A critically endangered bird species on the Big Island may be beginning to rebound after extensive habitat restoration projects.
’Akiapola’au, a Hawaiian honeycreeper endemic to Hawaii Island, is one of several endangered native bird species in the state. Only about 1,900 of the species are believed to still exist. An endangered species, there are only around 1,900 ’akiapola’au remaining.
One ’akiapola’au named Christmas — because of the red-and-green leg band put on him by researchers to identify him —is 9 years old and believed to be the oldest living ’akiapola’au in the wild.
The species, which uses its long, curved beak to fill the niche occupied by woodpeckers, feed on insects from the branches of native trees and nectar from flowers shaped like their bills and also look for larvae on the forest floor. But they are also exceptionally vulnerable to avian malaria, a mosquito-borne illness that threatens all species of Hawaiian honeycreepers.
“1,900 birds seem like a high number, but ’akiapola’au have been on the endangered species list since 1967 because of their low population and reproductive numbers, a fragmented population and habitat loss,” said Department of Land and Natural Resources researcher Bret Nainoa Mossman. “However, aggressive forest restoration, predator control, and removal of feral ungulates in the natural area reserve and by neighboring watershed partners is painting a really heartening story.”
’Akiapola’au population increases can be attributed to those decades of forest management and restoration, and recent efforts to reduce feline and rodent predators.
Tens of thousands of koa trees have been planted at the Pu’u Maka’ala Natural Area Reserve and on neighboring lands, but it takes roughly 10 years for them to become good bird habitat. Mossman says many of the koa were planted in the last seven or eight years, but already ’akiapola’au and ’alawi are starting to use the koa trees.
One of Christmas’ offspring has moved from the north side of the Natural Area Reserve to the south side, where 10,000 koa trees have been planted.
“It’s rewarding to see an ’akiapola’au we banded as a baby in this kipuka, and he has now settled in a completely different place,” Mossman said. “So, we’ve seen three generations of ’akiapola’au, in the five years I’ve been working here.
“It’s been really nice to see that we can keep tabs on these birds, track their relationships, and observe how they’re taking advantage of what we’ve created for them,” Mossman went on. “Something more to celebrate this holiday season.”
Mossman added that another bird species, the ’oma’o or Hawaiian thrush, is helping to restore the forest habitat by eating fruit and spreading seeds.
But even though the ’oma’o is less critically endangered than honeycreeper species — there are an estimated 100,000 on the Big Island, they are still threatened by predators, although Mossman said they appear to be somewhat resistant to avian malaria.
“They seem to be able to live with the disease, but malaria coupled with predators is still driving them to decline in numbers,” Mossman said.
But Mossman concluded that every species and every bird is teaching researchers lessons that may prove helpful in the continuing battle to reduce mosquito populations in their habitats and save native bird species from the brink of exinction.