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Wild Things

The weird and wonderful in the natural world

Sarah Zielinski

Wild Things


Wild Things

Kauai’s native forest birds are headed toward extinction

iiwi, a Hawaiian honeycreeper

The iiwi is one of six species of forest birds, all honeycreepers, that are endemic to the island of Kauai — and disappearing fast.

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Hawaiian honeycreepers are a marvel of evolution. Millions of years ago, some finches arrived on the Hawaiian Islands and began to diversify. As the Pacific Plate moved over the Hawaiian hotspot and new islands formed and others shriveled away, these colorful songbirds evolved into more than 50 species that differed so much in what they ate, where they lived and how they looked that it took scientists quite a while to figure out that they were all related.

More than half of those species are now gone. “Many extinctions took place when the islands were first settled by Polynesian people,” notes Helen James, who, as curator of birds at Smithsonian’s National Museum of Natural History, has studied the birds’ evolutionary history. Then Westerners arrived and bird populations started to disappear more quickly due to a combination of threats, including habitat loss, introduction of invasive species and the arrival of diseases such as avian malaria.

Bird populations on Hawaii’s oldest island, Kauai, have been hit especially hard. Kauai lost at least eight species of honeycreepers — as well as several other “marvelous species” of birds, James notes — before people began keeping good records of the island’s fauna. And now a new study warns that the birds’ situation will get worse — and soon. The honeycreepers that are left on the island are declining fast, and some species could disappear in as little as a decade.

Eben Paxton of the U.S. Geological Survey Pacific Islands Ecosystems Research Center at Hawaii Volcanoes National Park and colleagues looked at population trends for seven species of native forest birds living on Kauai’s Alakai Plateau, the eroded crater of a long-extinct volcano. On other Hawaiian islands, only high-elevation areas have generally been cool enough to keep out the mosquitoes that spread avian diseases. But on lower-lying Kauai, its forests have tended to be cooler than similar-elevation regions on the other islands, so spots such as the Alakai Plateau have been disease-free refuges for native birds.

amakihi Or, they were. A 2014 study found that disease prevalence in birds had more than doubled there between 1994-1997 and 2007-2013. Climate change had warmed the plateau enough that disease-laden mosquitoes could spread.

In the new study, Paxton and his colleagues found that six of seven native forest birds surveyed (an eighth proved too wily for scientists to accurately count) are rapidly disappearing and their ranges contracting. All six are honeycreepers, and four are now found only in small, remote parts of the plateau. Fewer than 1,000 Akekee and fewer than 500 Akikiki remain, the team reports September 2 in Science Advances.

“If native species linearly decline at a rate similar to or greater than that of the past decade, then multiple extinctions are likely in the next decade,” the team writes.

James says that she hopes the new findings will be a call to action. “Their data show alarming declines in population and geographic ranges of endemic Hawaiian honeycreepers on the island of Kauai,” she says. The birds’ extinction “would be a tremendous loss.”

Even without avian diseases and climate change, the honeycreepers still face threats from habitat loss, introduced predators and competition with non-native birds (some of whom, such as the Japanese bush-warbler, are thriving on the plateau, the study finds). Reducing those threats could buy the honeycreepers some time to adapt to the growing threat of disease. Scientists can also help by developing genetically modified mosquitoes and figuring out why honeycreepers are so susceptible to avian malaria — and how to protect them from it, James notes.

“The Hawaiian honeycreepers are a classic example of adaptive radiation in animals, second only to Darwin’s finches,” she says. Losing Kauai’s endemic honeycreepers “would definitely cost us in terms of our opportunities to study, understand and appreciate nature.”

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By Sarah Zielinski 9:34am, September 9, 2016
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Tail vibrations may have preceded evolution of rattlesnake rattle

By Sarah Zielinski 7:00am, August 31, 2016
The rattle on a rattlesnake evolved just once. A new study contends it may have come out of a common behavior — tail vibration — that snakes use to deter predators.
Animals,, Evolution

The weird mating habits of daddy longlegs

By Sarah Zielinski 11:00am, August 22, 2016
Scientists studying the sex lives of daddy longlegs are finding there’s a lot of diversity among this group of arachnids.
Animals

Lizard mom’s microbiome may protect her eggs

By Sarah Zielinski 5:19pm, August 16, 2016
Striped plateau lizard moms don’t do any parenting beyond laying eggs. But they may convey protection from pathogens with help from their microbiome.
Animals,, Ecology

Capybaras may be poised to be Florida’s next invasive rodent

By Sarah Zielinski 11:30am, August 12, 2016
Some capybaras have escaped their owners in Florida. Others have been set loose. Now there are fears the giant rodents could become established in the state.
Animals

Bird-friendly yards have a major downside — for birds

By Sarah Zielinski 7:00am, August 3, 2016
Vegetation and feeders bring birds into our yards. But those lures also bring more birds to collide with the windows in our homes.
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Pup kidnapping has a happy ending when a seal gets two moms

By Sarah Zielinski 12:48pm, July 29, 2016
A female fur seal kidnapped another seal’s pup. But this turned out to be a positive the young seal, scientists found.
Oceans,, Ecology

Sea ice algae drive the Arctic food web

By Sarah Zielinski 1:00pm, July 26, 2016
Even organisms that don’t depend on sea ice depend on sea ice algae, a new study finds. But Arctic sea ice is disappearing.
Animals

Tiny ants move a ton of soil

By Sarah Zielinski 9:00am, July 20, 2016
For the first time, scientists have quantified how much soil ants move underground.
Animals,, Evolution

For jaguars, armored prey is no obstacle

By Sarah Zielinski 9:00am, July 15, 2016
With big heads, thick teeth and strong muscles, jaguars have evolved to take on dangerous prey, often animals covered with thick armor.
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