Scientists fear unusual weather behind massive seabird die-off
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Monday, January 30, 2006
Scientists fear unusual weather behind massive seabird die-off
By ROBERT McCLURE
SEATTLE POST-INTELLIGENCER REPORTER
Alone in the nest, the starving seabird chick looked a little woozy. Then
it collapsed.
Hours passed before the desperate mother bird returned, a fish tail
sticking out of her beak. Again and again she offered the fresh morsel.
But it was too late -- the baby bird was dying.
"It's an ugly, gut-wrenching thing to watch," said University of
Washington researcher Julia Parrish, who witnessed such a scene repeatedly
last summer, hidden amid the cacophony of 6,000 nesting murres on Tatoosh
Island off the Olympic Peninsula.
Upwelling
The murres' unusual mass starvation became a clue in a mystery unfolding
along the West Coast.
Weather, scientists know, is the key to the puzzle. For some reason, winds
and currents crucial to the marine food web just didn't happen on schedule
last year.
Seabird breeding failures in the summer were preceded by tens of thousands
of birds washing up dead on beaches in Washington, Oregon and California.
And Washington's largest colony of glaucous-winged gulls also sputtered:
Where 8,000 chicks normally fledge, 88 did last year.
"The whole process broke down," Parrish said. "We don't know what
happened."
Earlier this month, 45 researchers met in Seattle to hash out the cause.
Though they couldn't trace the source of the weird weather, many are
warily eyeing the coming spring, wondering: Was that just a blip, an
anomaly -- or is this what global warming looks like?
Recall that at this time last year, Seattleites were cooing about a string
of sunny winter days -- if they weren't complaining about the lack of
powder on the slopes at Snoqualmie. It was warm and dry. It marked the
third year of above-normal ocean temperatures.
Then rain started pouring in early spring. At a time when the birds should
have been making and feeding babies, a network of beachcombing
citizen-scientists run by Parrish instead found them dead.
"It was the birds that were the first harbingers of this whole problem,"
said Bill Peterson of the National Oceanic and Atmospheric Administration,
which set up the Seattle meeting.
The dramatic downturns among certain bird species didn't happen in a
vacuum.
Researchers last year also recorded low catches of juvenile salmon and
rockfish, and there were sightings of emaciated gray whales. Those
findings were preceded by the first-time appearance in Washington of
thousands of squid normally not found north of San Francisco. And a kind
of plankton typically found near San Diego bloomed along Northwest beaches.
A scientist studying the longest-running set of indicators of Pacific
Ocean conditions says we can expect this kind of thing to repeat as the
planet warms and weather patterns are altered.
"There are all these unconnected reports of biological failures," said
John McGowan of the Scripps Institution of Oceanography in La Jolla,
Calif. "It's all the way up and down the coast. ... There's a lot of
evidence there are important changes going on in the Pacific coast system."
'The smoking gun'
By the door to Parrish's office is a little sign: "I really need to stop
depending on birds for important information. They're cute to look at but
don't have much upstairs."
From her perch above a courtyard at UW's College of Ocean and Fishery
Sciences in Seattle, Parrish directs the Coastal Observation and Seabird
Survey Team. About 300 volunteers scour Oregon and Washington beaches for
dead birds.
Based on monthly surveys, researchers estimated the dead birds numbered in
the tens of thousands. Dominating the toll were the Brandt's cormorant and
the common murre.
"They were clearly starving to death -- no fat, reduced musculature,"
Parrish said. "The smoking gun is no food."
Unlike migratory birds, they were stuck with what the Northwest coast had
to offer. Unlike birds with wider-ranging diets, such as gulls, both rely
almost exclusively on diving deep underwater for small schooling baitfish
that also feed whales, seals, salmon and other animals.
At Tatoosh Island, it looked like the same story. The murres like fatty,
nutritious sand lance, herring, surf smelt and eulachon -- the latter
nicknamed "candlefish" because they're so full of oil that, when dried,
they can be placed upright and lit to burn like a candle.
For a murre, eating those fish "is like popping little energy bars,"
Parrish said.
But last summer the murres brought back no sand lance and hardly any
herring. Catches of the other two fish also were reduced. Instead
Parrish's research team saw them toting fish like the Pacific saury, which
they had almost never seen the birds eating in 14 years of watching them.
"The steak and chicken fell out of the diet," Parrish said. "It's like
going to the grocery store and (seeing) there are only a few yucky things
in the store. You adapt by using what's there."
The phenomenon was widespread. At Triangle Island in British Columbia and
California's Farallon Islands, researchers saw a third seabird, the
Cassin's auklet, show signs of starvation, said Bill Sydeman of the Point
Reyes Bird Observatory.
