Hawai'i's largest endemic tree, with its sickle-shaped leaves, has reclaimed some of its former territory over the last two decades.

Conservationists and small timber harvesters have replanted koa on thousands of acres on the Big Island and Maui, increasingly fencing out the cattle, pigs and goats that forage on koa bark and seedlings.

They hope replanting the slow-growing trees can help restore the feeding and nesting grounds of endangered native forest birds and quench demand for valuable koa timber, with a scarcity and a lustrous grain that rank it among the world's most expensive woods. A tree can take 40 years to mature.