Mass death of seabirds in Western U.S. is ‘unprecedented’ – unexplained changes within ocean to blame
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May 2015 – OCEAN HEALTH – In the storm debris littering a Washington State shoreline, Bonnie Wood saw something grisly: the mangled bodies of dozens of scraggly young seabirds. In the storm debris littering a Washington State shoreline, Bonnie Wood saw something grisly: the mangled bodies of dozens of scraggly young seabirds. Walking half a mile along the beach at Twin Harbors State Park on Wednesday, Wood spotted more than 130 carcasses of juvenile Cassin’s auklets—the blue-footed, palm-size victims of what is becoming one of the largest mass die-offs of seabirds ever recorded. “It was so distressing,” recalled Wood, a volunteer who patrols Pacific Northwest beaches looking for dead or stranded birds. “They were just everywhere. Every ten yards we’d find another ten bodies of these sweet little things.”
Cassin’s auklets are tiny diving seabirds that look like puffballs. They feed on animal plankton and build their nests by burrowing in the dirt on offshore islands. Their total population, from the Baja Peninsula to Alaska’s Aleutian Islands, is estimated at somewhere between 1 million and 3.5 million. 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.” Although there doesn’t appear to be a link to the virus that killed tens of millions of sea stars along the same shores from California to Alaska over the past 18 months, some scientists suspect a factor in both cases may be uncharacteristically warm waters. The U.S. Geological Survey and others have performed animal autopsies, called necropsies, on several of the emaciated Cassin’s auklets.
They’ve found no evidence of disease or trauma—no viruses or bacteria, no feathers coated with spilled oil. The birds appear simply to have starved to death. “There’s very little evidence of food in their GI [gastrointestinal] tracts or stomachs,” said Anne Ballmann, with USGS’s National Wildlife Health Center. At first scientists weren’t too surprised by the carcasses washing ashore. When young auklets fledge in late summer, they all enter the water at the same time and start competing for food—shrimp-like krill and tiny crustaceans called copepods. For various reasons, last summer’s birth class of Cassin’s auklets was gigantic. Researchers expected a higher death toll, too. But they now are perplexed by the sheer numbers of dead birds and the spreading geographic extent of the die-off. “Death at this level and over this much real estate has to be from more than just that,” Parrish said.
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.” –National Geographic (January 2015)
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