Other marine wildlife deaths, including a handful of cassin's auklets (another diving seabird) and sea otters, have been reported as far south as Monterey Bay and as far north as Sonoma County.

On Monday, Ed Ueber, manager of the Gulf of the Farallones National Marin Sanctuary, said researchers have various theories about the deaths but can't say for sure what is causing them.

Ueber said such bird and otter deaths are seasonal but are higher this year than last. However, he added, "We don't believe it's super-high." The otter deaths, he added, are "within the realm of normal fluctuations -- given the data we have to date."

The seabird deaths may be attributable, he said, to "red tides [of plankton called dinoflagellates], [weak] upwelling [cold, nutrient-rich deep waters surfacing], or lack of food...

"[It may be] the water's too warm for food to come to the surface where the birds like to feed," Ueber explained.

However, he said, red tides have virtually been ruled out as a cause of the deaths. "Dinoflagolates usually don't affect birds, and we haven't found any of that in [dead] birds sent to the State Department of Health."

As for the sea otter deaths, Ueber said experts this past week told a meeting of marine sanctuary advisors, "They don't know anything [about the recent deaths]."

However, he added, Jan Roletto, research coordinator for the Gulf of the Farallones National Marine Sanctuary, "thinks it may be a brain parasite."

Parasites, he noted, were blamed for other otter deaths previously this year.

Ueber said that while all the recent dead seabirds found have been common murres, initially cassin's auklets and other dead birds were found.

Some emaciated murres found on West Marin beaches have been taken to the California Center for Wildlife in San Rafael.

As of Monday, the center was caring for 40 birds and six more were soon to arrive from San Francisco. Nor did the center expect the problem to end quickly.

"This is just the tip of the iceberg," said Wayne Wechsler, executive director of the center. Although treatment is labor intensive since all the birds must be fed with a hand-held tube hourly, volunteers "are making very nice progress," Wechsler said."