From National Geographic:
Last year, beginning about Halloween, thousands of juvenile auklets started washing ashore dead from California's Farallon Islands to Haida Gwaii (also known as the Queen Charlotte Islands) off central British Columbia. Since then the deaths haven't stopped. Researchers are wondering if the die-off might spread to other birds or even fish.
"This is just massive, massive, unprecedented," said Julia Parrish, a University of Washington seabird ecologist who oversees the Coastal Observation and Seabird Survey Team (COASST), a program that has tracked West Coast seabird deaths for almost 20 years. "We may be talking about 50,000 to 100,000 deaths. So far."
By comparison, not one of the five largest U.S. bird mortality events tracked by USGS since 1980 is estimated to have topped 11,000 deaths. In Europe, according to the U.K.-based Royal Society for the Protection of Birds, the worst die-off on record occurred in 1983, when 57,000 guillemots, razorbills, puffins, and other seabirds perished in the North Sea and washed up on the British coast.
"You get some of this with seabirds every year," said David Nuzum, with the Oregon Department of Fish and Wildlife. "You get so many juveniles out there, and they've got this steep learning curve for feeding after being separated from their parents, so you always get a die-off in winter. But I've never seen anything like this, ever, and I've been here since 1985."