Kea survival during aerial poisoning for rat and possum control
- Biodiversity Group, Department of Conservation, Private Bag 5, Nelson 7010, New Zealand
The kea (Nestor notabilis) is a highly intelligent and adaptable omnivorous New Zealand parrot. These traits potentially put kea at risk of poisoning during vertebrate pest poisoning operations. However, as kea fall prey to introduced pests, they also gain from pest control, creating a cost-benefit situation. Pest control in kea habitat is mainly by aerial 1080, the distribution of sodium fluoroacetate poison pellets by helicopter. Understanding the net outcome for kea of this pest control method is extremely important because kea are endangered and aerial 1080 use is controversial. We use 222 monitoring cases of individually marked kea at 19 aerial 1080 operations to model kea survival of aerial 1080 operations with respect to five variables. Proximity to human-occupied sites where kea scrounge human food was inversely related to survival; the odds of survival increased by a factor of 6.9 for remote kea compared to those that lived near scrounging sites. High survival in remote areas is explained by innate neophobia and a short field-life of prefeed baits, which together preclude acceptance of poison baits as familiar food. Elevated risk to kea living near scrounging sites is explained by learned neophilia, possibly exacerbated by lead poisoning. Survival was also related to the history of aerial 1080 treatment at a site; the odds of survival increased by a factor of 21.3 at sites with repeated operations compared with first time treatments. This effect is possibly due to selection for neophobic phenotypes. We suggest that 1080 poisoning risk management for kea should focus on reducing human food availability through an advocacy campaign. If most kea have not been fed by humans, then the long term outcome of the South Island aerial 1080 programme should be positive for the kea.