Seabirds in the northwest of US and Canada are dying in their thousands, but no-one knows why.
Scientists are trying to halt one of the worst recorded catastrophies in marine bird history.
Volunteers scour the shores of Washington state for dead birds-something they do every month. November was a bad month.
"We had almost 130 of them out on our beach within about a mile stretch, plus 10 other species. It was a long day," said Kathy Freitas, volunteer bird surveyor.
So far, volunteers have found around eight-thousand carcasses of the blue-footed seabird called the Cassin's Auklet along the coast from British Columbia down into northern California.
Scientists estimate as many as 100,000 auklets - most of them young - have died. The question is why .
Researchers believe that the Cassin's Auklets flew closer to the shore than they normally do during their annual migration south. When they could not find the amount of food they're used to, they ended up dying of starvation and washed up along shores of beaches like this.
"They're probably not finding food there, or enough food. And that's probably causing some of the population to come closer to shore. And they're not finding food there because they're dying and washing ashore," seabird ecologist Julia Parrish said.
Tests confirmed the auklets likely died of starvation. Scientists say they didn't find any traces of other potential killers like oil, viruses or bacteria. They now suspect warm water is to blame.
The birds feed on tiny shrimp-like creatures called krill, which grow in cold water. U.S. scientists say an expanse of "exceptionally warm water" has spread across the Pacific-from the Gulf of Alaska to Japan.
The auklet deaths are the latest in a series of marine life "mortality events" in the world's oceans. Fish, birds and sea urchins have been dying off in record numbers.
In January, U.S. scientists published a study blaming disease for just over a quarter of the mass die-offs. Human actions, like pollution, caused 19%-and climate-related events factored into another 25%.
"There is a seasonal cycle in the ocean. It's warmer at the end of summer, colder at the end of winter. And last winter, it didn't cool off as much as usual," said Nick Bond, Research Meteorologist.
Some U.S. scientists predict the auklet die-off could spread to other marine life after this year.