Climate Change and Mosquitoes: A Deadly Combination for Hawaii's Rare Birds
For you and me, a single mosquito bite probably isn’t much more than an annoyance.
The colorful Hawaiian birds known as ‘i’iwi aren’t so lucky. For these increasingly rare birds, one mosquito nibble means almost certain death.
Mosquitoes are not native to Hawaii. The insects arrived on the islands about two centuries ago, and with them came the parasite that causes avian malaria (a different form of the disease that can affect humans). Hawaii’s birds evolved far away from either mosquitoes or avian malaria, and as a result many of them have little to no resistance to the disease.
So, Why Should You Care? The mosquito and malaria invasion of Hawaii is so bad that it has driven dozens of native birds—which exist nowhere else on Earth—into extinction. Of the 51 native “honeycreeper” bird species of Hawaii, many of which have great importance to Hawaiian culture, fewer than half remain. Many of those are endangered, some critically so.
Things are about to get worse.
According to a paper published this week in the journal Global Change Biology, most of Hawaii’s remaining native birds have retreated to high, cold elevations where mosquitoes can’t survive. That sanctuary is about to disappear. Climate change will warm those mountain habitats and make them more hospitable to mosquitoes and the deadly diseases that they carry.
According to calculations by researchers from the United States Geological Survey and the University of Wisconsin–Madison, the effect will be devastating. The ‘i’wi population could plummet by up to 90 percent by the end of the century.
Other species will also suffer. The researchers looked at infection and survival rates for other honeycreepers and found that the ‘apapane will lose about 10 to 20 percent of its population, while the common ‘amakihi will decline between 40 and 80 percent. They say the effects will be similar in other species.
Other problems will compound the effect of the mosquitoes. Hawaii’s birds have already fled to high, mountainous habitats, which themselves are at risk. “They cannot move to higher elevations because the climatologists predict that the tree line will decrease responding to the future climate change,” said Wei Liao, a postdoctorate at University of Wisconsin–Madison and lead author of the paper. “That is why we are so concerned. The birds are unique in Hawaii, and there are not many, if none at all, places to relocate them.”
The researchers calculate that the effects of climate change and mosquito migration won’t become a problem until around 2040, giving us some time to look for solutions. One important strategy mentioned in the paper would be to control the feral pigs that infest the Hawaiian Islands as they carry mosquitoes to new areas and root up the vegetation and trees that the birds need to survive. Another step would be long-term efforts to restore Hawaii’s degraded forests.
Liao’s team is looking at some of these potential solutions and malaria mitigation strategies and will soon organize a workshop to share their results with natural resource managers. Until then, maybe it’s time for Hawaii to stock up on Deet.