Swiss Army knife of the Hawaiian Islands—how an endangered bird drills into trees to find food

The Hawaiian Islands are home to an endangered bird called the akiapōlāʻau, which has evolved a unique beak resembling two different bird beaks combined. A new study published in the journal Ornithology offers a detailed examination of this bird's anatomy, revealing that its beak is not the only adaptation aiding its foraging. The entire body, from its ankles to its head, is specially developed for drilling into trees to extract food.

Researchers found that the akiapōlāʻau's upper and lower beaks serve distinct purposes, functioning like separate tools: the upper beak is long and slender to extract insects from small crevices, while the lower beak is short and stout for gouging into wood. This bird exhibits features not seen in any other birds, earning it the nickname "Swiss Army knife of the Hawaiian Islands."

Its lower bill and upper beak are distinctly different, allowing it to occupy a niche similar to woodpeckers, which never reached the Hawaiian Islands. The study highlights the bird's exceptional ankle and foot structure, which enables it to use its entire body weight to penetrate trees, unlike woodpeckers that rely mainly on neck muscles.

Conservationists emphasize the urgent need to protect the akiapōlāʻau, as the species' wild population has dwindled to fewer than 2,000 individuals on the northeastern slope of one mountain in Hawaii.