Newspaper article The Christian Science Monitor

Hawaiian Bird Stages Mysterious Comeback

Newspaper article The Christian Science Monitor

Hawaiian Bird Stages Mysterious Comeback

Article excerpt

Nature rather than man may be saving a small, rare green bird in Hawaii from the brink of extinction. Until 10 years ago, the Hawaiian Amakihi could live only in high-elevation forests after it was driven almost completely from its primary habitat in lower regions by the spread of avian malaria. But scientists have discovered the Amakihi is thriving and breeding once again in its original habitat. What's unusual is that the resurgence is happening outside of any captive-breeding program or other human intervention.

Now scientists are trying to figure out why. Understanding how the Amakihi are surviving avian malaria may hold the key to saving other Hawaiian bird species, many of which are increasingly threatened by mosquito-borne illnesses.

The Amakihi's recovery could also have implications for North American bird populations, which struggle with another mosquito- transmitted disease, the West Nile virus.

"It is ... rare to witness the evolution of resistance to the disease and the 'comeback' of a population of birds," says biologist Patrick Hart, a member of the US Geological Survey (USGS)research team.

At least 71 species and subspecies of Hawaiian birds existed when Western explorers arrived in the Hawaiian Islands in 1778. Now, however, 76 percent of the Hawaiian bird species are either extinct or endangered, and several others are showing significant population declines.

Much of this ecological devastation is attributed to disease- carrying mosquitoes. Until 1826, Hawaii was free of mosquitoes, which were brought to the islands by Western traders and settlers. Native birds essentially disappeared from lowland forests, where the climate is favorable for mosquitoes.

Today most Hawaiian bird species survive only in high-elevation forests, where mosquitoes are rare. Amakihi are most common in native forests above an elevation of 2,000 feet, where they feed on insects and flower nectar. But at lower levels, these birds have adapted to survive, and now are thriving - despite high rates of malarial infection (60 to 90 percent).

So why is this happening?

"Perhaps the most tantalizing [hypothesis] is that the Amakihi has undergone natural selection and has evolved some level of resistance to avian malaria," says Bethany Woodworth, a wildlife biologist with the USGS. …

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