We lace our boots and finally walk through a pig fence and down into the forest. As we descend along the rutted two-track road, Rob picks out individual birdcalls from the scattering of tweets, chirps and trills. "'Elepaio," he says, waving up the hill, "and 'akepa," waving down the hill. He's so good at this, he can tell a bird's call from another bird mimicking its call. He points out adolescent koa trees, the sprays of horizontal juvenile leaves flattening at the stem into the vertical, sickle-shaped leaves of the adult tree. He points out a larger fallen koa that has become a nurse log to a neat row of new trees, with understory plants sheltering beneath.