A Hawaiian petrel fledged, flew out to sea for several years and recently returned to its birthplace on Kauai.

Seabird conservationists are celebrating this as a significant milestone following years of painstaking efforts to establish a safe, new home for the endangered Hawaiian petrels at Kilauea Point National Wildlife Refuge on Kauai’s North Shore.

The bird is the first one known to have returned among 87 chicks that were translocated from remote Kauai mountains to the fenced-in habitat at the refuge called Nihoku four to five years ago. Researchers see this as an early sign that chicks that fledged between 2015 and 2019 imprinted on the site and will return to breed.

Seabirds have “high site fidelity,” according to researchers, and most return as adults to breed where they hatched. Burrow-nesting seabirds, such as petrels and shearwaters, often imprint on a site when they see the night sky for the first time.

Researchers spotted the petrel early this month via trail camera footage that is checked periodically. The image of the petrel was captured May 30, and it appears to have a leg band.

“After so many years of hard work in the mountains and at Nihoku by everyone in this project, it is hard to put into words exactly how exhilarating it is to see this special bird appear on camera at the site,” Andre Raine, Kauai Endangered Seabird Recovery Project leader, said in a news release, adding he jumped out of his seat when he first saw the image. “Considering all of the threats this species faces on Kauai, their future on the island will only be assured if we use every conservation tool in our arsenal, including creative techniques like the translocation and social attraction project at Nihoku.”

The Nihoku Ecosystem Restoration Project, created in 2012, is a multipartner effort involving numerous nonprofits and agencies, including the Kauai Endangered Seabird Recovery Project, a state project administered by the Pacific Cooperative Studies Unit; Pacific Rim Conservation; Kilauea Point National Wildlife Refuge, U.S. Fish and Wildlife Service; and the American Bird Conservancy.

The project’s goal is to protect rare coastal ecosystems and provide a predator- free nesting area for native seabirds including Hawaiian petrels, also known as uau, and Newell’s shearwaters, known as ao.

The Hawaiian petrel, or Pterodroma sandwichensis, makes an “oo-ah-oo” call after sunset and nests in burrows or rock crevices of remote mountains, where it is vulnerable to non-native predators such as rats and cats. They are also threatened by collisions with power lines and by artificial lights, which disorient them and cause them to drop to the ground, where they can be hit by cars or ravaged by predators.

Raine monitors seven nesting areas in Kauai’s mountains and has seen major population declines — 78% for the Hawaiian petrel and 94% for the Newell’s shearwater — between 1993 and 2013.

For five years, the project team has flown by helicopter to rugged terrain, hiking across slopes to find and monitor the burrows of both species, then transported chicks to Nihoku just before they were about to become imprinted.

Pacific Rim Conservation’s animal care team then fed and monitored the translocated chicks until they fledged. Since 2015, the team has successfully fledged 87 petrels and 67 shearwaters from Nihoku.

The project partners now hope more petrels will start returning to breed at Nihoku, with the ultimate goal of establishing a thriving, new colony safe from predators, according to American Bird Conservancy seabird program director Hannah Nevins.

To make Nihoku more attractive to the birds, they built about 50 artificial nest boxes and are playing the species’ calls over a sound system.

“If even half of the birds come back, that’s a few breeding pairs,” Nevins said.

Conservationists have also protected mountain nest sites, but establishing the safe haven at Nihoku is a long-term strategy and insurance for the population, she said. The ultimate sign and proof of the project’s success will be the presence of breeding pairs at the site — a milestone they are eagerly awaiting.