By Jan TenBruggencate
One of the state's leading forest-bird researchers believes the endangered Hawai'i 'akepa could face extinction in a decade or two from competition with the introduced Japanese white-eye, or meijiro.
'Akepa are among the most brightly colored birds in the Hawaiian native forest, with male plumage a blazing orange. Females are gray-green with yellow and orange tints. They feed primarily on insects.
White-eyes can be found in almost every habitat in the state. The green birds, which have a white ring around their black eyes, feed on insects, fruit and nectar.
The two birds' breeding seasons overlap, and University of Hawai'i zoologist Leonard Freed said it appears the 'akepa is losing the battle for food at a time when they need the most nutrition. 'Akepa breeding success and chick survival rates have plummeted in the Big Island's Hakalau Forest National Wildlife Refuge during the same five-year period in which white-eye populations have expanded dramatically there, he said.
There are perhaps 5,000 'akepa left in isolated regions of the Big Island, but prospects are bad, according to Freed. Both adult birds and surviving chicks are being found with low body-weights, indicating they are not getting enough nutrition.
Under food stress, not only are the birds producing fewer surviving young, but the survivors have a sex ratio of 10 males to one female, which will reduce the population's ability to recover. Adult females are dying at a higher rate than males, perhaps due to the energy cost of producing young. "The number of breeding birds in our census area is down by one-third," Freed said. "If something isn't done, the 'akepa will go extinct."
Freed and fellow researchers have proposed to the Hakalau Forest National Wildlife Refuge that mist-nets be used to remove some white-eyes for a season, to determine whether that will allow the 'akepa nesting to resume at normal levels.
Refuge manager Dick Wass said his agency is skeptical of Freed's conclusions and is seeking comment from other scientists. He wants to see more data, including the results of a forest-bird census, before allowing white-eye netting.
"He's raised a red flag and we're looking at this issue, but there are a lot of other ways to collect data," Wass said.
Freed will discuss his findings at a Hawai'i Audubon Society meeting from 6:30 to 8:30 p.m. Nov. 14 at the UH St. John Lab at 3190 Maile Way in Manoa.
If you have a question or concern about the Hawaiian environment, drop a note to Jan TenBruggencate at P.O. Box 524, Lihu'e, HI 96766 or firstname.lastname@example.org. Or call him at (808) 245-3074.