June 5, 2009 | 1
Darn those mosquitoes. First we learn this week that they have adapted to feed on reptile blood on the Galápagos Islands, putting several rare species there at risk. Now we hear that they are also threatening Hawaii’s endangered birds, and may soon be pushing several species closer to extinction. (Not to mention the usual things they do, such as transmit malaria.)
Hawaii was blessedly mosquito-free until about 1820, when the pesky insects first hitched a ride on Western ships and found a whole new buffet table opened up to them. With mosquitoes came disease and exposure to species that have no immunity or protection from skeeter-borne illnesses.
Take the ‘I’iwi Honeycreeper (Vestiaria coccinea), for example. This rare bird is so susceptible to avian malaria that a single mosquito bite is fatal 90 percent of the time, according to a report published in the Journal of Avian Medicine and Surgery. The ‘I’iwi has already disappeared from one Hawaiian island, and is now rare on two other islands.
The ‘I’iwi is just one of Hawaii’s honeycreeper species, but its cousins aren’t doing any better. "Of 41 honeycreeper species and subspecies known since historic times, 17 are probably extinct, 14 are endangered, and only 3 are in decent shape," according to a post on Science Daily. Avian malaria is blamed for much of this decline.
And here’s where it gets worse. Hawaii’s honeycreepers can avoid mosquitoes by living at high elevations, above 4,000 feet (1,200 meters), where cool temperatures are inhospitable to the blood-sucking insects, but climate change may soon give mosquitoes a boost and an invitation to the honeycreepers’ mountain habitat.
Temperatures in Hawaii’s mid-elevation forests are projected to rise 3.6 degrees Fahrenheit (2 degrees Centigrade) in the next 40 years, a change which would virtually eliminate the low-temperature areas that the honeycreepers depend upon for their survival. “With this kind of temperature change, about 60 to 96 percent of the high-elevation disease refuges would disappear,” according to Carter Atkinson, lead author of the Avian Medicine study and a microbiologist for the U.S. Geological Service.
So how to protect the honeycreepers and other species? Hawaii is already taking steps to reduce the range of other invasive species, like feral pigs and goats, who help to spread and feed mosquito populations, according to a report in Hawaii’s Star-Bulletin. Hawaii also has an entire area of its Department of Health, the Vector Control Branch, devoted to "control and prevent the spread of insects, rodents, or other organisms which are able to transmit infectious agents of disease."
Images: Mosquito by Bulent Fahri Ince via Stock.xchng and ‘I’iwi Honeycreeper, Carter Atkinson, U.S. Geological Survey