Following up on the success of its alala reintroduction program, the state and its conservation partners say they plan to establish a second population of the endangered kiwikiu on the leeward slopes of Haleakala.

The plan calls for the relocation of 20 kiwikiu, also known as Maui parrotbills, to the Nakula Natural Area Reserve in October or early November.

While kiwikiu were once found all across Maui, including the drier leeward slopes of Haleakala, the current population of fewer than 300 birds is confined to the high- elevation rainforest on the windward side of the Maui mountain.

Considered Maui’s most endangered forest bird, the kiwikiu’s current habitat is actively managed behind fencing that holds back destructive pigs, deer and goats.

But scientists say introduced predators and avian diseases remain a threat.

“As long as the entire population is restricted to one area, the species will remain vulnerable to extinction,” Hanna Mounce, coordinator of the Maui Forest Bird Recovery Project, said in a media release. “Without a second population, it is only a matter of time before we lose this critically endangered species.”

The U.S. Fish and Wildlife Service 2006 Hawaiian Forest Bird Recovery Plan recommended creating a second population of kiwikiu.

The 1,420-acre Nakula Natural Area Reserve was established in 2011, in part anticipating the release of the yellow and olive-green Hawaiian honeycreeper with a parrotlike beak. The bird was given the Hawaiian name “kiwikiu” in 2010.

The Maui Forest Bird Recovery Project, a program of the Pacific Cooperative Studies Unit of the University of Hawaii at Manoa, and the state Division of Forestry and Wildlife have been working with government and private landowners to restore the Nakula reserve for a number of years.

The project, described as being part of a larger effort with the Leeward Haleakala Watershed Restoration Project, began with fencing and removal of feral animals, followed by the planting of 250,000 native trees, including koa, ohia and 17 other species.

As the release approaches in the fall, some of the kiwikiu will be moved to Nakula from their current forest homes in East Maui, while others will come from San Diego Zoo Global’s Maui Bird Conservation Center.

Using techniques developed for previous species reintroductions, the relocation teams have built a series of platforms to hold small release aviaries in the Nakula reserve. Here the birds will spend time adjusting to their new surroundings before being released.

Once the kiwikiu are released, the teams will track movements, feeding patterns and behavior.

The state and San Diego Zoo Global combined to reintroduce the Hawaiian crow to the wilderness of the Puu Makaala Natural Area Reserve two years ago. Although the first release was aborted, two more have been successful, and there are now 21 alala in the wild.