AILSA CHANG, HOST:
Now to the remote Aleutian Islands in the Bering Sea, off the coast of Alaska. About a decade ago, people living there noticed something was missing. A once-abundant seabird seemed to be vanishing. Now, wildlife researchers say they witnessed something unprecedented. Sofia Stuart-Rasi reports from member station KUCB.
(SOUNDBITE OF WAVES CRASHING)
SOFIA STUART-RASI, BYLINE: On a gray, cloudy day, waves crash against a rocky beach on the island of Unalaska. Megan Dean grips her binoculars against the chilly sea breeze, counting birds bobbing in the bay.
MEGAN DEAN: One, two, three, four.
STUART-RASI: She's making sure she adds them all up before they dive underwater.
DEAN: Ten more black scoters. We have a couple of cormorants.
STUART-RASI: Dean is part of the National Audubon Society's annual Christmas Bird Count. Volunteers across the country document every bird they spot in their local area. It helps scientists track changes in bird populations.
DEAN: It's good just to get out in the winter and, like, have a...
STUART-RASI: A reason?
DEAN: ...Greater purpose. A good citizen science project to get you through the dark days.
STUART-RASI: Unalaska is a birder's paradise - home to species like bald eagles, tuft puffins and rosy-finches. But a notable bird has been missing the past few years - the common murre, a medium-sized black and white sea bird with a long, pointed bill. Not a single common murre was spotted in Unalaska's Christmas Bird Count this winter, which is alarming because locals used to count hundreds, sometimes even thousands of them just before 2013. They're crucial for cycling nutrients through the Bering Sea. Suzi Golodoff compiles Unalaska's annual Christmas Bird Count and has spent nearly 50 years observing the island's birds.
SUZI GOLODOFF: Sometimes you see small populations of birds that become more and more vulnerable, and they become extinct, and you can sort of see how that would happen. But when a bird like a murre is hit, I mean, you know something's really haywire in the big picture.
STUART-RASI: Alaska is known to be home to 8 million common murres across the state - a quarter of the species' world population. But that's not the case anymore. Golodoff says the common murre started washing up on beaches all over Alaska.
GOLODOFF: You know, people who picked up these birds and started examining them, they could see that these murres were starving. They were just starved, emaciated.
STUART-RASI: People were even noticing that the seabirds were following rivers to inland Alaska looking for food. They got in touch with the U.S. Fish and Wildlife Service, where Heather Renner is a biologist.
HEATHER RENNER: People are on the ground, living with these wildlifes, living close to them, and that information from the people who live near them is really urgent.
STUART-RASI: Renner and other experts look back at 50 years of data from both researchers and citizen scientists. They pieced together their findings, and in December, published their findings. It was the largest single-species wildlife die-off ever documented. She says the discovery felt like a gut punch.
RENNER: I think as a scientist, really one of the most striking pieces was how swift the loss was. What that implies - the catastrophe that can happen in our changing world.
STUART-RASI: The culprit - climate change. Researchers concluded that a 2014 heatwave in the waters of the north Pacific Ocean, known as The Blob, disrupted the common murre's food web. It created a catastrophic rippling effect, causing 4 million common murres to starve to death within just a couple of years. Scientists expect heatwaves like The Blob to happen again in the future, meaning more birds could be in danger. If that happens again, bird watchers like Megan Dean and her young daughter will probably notice.
DEAN: Hey, Mo (ph), do you want to see if there's any birds in all this trash down here?
STUART-RASI: Now, Unalaskans are keeping an eye out for the common raven, a bird that has been missing here the past couple of years.
For NPR News, I'm Sofia Stuart-Rasi in Unalaska, Alaska. Transcript provided by NPR, Copyright NPR.
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