Once-endangered 'amakihi bird thrives in state's lowland forests

By Timothy Hurley
Advertiser Staff Writer

Once thought to be incapable of surviving in Hawai'i's lowland forests, the 'amakihi forest bird is not only living there once again but actually thriving in some low-elevation areas, scientists have discovered.

A team of researchers at the Pacific Island Ecosystems Research Center has found the small, yellow-green honeycreeper living and breeding in low-elevation forests of the Big Island in densities two to three times those found at disease-free high elevations, despite high rates of malaria infection.

In addition, the data show an increase in range and abundance of 'amakihi at low elevations in the past decade.

The discovery is remarkable because most native Hawaiian forest bird populations were decimated after the accidental introduction of mosquito-transmitted avian malaria and pox in the last century. Many native birds simply vanished from lowland forests, where the climate is favorable for mosquitoes and disease transmission, while some became extinct.

In recent years, however, there have been an increasing number of sightings of 'amakihi in the lowland forests of the Big Island and Moloka'i, and even in suburban areas of O'ahu, including 'Aina Haina, Manoa, and Nu'uanu.

Now, scientists have documented the low-elevation comeback, proving that the bird with the sewing-machine trill isn't just visiting lowland regions but living and breeding there. Blood samples taken from the lowland 'amakihi indicate that many of the birds got malaria, survived and became immune.

Patrick Hart, a University of Hawai'i and U.S. Geological Survey researcher, said the data suggests the 'amakihi is evolving resistance to the introduced diseases, with their chances of survival boosted by the abundance of food and breeding conditions found at lower elevations.

Scientists working in the sea-level forest in Puna visited the same bird survey locations where no 'amakihi were seen 10 years ago, Hart said. But surveys last year and last month found 'amakihi at 40 percent of the 91 forest survey spots.

Hart has lived in the 'ohi'a forest of Hawaiian Paradise Park on the coast of Puna for seven years. For the first five years, he did not hear the 'amakihi.

"Now I hear and see them all over the place," he said.