The U.S. Fish and Wildlife Service today released a revised recovery plan for the endangered Hawaiian crow, one of the rarest forest birds in the world.

The new plan hopes to prevent extinction of the bird, known as the alala, and to restore populations to allow removal of the species from the endangered list.

It includes expanding captive propagation, establishing new populations in managed habitat, protecting suitable habitat, managing threats to the species, increasing public support and continuing research and adaptive management practices.

The Fish and Wildlife Service estimates the plan will cost more than $14 million over the next five years, mostly because of the high cost of broad habitat restoration needs.

The birds, which have only been found on the Big Island, haven't been seen in the wild since 2002. Currently, 56 alala are being cared for at two bird conservation centers on Maui and the Big Island that are managed by the Zoological Society of San Diego.

According to population genetic modeling, the population needs to grow to at least 75 to avoid further loss of genetic diversity and to begin reintroduction to the wild.

Alala are revered by Native Hawaiians. Its feathers were once used in kahili, a symbol of royalty. The alala are the second largest forest bird in Hawaii after the endangered io, or Hawaiian hawk, and is the only surviving member of a group of crow species that once inhabited the Hawaiian archipelago before human colonization.

Abundant in the 1890s, the population declined sharply despite legal protections dating to the Territory of Hawaii in 1931. By 1987, the alala was reduced to a single bird in north Kona and fewer than 20 in central Kona.

More than two dozen alala that were raised in captivity were released between 1993 and 1998. However, 21 died and the remaining six were recaptured and placed with the captive flock. The last known reproduction in the wild was in 1996.

Threats to the crow include being killed by nonnative mammals, losing their habitat, and suffering disease and fragmentation of the population. Inbreeding may also be reducing the reproductive success of the captive population. And loss of wild behaviors in captivity may reduce the survival skills of reintroduced birds, the service said.