Wave of Hawaiian Bird Extinctions Stresses the Islands’ Conservation Crisis

On an early morning in 1975, H. Douglas Pratt awoke in his tent pitched on Hawaii’s Alakaʻi Plateau to the song of the Kauaʻi ʻŌʻō. The bell-like vocal clarity was unmistakable, though the bird was extremely rare; the species was listed as federally endangered in 1973, with an estimated population of 36 surviving individuals. “I can still recall the hair standing up on my neck,” the retired ornithologist says. “Their song can be described as both haunting and evocative.”

Pratt was lucky to hear the Kauaʻi ʻŌʻō, and was one of the last people to do so. The mostly black bird with tufts of striking yellow feathers on its thighs was last seen in 1985 and last heard in 1987. No one will ever hear it sing in the wild again. On Wednesday, the U.S. Fish and Wildlife Service (USFWS) declared 23 species across the United States extinct and proposed they lose protections under the Endangered Species Act (ESA). Eight of those species, including the Kauaʻi ʻŌʻō, are Hawaii forest birds. The other seven are the Kauaʻi ʻAkialoa, Kauaʻi Nukupuʻu, Kāmaʻo or Large Kauaʻi Thrush, Maui Ākepa, Maui Nukupuʻu, Kākāwahie or Molokai Creeper, and Poʻouli. The Ivory-billed Woodpecker and Bachmann’s Warbler are also extinct, according to the agency.

Half of the newly extinct Hawaiian birds were once found only on Kauaʻi. Three were Maui endemics. One was resident to Molokaʻi. They all were driven extinct for similar reasons: destruction of forest habitat, invasive predators, and avian malaria, a mosquito-borne disease introduced to the Islands within the last few centuries.

“Hawaii has been in a conservation crisis for a long time,” Hanna Mounce, coordinator for the Maui Forest Bird Recovery Project, says. “But admitting that these species are gone forever puts an even finer point on it.”

The Kauaʻi ʻŌʻō was the last surviving species in its family of nectar-eating songbirds; the entire bird family is now extinct. The Kāmaʻo, a dark brown fruit-eating thrush closely related to the mainland Townsend's Solitaire, was considered extremely abundant in Kauaʻi's wet forests in the early 1900s. It was last sighted in the late 1980s.

Six of the eight species belong to a family of passerines endemic to Hawaii and known as honeycreepers, recognized for their astonishing process of rapid evolution. From one ancestral species of Eurasian Rose Finches, which arrived in the Islands more than seven million years ago, more than 50 new species evolved and descended. They came in shades of yellow, green, orange, and red, and ranged in size from four to eight inches in length.

What’s most striking about honeycreepers is their variety of bill sizes and shapes. One species had a short, stout bill used to crush seeds and snails; another a multi-tool beak with an upper mandible twice as long the lower—the lower used to hammer bark while the upper slipped into crevices and holes to hook insects. Some had crossed bills used to pry open leaf buds to reveal insect morsels inside. Still others, with long decurved bills co-evolved with tubular flower species, traded nectar for pollination.

Now, with these six extinctions, only 17 of the more than 50 honeycreeper species that once lived remain, according to Michelle Bogardus, USFWS Maui Nui and Hawaii Island Team Leader. But several of those considered still present, including the ʻŌʻū, Oʻahu ʻAlauohio, and Olomaʻo, have not been seen in recent decades. Their status will be reviewed again by USFWS during their next five-year review period, a required provision of the ESA and the path to de-listing.

“Hawaii is the epicenter of the global loss of biodiversity,” Lisa “Cali” Crampton, project leader with the Kauai Forest Bird Recovery Project, says. “It's not just that we have lost these individual species—we have lost some plant species that depend on them for pollination and seed dispersal, making our entire forest less robust and resilient.”

“They also had tremendous cultural importance, woven into the fabric of Hawaiiian life,” she adds.

Pratt wasn’t surprised at the USFWS news. None of the eight Hawaiian species have been seen in decades. Some were likely extinct when the ESA was passed in 1973. One, the Kaua’i Nukupuʻu, hasn’t been seen in more than 120 years. Still, he expressed disappointment and frustration over the news, as did a cascade of other researchers, that more wasn't done sooner to save these birds. But maybe this news will change that.

“Something I hope people understand is that extinction is not just the Dodo and Passenger Pigeon,” says Chris Farmer, Hawaii program director with the American Bird Conservancy. “Extinction is happening right now, and we’re about to have another major wave if we’re not careful.”

Islands are particularly vulnerable to extinctions. There’s the issue of size: Islands have a finite amount of habitat to support bird populations. On Hawaii, over the course of nearly 200 years, American and European colonists destroyed much of its already limited habitat through large-scale agriculture and development. “The first driving force of these extinctions was habitat destruction," Mounce says. "Most of our islands used to be covered by forests."

The lack of habitat also makes it highly unlikely that these eight birds are not really extinct but remain out there still. Sometimes, species are declared extinct and then rediscovered later—what are known as ‘Lazarus species.’ “Species that are rediscovered in an Amazon rainforest where there are millions of acres for them to disappear is one thing,” Mounce says. “But on Maui, with less than 50 square kilometers [19 square miles] of native forest-bird habitat, there are few places to none that these birds could be hiding in which we have not searched for many, many years now.”

Still, species resurrection does happen, even on Hawaii. Just last week, a rare fern, thought to be extinct, was rediscovered on Kauaʻi. But Mounce and Crampton are confident the birds are truly gone. Their crews have spent many years and thousands of hours combing their respective islands for any sign of them, including using playback of recorded birdsong to attract birds. “Many of these birds have loud characteristic sounds, so we would have found them if they were still around,” Crampton says. “It’s not like a plant that’s silent and immobile and so much harder to find.”

Habitat loss wasn’t the only reason for the birds’ extinction. They were squeezed from all sides by introduced predators like rats, cats, and pigs. In the case of the Kauaʻi ʻŌʻō and the Kāmaʻo, already teetering on the brink, hurricanes likely wiped out the last holdouts. Right now, mosquitoes are the imminent problem. Introduced to the Islands in the early 1800s, possibly in whalers’ water casks, avian malaria-carrying mosquitoes are spreading through Hawaiiʻs mountains and biting birds with no immunities against the disease. All it takes is one bite of an infected mosquito to kill certain honeycreepers—including two extant species, the ʻAkikiki and Kiwikiu, which hover on the brink with fewer than 150 individuals remaining in the wild.

The mosquito problem has been exacerbated by climate change; warmer temperatures allow mosquitoes to survive at higher elevations and move into the honeycreepers' last mountaintop strongholds.

Hope is not lost, Farmer insists. “We have an opportunity in our generation to save these birds and prevent more extinctions." Doing so requires mosquito-population control—an effort scientists have been pursuing for years now. Permitting and regulatory requirements take time, Farmer says, but smaller trials could happen in one to two years, with larger landscape-scale projects in two to four years.

If scientists can achieve that rapid timeline, they could get to the birds just in time. “We have two to five years to break the extinction cycle,” he says. “We have the science. We need to scale it up. But I am incredibly hopeful that we can prevent the extinction of another species on our watch.”