[obol] News: SF Chronicle: Dead murres, auklets washing ashore with little in their stomachs

[Andrew Orahoske]

Although seabird mortality is a common occurrence, as some OBOLers have 
noted, biologists at Point Reyes Bird Observatory and University of 
Washington are pointing to the affects of global warming on plankton 
abundance as a plausible culprit for the increased mortality figures.

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/04/03/BAGJEP0J8Q1.DTL

*Struggling seabirds*

*Dead murres, auklets washing ashore with little in their stomachs*

Glen Martin, Chronicle Environment Writer 
<mailto:glenmartin at sfchronicle.com>

Tuesday, April 3, 2007

West Coast seabirds are dying, apparently from a lack of food -- and 
some researchers think the phenomenon may be linked to global climate 
change.

This is the third year that scientists have found unusually large 
numbers of marine birds -- mainly common murres, but also rhinoceros 
auklets and tufted puffins -- washed up on beaches in California, Oregon 
and Washington. In 2005, the first year of the phenomenon, large numbers 
of Cassin's auklets also died.

Hannah Nevins, the coordinator for Moss Landing Marine Laboratories 
beach survey program, said 253 dead murres were recovered on 11 Monterey 
Bay beaches during the first week of March. During the past nine years, 
an average of nine dead birds were collected on the same beaches during 
the same week, she said.

About 180,000 breeding murres live along the West Coast, so it is 
unlikely the recent spate of deaths is enough to drastically harm the 
overall population.

"But if this continues for multiple years, then we could have real 
problems," Nevins said.

Most of the casualties were young birds that had just gone through their 
first winter.

"They were all in poor condition, and generally had empty stomachs," she 
said. "Either they were not finding food, or they were unable to capture 
the food they did find."

Bill Sydeman, the director of marine ecology at PRBO Conservation 
Science, a Bay Area group that specializes in avian research, said the 
deaths are worrisome because it now appears they are not isolated 
events. In the two past years, the winter deaths were followed by less 
successful breeding at the Farallon Islands, one of the West Coast's 
most productive seabird rookeries, he said.

"I would not be surprised to see the same thing this year," Sydeman said.

Sydeman said the trend appears to be linked to changes in the California 
Current -- a vast oceanic stream that delivers cold, nutrient-rich water 
from the Gulf of Alaska to the continental West Coast. Plankton thrives 
in this water, forming the basis of a food web that sustains everything 
from small fish to whales.

Fluctuations in the current in recent years appear to have resulted in 
regions of warmer water that support less plankton, Sydeman said. That 
can also reduce upwelling, a seasonal phenomenon that results in the 
replacement of warmer water along the Pacific Coast with cold, 
nutrient-laden offshore water.

Yet Howard Freeland, a research scientist with the Institute of Ocean 
Sciences in Sidney, British Columbia, said the California Current 
generally has remained strong during the past two years, though he said 
there have been some fluctuations.

But Julia Parrish, an associate professor in the school of aquatic and 
fisheries science at the University of Washington, said the North 
Pacific Ocean appears to be in major flux. During the past two years, 
she said, offshore upwelling did not begin off the continental Pacific 
Coast until summer, two months later than usual.

That was bad news for the birds because the warm water provided them 
little food during the height of the breeding season, Parrish said.

The once generally predictable North Pacific currents, she said, are 
"swinging like a pendulum." For example, in summer 2006, an unexpected 
"super upwelling" happened off the Oregon coast, sucking in vast 
quantities of abyssal water that was so low in oxygen that a temporary 
dead zone formed along the coast.

In typical years, said Parrish, very few horned puffins -- a bird that 
breeds in Alaska and winters offshore as far south as California -- are 
found dead on West Coast beaches.

"But during the last three years, we have found tens of them each 
season," she said. "That may not seem like a lot, but it is very 
significant, considering past statistics. More of them may be dying, or 
the currents may be shifting so that more are washed up on the beach 
instead of sinking. We don't know - but we do know things are changing, 
and that there are casualties."

Sydeman said the anomalies could be linked to global climate change.

"What's clear is that during the past decade, there's much more 
variability out there than there was during the preceding 40 years," he 
said.

"That probably causes some disability in the ecosystem to recover from 
human-caused impacts such as pollution, coastal development and 
fishing," he said.

------------------------------------------------------------------------

Affected populations

For the third year in a row, large numbers of seabirds are dying off the 
California coast -- probably due to starvation. Scientists think 
fluctuating currents in the North Pacific are delaying or weakening the 
influx of cold, nutrient-rich water to the coastal areas of the western 
continental United States, resulting in less zooplankton and fewer small 
fish, the staple of marine birds.

Common murre: Duck-size, penguin-like birds that nest on rocky ledges 
along the California coast. They consume small fish and krill, and have 
suffered from population declines even before the recent die-offs.

Cassin's auklet: A small seabird that feeds heavily on krill and nests 
in burrows or crevices. They breed from Alaska to Baja, including the 
Farallones. Although these birds had a large die-off in 2005, scientists 
are also worried about them this year.

Rhinoceros auklet: Larger than the Cassin's auklet and smaller than the 
common murre, this bird is distinctive for a small "horn" on its bill. 
It eats krill and small fish and breeds largely in Alaska and northern 
British Columbia, though some are found year-round in Washington, Oregon 
and California.

Horned puffin: A distinctively marked bird that generally stays out to 
sea, the horned puffin subsists on small fish. Dead puffins seldom wash 
up on beaches; recent discoveries of horned puffin carcasses in Oregon 
have led to worries that mortality for the species may be increasing.

 

 



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