The Cape Sanctuary has marked a biodiversity milestone following the hatching of two sooty shearwater petrel chicks.
The sanctuary has translocated three different species of petrel since 2008 – Cook's, grey-faced and the common diving petrel from offshore islands – but the new chicks are a result of breeding pairs being attracted to the site.
Nesting boxes and a sound system which plays eight types of petrel calls each night located underneath the birds' flight path successfully attracted two breeding pairs to the sanctuary's seabird enclave on the cliffs of Cape Kidnappers.
The first to arrive were the fluttering shearwater, which in 2017 started prospecting but to date have not hatched a chick.
About seven sooty, titi, began prospecting last year, two of which were successful.
Cape Sanctuary founder Liz Lowe said the new additions proved that if the right habitat was in place, breeding pairs would come.
"We monitor our burrows all year and I noticed these sooty were prospecting in the same burrows as our grey-faced petrel chicks," she said.
"They're a totally different bird and I knew it wasn't a grey-faced and noticed that when the grey-faced left they went in and used the same burrows and laid an egg."
Over the next two months, the chicks will continue to be fed by their parents, before the process of fledging begins, whereby they stop being fed, lose weight, gain adult feathers and ready themselves to launch.
The seabirds are in a "maximum-security wing" located at the top of the 2500-hectare sanctuary, where native vegetation has replaced the farmland and there is a designated runway for the chicks to spread their wings before fledging.
The second predator-proof fence allows extra protection for their taonga, including giant wētā, tuatara and takahē.
Lowe said "everything flourishes" when you have all your vermin under control.
Biodiversity Hawke's Bay general manager Debbie Monahan said work undertaken by the sanctuary is helping biodiversity flourish in the region.
"It is a good example of the difference a predator-free environment makes to biodiversity," she said.
Although the gender of the two chicks is unknown, Lowe hoped they will return in seven years, each with a breeding partner.
Hariata Dawn Bennett, of Ngāti Mihiroa, began supporting the conservation efforts in 2009 and said the latest arrival is the fruition of hard work.
"It's actually been a lovely partnership, but really when you look at it, for Māori it's basically bringing back our taonga that a lot of hapū and different iwi can't afford to do," she said.