What happened at Okarito with kea deaths brings into sharp focus the main issue with 1080. Yes, it is the best way to kill possums and other predators, but is the inevitable collateral damage to wildlife acceptable?
From a practical standpoint using aircraft to scatter 2kg of bait over a hectare with GPS navigation certainly beats walking. The problem is that baits fall anywhere in the forest and that makes it impossible to control who eats them. Unless baits either contain a poison that wildlife are resistant to, or have an added compound that repels wildlife but attracts the pests, then birds will be lost. In reality, neither alternative is foolproof.
Remember 1080 has been used over 50 years in Westland and collateral losses were just as concerning 50 years ago. I personally assessed the aftermath of the early 1970's operations in the Taramakau valley when possum number were extreme. Three weeks after the drop, the bush stank of dead possums and deer as well. Deer carcases were easy to find because they had a different rotten odour. Dead birds were also a feature though the majority were blackbirds. Initially, it was thought that too many small pieces of carrot were the cause of bird losses so the carrot cutters were redesigned. Research over subsequent years has brought many other changes including green dye, repellants, grain baits etc. But 50 years later we're still killing birds.