Posted on: Monday, July 19, 2004

HAWAI'I'S ENVIRONMENT
Native bird makes comeback

By Jan TenBruggencate
Advertiser Columnist

With almost all native Hawaiian forest birds in serious decline, federal researchers on the Big Island were stunned to find that one, the greenish-yellow 'amakihi, has within the past 10 years developed resistance to bird malaria and is fast expanding its numbers.

"It gives us hope that other species will develop (a tolerance for avian malaria)," said zoologist Pat Hart, who works with the U.S. Geological Survey and the University of Hawai'i's Pacific Cooperative Studies Unit.

His co-worker, Carter Atkinson, said malaria is believed to be one of the most significant disease threats to native birds, most of which have little or no resistance to it. One reason many native birds are now restricted to the high forests is that mosquitoes are not found there.

Atkinson said scientists went to lowland Puna a few years ago and were shocked to find 'amakihi fluttering around in significant numbers. Laboratory studies on the birds showed they can get malaria but don't get as sick as other birds.

The Puna birds measure slightly smaller than their upland cousins, and genetic studies confirm that the Puna birds are not simply mountain birds that migrated down to the coastline, but descendants of birds that have been isolated from the upland birds for some time.

"I think that the birds have always been there in really low densities, but 10 years ago surveys at 90 locations found no birds. Now we see birds at half those locations," Hart said.

Atkinson said there are plenty of non-native birds in the region, but the 'amakihi "are competing with them and doing well."

Another native, the red 'apapane, has long shown some tolerance to avian malaria and is also seen in the lower Puna forests, but it is far less numerous than the 'amakihi.

Hart said the 'amakihi may show significant evolution of malaria resistance in part because it produces more chicks per year than most other native forest birds, giving it a better opportunity to evolve resistance to threats.

They found the 'amakihi centered on the best patches of remnant native 'ohi'a forest in Puna.

"It highlights the importance of low-elevation forests," Atkinson said. "They appear to be crucibles for evolution."

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, e-mail jant@honoluluadvertiser.com or call (808) 245-3074.