Dutch scientists said they are baffled after 20,000 dead or dying guillemots washed up on North Sea beaches in a phenomenon not seen for decades. The fish-eating seabirds have been washing up between the northern Wadden Islands and southwestern Zeeland — all showing symptoms of severe starvation, a marine biologist said. “What’s killing them though is the million-dollar question,” Mardik Leopold, a maritime researcher for Wageningen University, said. “And we still don’t know what the answer is. It’s an alarming situation,” he added. Scientists are planning a mass autopsy of hundreds of dead birds next week, hoping to shed more light on the mystery.