The U.S. Fish and Wildlife Service has launched a major effort to save the critically endangered Hawaiian crow, one of the rarest forest birds in the world.

The new plan, updated for the first time since 1982, aims to restore and protect populations of the 'alala and prevent its extinction.

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 $14.3 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. The 'alala is the first of Hawai'i's forest birds to be saved from extinction by captive breeding.

"The fact that the species is extinct in the wild means that its former habitat is no longer able to support the population for whatever reason," said biologist Jeff Burgett, who is charged with the recovery for the Fish and Wildlife Service. "Unless we change it in ways that are better for the bird, it has no suitable habitat."

Their habitat has been affected by the introduction of non-native predators and threats such as feral cats, pigs, mongoose and cattle, which can destroy the vegetation of the forest and spread disease.

"We've let mongoose and cats and rats and all these things out there. They're taking Hawai'i away from us, slowly but surely," Burgett said. "If you want to keep Hawai'i, then you've got to do something to control those things."

Sixty 'alala are being cared for and bred at two bird conservation centers on Maui and the Big Island that are managed by the Zoological Society of San Diego. According to 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.

"The point is not to keep them in a box," Burgett said. "The point is to build the flock up to the point where they're generating enough young that you can put them back out in the wild."

Revered by Native Hawaiians, the 'alala is the second-largest forest bird in Hawai'i 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 back to 1931. By 1987, the 'alala was reduced to a single bird in north Kona and fewer than 20 in central Kona.

With brownish-black feathers and a heavier bill, the omnivorous birds are larger than the common crow, appearing more like a raven.

More than two dozen juvenile 'alala that were raised in captivity were released from 1993 to 1998. However, 21 died, and the remaining six were recaptured and placed with the captive flock. Some that died were found to have toxoplamosis, a disease spread by feral cats.