Of the 22 kea monitored during aerial 1080 operations in Kahurangi National Park last year, two have been killed by the poison, says Department of Conservation (DOC) Westport conservation services manager Bob Dickson.
The two kea were found dead in the Oparara Basin (western Kahurangi) following the 1080 aerial drop that occurred last November.
Mr Dickson said they were the only kea known to have died from 1080 poisoning during the entire Kahurangi operation, which took place between August and November. The other 20 were alive and accounted for after the operation.
"The kea deaths are unfortunate but without protection most kea chicks are killed by stoats.
The population gains from one good breeding season more than offset the losses of individual birds." Research showed kea had increased breeding success following a well-timed aerial pest control operation, he said.
"Kea in a forest treated with aerial 1080 in 2011 at Okarito raised four times the number of young compared to a similar forest south of Fox Glacier with no predator control." DOC was currently carrying out research into the effects aerial 1080 pest control had on populations of native species. Part of the research involved monitoring individuals of a population through 1080 operations to assess survivorship. Nests were also monitored to measure breeding success.
"Research is showing that though there can be risks for some native species from aerial 1080 pest control, the improved nesting success after the pest control can more than make up for any losses that occur. With predators reduced birds have more chance to successfully raise young to increase their populations." The Battle for our Birds pest control operations in Kahurangi National Park were timed to protect nesting native birds. Without the pest control, high numbers of rats and stoats would have decimated native wildlife, which would have had a disastrous breeding season, he said.
Without 1080, trap shy stoats and the predator booms caused by beech seed explosions would still be on the loose, he said.
Research undertaken in Kahurangi National Park between 2011 and 2014 showed whio (blue duck) populations benefited from large scale aerial 1080 pest control even while stoat trapping was in place. The aerial drop was found to provide better protection for whio nests than intensive trapping along 73 kilometres of waterway.
"Twenty-five whio are believed to have fledged in the breeding season immediately after an Animal Health Board (now TBfree NZ) aerial 1080 pest control operation, compared to none and then three in the following two years with trapping alone," Mr Dickson said.