A breeding pair of alala, or Hawaiian crows, has built a nest at the Pu‘u Maka‘ala Natural Area Reserve on Hawaii island — a sight unseen in Hawaii forests for nearly 20 years, according to state and wildlife biologists.

It is a milestone in efforts to bring back the Native Hawaiian crows, which went extinct in the wild nearly a quarter of a century ago.

In early April, team members observed two birds, Mana’olana and Manaiakalani beginning to build a “nest platform structure” near their 2017 release site. Manaiakalani, the female, has begun to sit on this nest.

“While it’s difficult to see exactly what’s in the nest from observations on the ground we do believe that Manaiakalani is likely sitting on eggs and we’ve observed her male partner, Mana’olana bringing her food regularly,” said Alison Greggor, a postdoctoral research associate with San Diego Zoo Global, in a news release. “Alala typically lay between three and five eggs and will incubate them for an average of twenty-one days. If these eggs hatch the chicks would be the first alala hatched in the wild in two decades.”

Biologists, however, remain cautiously optimistic about this latest development, saying many factors are involved in the success of this first nest. First-time parents are not usually successful, they said, and it is not uncommon for several attempts to take place before a successful fledging of chicks.

The alala have been hatched and reared in captivity at the Keauhou and Maui Bird Conservation Centers as part of The Alala Project, a partnership between the state Division of Forestry and Wildlife, San Diego Zoo Global, and the U.S. Fish and Wildlife Service.

Over the past two years, 21 birds have been released into protected forest areas on Hawaii island.

Currently, team members are monitoring the nest from afar, and discreetly, while documenting their observations of the behaviors of Manaʻolana and Manaiakalani.

“Hawaiian forests are family; there is a shared ancestry among the people, plants, animals, and landscapes,” said Rachel Kingsley, education and outreach associate for The Alala Project in a news release. “By returning the alala to the wild, we are welcoming home a family member that has been away for a long time. The fact that these birds have been able to build a nest on their own shows that these birds are comfortable in the forest they live. Our family is growing.”

Another release of captive-bred alala is scheduled for later this year.