A group of common murres on a cliff edge in Alaska Maritime National Wildlife Refuge. Largest Seabird Die-off in Modern HistoryBetween 2015 and 2016, approximately 4 million common murres (Uria aalge) disappeared from breeding sites across Alaska. The cause was linked to a sustained marine heatwave in the North Pacific, a phenomenon scientists labeled “The Blob”. Comparison of common murre colony on a census plot, South Island, Semidi Islands, Alaska Maritime National Wildlife Refuge, before and after the 2015-2016 marine heatwave. The seabird die-off dwarfed previous ecological disasters by scale.