The Brook Waimarama Sanctuary is carrying out a poison drop to kill predators before native birds are reintroduced.

The Brook Valley Community Group has failed in its last-ditch legal challenge to halt a poison drop at the Brook Waimarama Sanctuary.

The Court of Appeal on Thursday ruled against the group's bid for a stay of proceedings against the brodifacoum drop to wipe out predators and pests in the 711-hectare sanctuary.

The drop is now poised to proceed in the next favourable stretch of weather.

Environment Minister and Nelson MP Nick Smith said the appeal decision meant it was time the community group stopped its disruption to the sanctuary project.

Its opposition had become "farcical", he said.

Smith said he had spent a weekend door knocking in the Brook Valley and was amazed at the strength of support for the sanctuary.

He said the community group was not representative of the community, and its strongest support came from anti-1080 campaigners elsewhere.

Sanctuary trust board member Derek Shaw said it was time to end the court battles.

"The debate has taken place and is now over," Shaw said.

"Our intent is to conduct a safe, thoroughly planned and reviewed, and well-implemented pest removal operation that many other sanctuaries around New Zealand have done to great success.

"Let's move on and lay the ground work for a transformational ecological restoration project that will see the Nelson region teeming with native birds and rare wildlife that will inspire locals and visitors to Nelson for generations to come."

The court judgment, delivered by Justice Asher, said while the community group had raised genuine issues to be argued on appeal, other issues tipped the balance against it.

The group's failure to provide an undertaking related to damages to the Brook sanctuary trust if the group ultimately lost its main appeal against the drop was a "significant factor".

The group argued it did not have the means to make such undertaking. But the court noted some of its members were landowners and it was not satisfied that a meaningful undertaking could not be provided.

Justice Asher said evidence provided showed a year's delay in the planned winter drop would have direct costs to the sanctuary trust of $127,000, and would delay its development, and potentially damage support for the project.

The sanctuary trust was also entitled to the fruits of the High Court decision against the community group's arguments. Rejecting its bid for a stay of proceedings did not mean the group could not proceed with its appeal over laws controlling poison drops.

The community group lawyer, Sue Grey, said the decision was disappointing though the group was heartened by the recognition it had an arguable case.

She said it would be "extremely disappointing if the drop went ahead when there's so much doubt about the law."

The group has argued that national regulations allowing the brodifacoum operation were invalid and the drop contravened a section of the Resource Management Act. However, the High Court found the section cited by the group did not relate to contaminants such as brodifacoum. They were covered in another section and subsequently by regulations.