Two of 13 kea monitored by ZIP as part of the trial are suspected to have died from 1080 poisoning last week. The remaining 11 birds are alive. The dead adult female kea have been sent to Wildbase at Massey University for testing to determine the cause of death.
The ZIP research and development trial aims to completely remove possums and potentially rats, and significantly reduce stoats, from the 12,000-ha research area, and to prevent predators from re-establishing. In addition to the use of aerial 1080, the trial also involves the establishment of a network of devices to detect any survivors or invaders, and the use of ‘spot treatments’ to remove them.
DOC West Coast Operations Director Mark Davies says when the decision was made to give ZIP permission to carry out the aerial 1080 component of the trial, the Department was fully aware of the increased potential risk to kea.
“Losing two out of 13 monitored kea is in the order of what was expected as an elevated risk to kea from the increased number of prefeed applications and the more intensive use of 1080 in the ZIP trial.
“We accepted the increased risk because this is an important research trial that could lead to a breakthrough in New Zealand becoming predator free at a landscape scale.
“In addition, the methods ZIP used to mitigate the risk to kea were very promising in early trials and deserved further testing.”
“It’s too early to say how effective the bird repellent aversion training and distraction with tahr carcasses has been, but this will be part of the trial results,” says Mark Davies.
“The knowledge gained by this work will ultimately lead to a better and more secure future for kea and other threatened native species.
“It’s always unfortunate to lose individual kea but our research shows that this level of loss will be offset by significant increases to the kea population from improved nesting success and survival of young birds without predators.”
There is a healthy kea population in the vicinity of the Perth River valley, which is due in part to a long history of predator control in this area, including multiple 1080 predator control operations, says Mark Davies.
“We are committed to the ongoing protection of this kea population from predators and will maintain the intensive stoat trapping network installed by ZIP at this site once their programme is complete.”
The method of applying 1080 developed by ZIP to remove predators differs from standard DOC predator control methods with two pre-feeds of non-toxic bait before the application of toxin, which is applied first at double the standard rate, followed by a second treatment a month to six weeks later, applied at the standard rate.
Kea aversion training with repellent-laced non-toxic baits placed next to tahr carcasses and then distributed more widely, took place prior to 1080 treatment. The repellent baits (using anthraquinone) make kea feel sick and potentially train them to avoid the later sowed toxic baits.
The kea population in the Perth River valley is in relatively high numbers with a good mix of juvenile and adult birds. There’s strong evidence that the natural barriers provided by the valley’s big rivers and the Southern Alps/ Kā Tiritiri o te Moana, in combination with DOC’s previous aerial 1080 operations in the area, have benefited kea and other native species in this area.