It was a tough year for the Maui Forest Bird Recovery Project. Project manager Hanna Mounce and her field crew had spent the decade prior to 2019 rehabbing a forest for the endemic kiwikiu, or Maui parrotbill. Fewer than three hundred of the plump yellow honeycreepers clung to survival on the windward slope of Haleakala. Mounce planned to establish a second kiwikiu population in a protected reserve on the leeward side of the mountain. Her team released thirteen birds into the reserve and, tragically, within a month all but one died. Autopsies revealed the culprit: avian malaria.
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(ABOVE, left) Mosquito-borne avian malaria pushed Hawaii’s rare and endemic native birds, like the iiwi and the amakihi seen on pages (BELOW), to the edge of extinction. Now scientists are testing a novel approach to controlling the pestiferous mosquitoes: breeding and releasing larvae that produce infertile eggs (ABOVE, right).
Ever since mosquitoes arrived in the Islands in 1826, Hawaiian birds have succumbed to mosquito-borne plagues-avian malaria and pox. Of the fifty-plus endemic-that is, found nowhere else in the world-honeycreeper species that once filled Hawaiian forests, only seventeen remain. These survivors inhabit a narrow belt of forest above five thousand feet in elevation, where it's too cold for mosquitoes and the diseases they carry. But rising temperatures are pushing mosquitoes up the mountain, and soon there will be no safe place left for the birds. Not in twenty-five years, as previously thought, but in two or three.
After the kiwikiu translocation failed, Mounce confronted a stark choice: Eliminate mosquitoes or say goodbye to the birds. With state and federal support, she reached for a biological control that had been used successfully worldwide to combat mosquitoes carrying Zika, dengue and yellow fever. Wolbachia is a bacterium that naturally occurs in 60 percent of the world's insects. When mosquitoes with different, incompatible strains of Wolbachia mate, the resulting eggs don't hatch. "It's basically mosquito birth control," says Mounce.
In the fall of 2023, Mounce's team will release a batch of male mosquitoes carefully reared and inoculated with Wolbachia into a small plot of East Maui rainforest. She's blunt about the stakes. "We don't have any other way to control avian malaria," she says. "This can work. But we have to invest in it." Suppressing mosquitoes is an expensive undertaking but, if successful, will radically expand the honeycreepers' habitat. "We could quadruple the amount of birds we have," says Mounce. As Emily Dickinson said, hope is the thing with feathers.
