In 2016, scientists became aware of a die-off of common murres, seabirds resembling flying penguins, that were found washed ashore from Alaska to California. A 2020 study estimated, based on an extrapolation from carcasses found on beaches, that roughly 1 million murres may have died, calling it “unprecedented and astonishing,” even “biblical.” However, a new study undertaken by some of the same researchers suggests the death toll may have been far greater. The research estimates that 4 million common murres (Uria aalge) died from 2014 to 2016 during the height of a marine heat wave nicknamed “the blob” in the north Pacific Ocean, with murre deaths seemingly peaking in early 2016. This makes it the largest mortality event not just among birds but of any non-fish vertebrate in the modern era, the researchers say. “I think what really punched us in the gut was having a really abundant, widespread top predator in the marine ecosystem that, over a really short period of about a year, lost half of its population,” study lead author Heather Renner, a supervisory wildlife biologist with the U.S. Fish and Wildlife Service, told Mongabay. To determine the scale of the loss, Renner and co-authors compared the common murre populations at 13 breeding colonies in Alaska for seven years before and after the heat wave. Until 2014, there were roughly 8 million murres in Alaska, about one-quarter of the world’s population. But during the heat wave between 2014 and 2016, there was a dramatic population drop-off of…This article was originally published on Mongabay
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