A Decade After Massive Pacific Heatwave, Scientists Confirm It Produced The Biggest Bird Kill On Record

When Heather Renner and her colleagues began noticing thousands of common murres washing up on Alaskan beaches nearly a decade ago, they knew something was terribly wrong. It would take years of study to confirm they had witnessed the largest die-off of any bird species ever recorded in the modern era, according to new research published in the journal Science on Thursday.

Back then, the waters of the northern Pacific Ocean where these sleek seabirds spend much of their time were unusually warm, the start of what would become the largest marine heat wave on record. The murres that made landfall were emaciated, showing they had starved to death. The scientists knew then that the die-off was one of the most visible and extreme examples of how climate anomalies in the warming world can throw wildlife populations into turmoil.

But after seven years of monitoring common murre populations across 13 nesting colonies in Alaska, Renner and her colleagues at the U.S. Fish and Wildlife Service now realize they hadn’t fully grasped the scale of what was happening to those birds. “It was just way worse than we thought,” said Renner, the supervisory wildlife biologist at the Alaska Maritime National Wildlife Refuge. The research by Renner and her colleagues found that more than half of Alaska’s common murres died — some 4 million birds — in what they described as the largest mortality event of any non-fish vertebrate wildlife species reported during the modern era. The killing was an order of magnitude larger, she said, than the hundreds of thousands of murres that perished in the 1989 Exxon Valdez oil spill in Alaska.

“We’ve had lots of long-term declines that have been observed in wildlife,” she said. “But what’s really different here — that we haven’t seen before — is this really swift catastrophe where in one year we have half the population of this really abundant seabird just wiped out.” Before the two-year marine heat wave that ended in 2016, Alaska had an estimated 8 million common murres — a quarter of the world’s population — spread across abundant colonies in the Gulf of Alaska and the Eastern Bering Sea. These black-and-white seabirds nest in dense clusters among shoreline cliffs during the summer months and then head to the ocean the rest of the year to feast on schools of small fish such as capelin and sand lance, herring and krill.

EDIT

https://www.washingtonpost.com/climate-environment/2024/12/12/common-murre-alaska-climate-change/