Volunteers in Golden Bay will soon be hand-feeding pakahā or fluttering shearwater chicks once 100 birds are relocated to Cape Farewell.
A teenage volunteer with the HealthPost Nature Trust, Nate Wilbourne, said the chicks would be flown from Long Island in the Marlborough Sounds to Wharariki this afternoon.
They will be hand-fed and cared for by a team of trained volunteers for up to six weeks until they fledge.
The birds will then spend up to three years at sea before returning to breed on the cliffs of Cape Farewell.
"Over at Wharariki in Farewell Spit, our vision is to create a wondrous nature sanctuary, but part of that is restoring some of the species that would have been abundant over there, such as the fluttering shearwater which is now being restricted to offshore islands," Wilbourne said.
The Wharariki Ecosanctuary was established three years ago at the base of the Spit by the online retailer HealthPost.
The trust plans to translocate 250 pakahā to the sanctuary over a three-year period to create a sustainable population.