In Unalaska, citizen scientists help document largest single-species wildlife die-off ever recorded

It was a chilly, gray December morning on Front Beach in Unalaska and Megan Dean gripped her binoculars, counting birds in Iliuliuk Bay.

“One, two, three, four,” Dean counted methodically, watching them bob in the waves and making sure to track them before the birds dove underwater. “Ten more black scoters. I have a couple of cormorants.”

Dean was part of Unalaska’s Christmas Bird Count, a winter tradition now in its 32nd year. Eighteen people spent the morning of Dec. 14 outside tallying every bird they could find. It was part of the Audubon Society’s nationwide count that helps scientists track changes in bird populations.

“It’s good just to get out in the winter and have a greater purpose, a good citizen science project to get you through the dark days,” Dean said.

The largest bird populations in Unalaska’s 2024 Christmas count were black scoters, harlequin ducks, glaucous-winged gulls and bald eagles. But a notable bird was missing: the common murre. A new study said its absence represented a catastrophic rippling effect in Alaska’s waters.

Not a single common murre was spotted in Unalaska’s Christmas bird count. In 2009, locals counted more than 4,000 of them. In 2014, a catastrophic marine heatwave struck and their numbers started plummeting. Scientists linked the heatwave to human-caused climate change.

Suzi Golodoff, who compiled Unalaska’s annual Christmas bird count and had spent nearly 50 years observing the island’s birds as a naturalist, said the decline was unprecedented.

“Sometimes you see small populations of birds, they become more and more vulnerable and they become extinct. But when a bird like a murre is hit, I mean, you know, something’s really haywire in the big picture,” she said.

Golodoff said these birds played a crucial role in Alaska’s marine ecosystem. Large populations of the common murre helped recycle nutrients throughout the ocean. They feed on small fish and nest in colonies with thousands of seabirds packed together on narrow cliff ledges. In those numbers, their calls create a wall of sound.

Golodoff takes out her phone.

Alaska used to be home to a quarter of the species’ world population – 8 million common murres.

Scientists in the new study said the heatwave, also known as “the blob,” disrupted their food web in the North Pacific Ocean. Four million common murres starved to death in the largest single-species wildlife die-off ever documented.

Heather Renner, the study’s lead scientist, said the discovery felt like a gut punch.

“We can’t stop heat waves without mitigating climate change, but I think there’s lots of things we can do to protect vulnerable species, and I think the urgency of them becomes a lot more relevant,” she said.

The murre die-off might have gone unexplained if it weren’t for decades of observations from researchers and citizen scientists. Renner said they pieced together what happened using 50 years of data — including records from coastal regional citizen scientists who had been documenting dead birds washing up on beaches for decades.

Back in Unalaska, citizen scientists were documenting another change in the bird population. The area used to have hundreds of common ravens, but for the past couple of years their population had dropped to single digits. Their 2024 Christmas Bird Count found only three ravens, down from their usual 200.

It’s another stark decline. Locals say common ravens used to be a constant presence, known for stealing from pickup trucks and hanging around dumpsters.

Dean didn’t spot any ravens during her count. Four years ago, she would have expected about 20.

“I mean, we just passed by a bunch of people’s houses. We passed by a demo location that’s got fresh, new stuff being dug up, shiny things. And I don’t know if I was a raven, I’d be all over that,” she said.

It was too soon to say why the raven count had declined so sharply. Scientists didn’t think the 2014 marine heatwave was the cause, but they weren’t ruling it out.

Unalaskans suspected another consequence of human-caused climate change: highly pathogenic avian flu. A study indicated the bird flu would likely adapt and spread, potentially in unprecedented ways.

For now, the counting continues.