Emotions were running high outside Brook Waimarama Sanctuary in Nelson today, with concerned residents gathering outside its gates to protest a poison drop.
The Brook Valley Community group lost its legal challenge on Thursday to stop the brodifacoum drop from taking place.
Two helicopters this morning began dropping the poison intended to eradicate predators and pests in the 711-hectare reserve.
Brook Sanctuary media advisor Angela Ricker told 1 News they were delayed this morning, following the discovery of a helicopter refuel tank which had be drilled into and emptied overnight.
Three people were arrested this morning and eight people were trespassed from the area last night.
Brook Valley Community Group lawyer Sue Grey has written a letter of complaint to police about the issuing of trespass notices.
"It's extremely disappointing that they're still going ahead with this drop. There are so many illegalities about it... It's a very, very unsatisfactory process" Ms Grey said.
Brook Sanctuary Trust Chair Dr David Butler says the drop is "a key step. It's not a job we enjoy but it's a necessary step to achieve that full vision. A site that is close to people, to bring back some of our rarest wildlife".
The sanctuary is expected to reopen to the public by Christmas.