Ten years ago, 22 pīwauwau, or rock wrens, went missing following a 1080 operation in the Southern Alps. For conservationists, it was a worry. The poison was certainly controlling rats and stoats, which had been preying on the pint-sized birds—but were the wrens taking the bait, too?
In the summer of 2019, in Kahurangi National Park, 15 pioneering pīwauwau were strapped up with radio-tag backpacks weighing half a jellybean, and given colourful identifying ankle bracelets. Mountain slopes were scattered with 1080. Department of Conservation researchers then kept tabs on the wrens for eight days. All the birds remained safe during this risky period when snacking on the bait would have killed them.
Then, nine days of heavy rain washed away the 1080. When the weather cleared, researchers couldn’t find one of the wrens—the battery in his backpack had puttered out. A second had been snaffled by a falcon, leaving behind the tag and a tattered feather-fluff. Another bird had died on her nest. Her wee body was sent to Manaaki Whenua—Landcare Research and tested for the presence of 1080. None was detected. In a recent paper, the researchers conclude that 1080 probably hadn’t infiltrated the wrens’ food chain. Those vanished wrens from 2014 had likely succumbed, instead, to an unseasonable snowstorm.