Often called “the extinction capital of the world,” Hawaii has experienced far more avian loss than the other 49 states combined.
Using the fossil record, scientists have identified at least 71 species and subspecies of forest birds — along with several duck, goose, rail, and flightless ibis species — that disappeared following the arrival of the Polynesians 800 to 1,400 years ago. Some were likely hunted directly, scientists believe, whereas others were done in by habitat degradation or by the rats, pigs, and dogs that the Polynesians brought with them.
Once Europeans arrived in 1778, a second wave of destruction commenced, leading to 24 additional bird extinctions (plus the unceremonious overthrow of the Hawaiian monarchy). In addition to accelerating habitat loss, Europeans and Americans introduced new and deadly avian predators, from cats and mongooses to the black rat, which, unlike the Polynesian rat, readily climbs trees to raid nests.
The newcomers also accidentally unleashed mosquitoes on the island chain, a true tropical paradise that didn’t previously have them. Outbreaks of avian pox and, starting around the 1930s, avian malaria subsequently decimated Hawaii’s famous honeycreepers, which hadn’t evolved any defenses to such diseases.
Today, only 21 native songbird species remain on the main Hawaiian islands, 11 of which are federally listed as endangered. Most are high in the mountains, where avian malaria has yet to reach, meaning locals in the populated lowlands can spend their entire lives without ever seeing a native passerine.
To make matters worse, scientists now fear yet another wave of extinctions, as climate change allows malaria-carrying mosquitoes to move farther up mountain slopes. The island of Kauai, which tops out around 5,000 feet, just above the avian malaria line, has been especially hard hit; surveys show that its bird populations have crashed over the last 10 years or so.
“If we can’t resolve the disease issue, it’s hard to see how we wouldn’t lose most of the remaining forest birds in the next few decades, or maybe even quicker,” says Eben Paxton, an avian ecologist with the U.S. Geological Survey, who specializes in the endangered forest birds of Hawaii and other Pacific islands.
With time ticking, Paxton and colleagues are studying honeycreeper genetics, as well as the bird-parasite-vector relationship, in the hope of identifying factors associated with increased immunity to avian malaria. Meanwhile, other scientists are working on various methods of experimental mosquito control, including infecting males with a bacterium that would serve as a mosquito contraceptive.
Habitat restoration, habitat protection, and curbing non-native mammals will also continue playing a role, Paxton explains.
“It’s really tough to be working so hard trying to save these birds and to have these large forces that are so difficult to control,” he says. Yet he adds that parts of Hawaii still have “vibrant, functioning bird communities” and that “as long as those places are there, the fight’s still worth fighting.”
The 10 rarest bird species on the main Hawaiian islands
Species Estimated population
Hawaiian Crow 10 (all captive-bred birds)
Oahu Elepaio 1,261
Hawaiian Coot 2,000