Large-scale die-off of Cassin's auklets reported along US West Coast

© SABINE'S SUNBIRD

Cassins Auklet at night (Ptychoramphus aleuticus) photo taken in 2003 on Farallon Islands

Scientists up and down the West Coast are monitoring what appears to be a large-scale die-off of young Cassin's auklets, small seabirds whose breeding grounds include a colony in the Farallon Islands west of San Francisco.

Emaciated, white-bellied birds have been washing ashore in Sonoma County and along a broad swath of California coastline since early November after a period of ocean warming in the Farallones region and disappearance of the tiny krill that provide their main source of food, researchers say.

Scientists are still collecting data, but the largest concentration of dead birds appears to be in northern Oregon, according to monitors in the Pacific Northwest. Birds have been washing up in Washington, as well.

Scientists say anyone who finds a dead bird should leave it alone so that monitors surveying the beaches can collect accurate records on the die-off.

Just what's behind the phenomenon is far from clear, those involved in the research say.

One factor may in fact be the species' recent breeding success, which means a particularly large number of inexperienced fledglings were introduced last summer to the harsh challenges of life at sea, they said.

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