predator numbers and give threatened species such as whio and kiwi a chance to successfully breed and raise their young. This operation is part of a much larger multi-tool approach to predator control, which will one day allow the return of lost birds such as kākā and kōkako to the mounga.
Taranaki Mounga Project Manager Sean Zieltjes says rats and possums were monitored before and after the operation using tracking tunnels and wax chew cards.
“Our monitoring showed that rat numbers dropped from 93% to 3% and possums were reduced from 61% to 10%. Ferrets and stoats will have also been killed as they ate rat and possum carcasses.
“This is a good result and will give our native species some breathing space to breed and raise their young during this next season.
“Returning species such as kākā and giving our native birds, lizards and plants the best opportunity to thrive is important, not only for Taranaki, Pouakai and Kaitake, but also the people who visit and enjoy the national park,” says Zieltjes.
DOC Operations Director Brigitte Meier says whio were monitored through the predator control operation after birds were discovered to have eaten 1080 cereal pellets in the last operation in 2016.
“Unfortunately, one of 20 whio we were monitoring died from 1080 poisoning, while a second bird died from unknown causes. A third bird was killed by a stoat or ferret prior to the operation.”
“While it’s sad to lose individual birds, we know predator control has resulted in the whio population increasing four-fold since 2010 with an estimated 200 birds now in the national park. This very successful population increase would not have been possible without interventions such as pest control.
“DOC has monitored more than 70 whio through 1080 operations in other parts of the country and none have died from 1080 before. We will be investigating why whio at Taranaki appear to be more at risk,” says Meier.
Whio forage for live aquatic insects. Poor food supply due to flooding in streams on Taranaki Mounga may have contributed to the birds eating the cereal pellets.
Research shows that aerial 1080 predator control strongly benefits whio by improving nesting success and survival of young ducklings through to adulthood.
After the previous predator control operation in Egmont National Park in 2016 the number of whio ducklings that reached fledgling stage rose from 23 in the summer of 2015-2016 to 58 in the 2017-2018 breeding season.
Whio/blue duck are a threatened taonga species with an estimated population of under 3000. They nest on riverbanks and are vulnerable to attack by rats and stoats.
The final predator control operation was completed in the Kaitake Range last week. Results from this will be monitored over coming weeks. There are no whio in the area.
Taranaki Mounga Project is ten-year landscape scale project involving the Next Foundation, DOC, iwi and the Taranaki community, aimed at removing pests and bringing back lost native species in Egmont National Park.
There have been four previous aerial 1080 predator control operations in Egmont National Park: in 2016, 2009/2010, 2002 and 1993/1994. After each operation there was a large reduction in predators, protecting threatened plants and animals.