The Department of Conservation (DoC) says it is devastated at the disappearance of several endangered eggs and chicks from New Zealand's rarest breeding bird, the fairy tern.
In the latest incident, an egg and a dummy egg vanished from a nest in the Mangawhai Wildlife Refuge, near Auckland.
Several days earlier, two eggs and two chicks disappeared from nests at Waipu.
The fairy tern is on the edge of extinction, with fewer than 40 birds left.
DoC's community relations manager, Abby Meagher, says there is strenous predator control at the Mangawhai nest, and it is possible the disappearance is the result of human activity.
She says new surveillance cameras will be established at the sites.
Listen to Abby Meagher