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Rats, disease, and climate change are threatening Hawaii's spectacular songbirds

Hawaii’s answer to the cardinal is a perfect, scarlet, nectar-sipping beauty called the ‘I’iwi — but you should see it soon, if you want to see it at all. The ‘I’iwi and its extremely rare relatives are being wiped out by mosquitoes, climate change, and rats, a new study says.

Six species on the island of Kauai are in danger of going extinct

The ‘I’iwi belongs to a family of brightly colored songbirds called the Hawaiian honeycreepers, which are unique to the remote Hawaiian archipelago. They descended from a small group of finches that arrived sometime between 7.2 and 5.8 million years ago. New volcanic islands popping up over time gave the birds new environments to adapt to. Different groups found different food sources: snails, seeds, nectar. And they developed highly specialized beaks to better chow down; the ‘I’iwi, for instance, has a curved straw for sipping nectar.

Because the Hawaiian islands are so distinct, more than 50 species of honeycreeper evolved. But the conditions that set the stage for their spectacular evolution might also mean their end. Today, only 18 species remain. Of the survivors, six of them on the island of Kauai are in danger of going extinct — possibly within the next 10 years, according to a report published today in the journal Science Advances.

“This study showed us two things: one, that the ones we already knew were in trouble were in even worse trouble than we thought — like, much worse trouble,” says Lisa “Cali” Crampton, a co-author of the study and project leader with the Kaua’i Forest Bird Recovery Project. “And two, species that we thought were doing okay were actually now in trouble. So it was a really worrisome finding.”

An ‘I’iwi on the Alaka’i Swamp Trail, Kauai. (Courtesy of Jim Denny)

“It’s very hard to see a way that things are going to end well”

Isolated island ecosystems mean that honeycreepers have nowhere to run when conditions change, like when mosquitoes arrived in the 1800s. At one time, the cool, elevated Alaka’i plateau on Kauai was a refuge from the blood-sucking machines that transmit deadly (to birds) avian malaria and avian pox. But rising temperatures let the mosquitoes breed at higher and higher elevations. With so few birds within a species, it’s unlikely there is enough of a genetic mix in the population for them to evolve resistance to the diseases.

Preserving the honeycreepers and Kauai’s other native bird species is about more than keeping unique creatures from disappearing entirely. They keep the forest’s bugs under control, spread seeds, and pollinate plants. Losing them would mean even more damage to an already fragile forest ecosystem.

Mosquitoes aren’t the only threat. When people arrived in the Hawaiian Islands, they brought rats, which chow down on honeycreeper eggs, as well as adult females. These birds evolved without the threat of hungry rodents, so birds incubating their eggs don’t know to flee when a rat comes sniffing. Eating the eggs alone is bad enough, but killing an adult female is worse — it eliminates any future young she might produce, in addition to the eggs that already existed.

“This is the kind of thing that we’re going to see more and more of in our lifespan.”

The six species of honeycreeper on Kauai may soon go extinct if their numbers continue to fall at a similar rate as they have been for the last 10 years. For one species of honeycreeper, only 468 birds currently remain. For another, less than 1,000.

“It’s very hard to see a way that things are going to end well, and it’s going to happen in a relatively short period of time,” says Carl Bergstrom, an evolutionary biologist with the University of Washington in Seattle who was not involved in the study. “This is the kind of thing that we’re going to see more and more of in our lifespan.”

But Crampton and her colleagues are trying to combat the losses. They’re collecting eggs from two wild species of honeycreeper to hatch them safely in captivity, away from diseases and hungry rodents. The goal is to start a captive breeding population that would act as a literal nest-egg if a disaster were to strike and wipe out the wild birds. They’ve also set 300 rat traps around the trees where the honeycreepers nest, to discourage invaders. Unlike traps in your kitchen cabinets, these automatically reset — so a person doesn’t have to trek out onto the Alaka’i Plateau to reset the trap each time it catches a rodent. Both of these are important steps, but neither can stop the warming climate and growing spread of mosquito-borne diseases.

“To me, it’s a scandal that we don’t pay more attention to native Hawaiian forest birds,” Helen James, a vertebrate zoologist at the Smithsonian Museum of Natural History, told The Verge in an email. “These species are not just ‘endangered.’ Rather, they are clearly going to become extinct in short order if we don’t do more for them.”


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