ix thousand feet up on the flank of Mauna Kea, Jack Jeffrey and I lurk in the shrubbery near an ancient ohia tree. Its trunk bears thousands of small scars, the legacy of generations of akiapola'au that have drilled through the bark to harvest sap. Affectionately known to Hawaiian ornithologists as the aki, the bird is one of the rarest creatures on earth.
My keister has gone numb from the long sit on the forest floor. But my companion looks completely at home. Jeffrey is a senior wildlife biologist at the Hakalau Forest National Wildlife Refuge on the Big Island of Hawaii, and like many in his profession he has the knack of staying relaxed and vigilant at the same time. My attention wanders, and when Jeffrey nudges me I catch just a glimpse of an aki's black-masked face before the bird vanishes, hidden in low-lying greenery. "Don't move," Jeffrey whispers. "Just wait."
After long minutes, the aki rematerializes on the trunk of the ohia, just at my eye level. The bird is a small bundle of yellow feathers -- a male. It opens its beak, raising its long, curved upper bill out of the way, and jabs its sharp mandible through the bark, drawing out a bubble of sap. The upper bill flexes at a ludicrous angle to meet with the much shorter mandible, collecting the sap in a dainty motion. The aki appears to wear an animated pocketknife on its face, the tweezer and awl attachments both unfolded.
I shift my weight and the aki shuts its mouth and turns to face us. Our cover is blown. Viewed head-on, the bird's wacky beak appears suddenly elegant, and its expression is one of annoyance. A beat of hesitation, and it flies off into the gray-green canopy of the ohia forest, spangled with red blossoms and rustling with eccentric birds that live only in Hawaii.
Jeffrey slaps me on the shoulder. "Wasn't that great?" he says. "Did you catch that look when he noticed us?" Jeffrey's amiable grin morphs into a glaring pout that captures the aki's essence. Somehow his long nose even reminds me of that weird bill.
After the aki flies off, we linger beneath the ohia tree where the bird had landed, studying the close-set rows of holes drilled in the bark. Jeffrey and his colleagues only recently discovered that the aki is a sap eater. For decades, scientists believed that akis dined only on insects and foraged almost exclusively in the soft wood of dead or dying branches of koa, stripping away the bark and feasting on the larvae of beetles and moths.
No true woodpecker ever blundered across the sea to Hawaii, and the aki, descended from a seed-eating finch, evolved to fill the woodpecker's niche. Like the familiar woodpeckers of the mainland, the aki throws the full force of its body into the blows it strikes against a tree, making a rat-a-tat sound that carries through the forest. But the aki hammers away using just its stout lower bill. Only after a hole is drilled does the fragile, flexible upper bill come into play, probing beneath the bark to find larvae or flexing to capture a bead of sweet sap.
Young akis stay with their parents for up to a year after they fledge. In the world of small songbirds, this is a long childhood. Jeffrey believes it takes the birds that long to learn how and where to use their complicated bills. He's watched aki parents forage in front of their offspring, then move aside and wait for the young ones to follow suit.
Jeffrey has found about a hundred "aki trees" in Hakalau. These trees are always ohias, and they always bleed sap much more readily than most. For unknown reasons, these few trees -- about one in every 10,000 -- pump their internal fluids at high pressure and leak sap rapidly when punctured by an aki's bill or a biologist's pocketknife. Aki parents will lead their young to these trees.
"It was dogma that akis feed in koa trees and eat only bugs, not sap," explains Jeffrey. "But as I watched them, it became obvious that they were eating ohia sap. Using a completely different bill structure, the aki takes it like a sapsucker."