Conditioned aversion in kea to cereal bait: a captive study using anthraquinone.
The kea (Nestor notabilis, plural kea), an alpine parrot endemic to New Zealand's South Island, is endangered by introduced mammalian predators. Aerially deployed 1080 (sodium fluoroacetate) toxin in cereal baits is an important tool in the control of mammalian pest species in New Zealand. Kea are omnivorous and forage on the ground, and thus are at direct risk of consuming toxic baits. This study examined the degree to which kea can develop an aversion to bait that mimicked the visual, textural, and olfactory nature of 1080 baits in two standard cereal bait types, Wanganui #7 and RS5. Treatment baits contained 2.7% by weight anthraquinone (CAS 84-65-1), a secondary bird repellent that causes an emetic response through mild gut irritation. A sample of 11 captive kea were hand-offered Wanganui #7 baits, starting with untreated bait to obtain a baseline measure of consumption. Two days later the birds were hand-offered treated (repellent) baits in two sessions over four days. In subsequent sessions untreated baits were again offered to measure aversion. Of the 10 birds that consumed untreated bait during the initial session, all 10 consumed at least some treated bait and only one consumed untreated bait in the final session. The process was repeated with RS5 bait. Of the 9 kea that ate the treated RS5 bait, 4 subsequently consumed untreated bait but only one to a level that would have been fatal (LD50) with toxic bait. These results show that kea can learn to become averse to baits mimicking those used in aerial 1080 operations, and that this aversion response lasts at least through 6 interactions with baits (3 per day). This opens up the possibility of creating a learned aversion in wild kea populations, and mitigating their risk from aerial 1080 operations.