The Farallon auklets started the breeding season late. Only half as many
as normal even tried. Then they abandoned the nests.
"That's unprecedented in 35 years of studying Cassin's auklets on the
Farallons" and unnoted in decades of anecdotal accounts before, Sydeman
said.
In nearby waters, researchers found a 60 percent reduction from the last
year in the birds' primary food, a tiny shrimplike crustacean called
krill. Up in British Columbia, the birds eat a different form of plankton
-- yet also had trouble raising young.
No one thinks a single year's breeding failure is a catastrophe for
overall populations of the birds. They live many years.
But it was unusual and widespread enough to spark urgent questions.
"It's something having to do with food," Sydeman said. "We're all pretty
sure."
Weather sparks meeting
Along the coast of Washington and Oregon, researchers think they know what
happened: The wind didn't blow.
Usually in the spring, a weather maker called the Aleutian Low that throws
winter storms our way moves north. Soon strong winds blow from north to
south. Because the Earth is turning to the east, these winds push the
surface of the Pacific to the southwest, leaving a little gap in the water
near shore.
Water from deep in the ocean surges up to fill the gap. It's cold water,
loaded with nutrients from dead plankton, dead fish, fish excrement and
more.
"Basically, you can think of it as a lot of schmutz that settles to the
bottom," Parrish said.
The cold water is fertilizer to the ocean garden. No cold water, no
plankton. No plankton, no sand lance or other "forage fish" -- staples of
many fish and birds.
Last year, though, the winds from the north didn't start in March or April
as they normally do. Nary a wisp came until late May, and it didn't really
get going good until mid-July.
The scientists' meeting in Seattle was organized to bring together
oceanographers, atmospheric scientists, marine mammal experts, seabird
biologists and researchers who model ecosystems and ocean circulation.
"The weather guys didn't really know what to say other than it was weird
weather. That's not very satisfying," said Peterson, the oceanographer.
The term "global warming" oversimplifies a chain of coming changes -- some
related to warming, some not, but happening simultaneously, scientists
emphasize. Climate change is superimposed on natural cycles.
"We're all scientists. ... We want to know why, and if it could happen
again," Peterson said.
Instead, they will write a series of scientific papers carefully
documenting their observations.
A look at the past, said Scripps' McGowan, is telling: In the last 30
years, the top 300 feet of the Pacific warmed and became more dense.
Off Southern California, zooplankton are down 70 percent, fish larvae 50
percent, and there have been massive die-offs of kelp. McGowan's
institution has studied ocean temperatures since 1919 and started a
comprehensive Pacific monitoring project in 1949.
In Puget Sound, the number of seabirds dropped by nearly half since the
1970s. Nearly a third of seabird species are legally protected or
candidates for protection.
"All kinds of things are changing, and the biology is responding in funny,
non-linear, confusing ways," McGowan said. "Not everything has declined,
but many things have."
Gulls abandon nests
The largest gathering of nesting seabirds in Washington happens every
summer at Protection Island, between Sequim and Port Townsend off the
northeast Olympic Peninsula. It's also the state's largest colony of
glaucous-winged gulls.
There, researcher Joe Galusha of Walla Walla College has studied the gulls
for 25 years. Last year the birds began gathering as usual. About 8,000
paired up, established nests and laid eggs -- just as always.
The gulls seemed to have no trouble gathering food -- unlike the murres at
Tatoosh Island.
The gulls have a much less specialized diet than the murres, which may
explain the difference, Parrish said.
Even so, most of the gulls later abandoned their nests.
Galusha thinks bald eagles may be to blame. When he started watching the
gulls in 1980, the eagles' numbers were way down. Perhaps seven or eight
harassed the 8,000 or so gulls by the early 1990s.
Their numbers grew gradually to the point that last summer, up to 38
different eagles menaced the gulls simultaneously.
Every time, the gulls had to take flight -- which burns energy. Most
simply gave up.
In the end, 88 chicks were fledged where 8,000 to 10,000 normally are.
"We classify that as catastrophic reproductive failure," Galusha said.
Simple, right? Maybe not. Galusha and others still want to know why eagles
are increasingly turning to Protection Island. Is their food supply also
in flux?
"Next summer is key," Galusha said. "This may simply have been an
aberration."
The Sea Doc Society, a University of California-Davis research arm, is
about to fund a study by Parrish to investigate seabird diets in the Puget
Sound region.
Nathan Mantua, a UW scientist studying the effects of climate change on
the Northwest, said he will run climate simulations to see how often this
kind of thing could have been expected in the past and how often we might
expect it as man-made greenhouse gases alter the climate.
"We don't know if it's just a random thing or something we might expect to
see more or less of in the future," Mantua said. "If you're thinking this
is just an unlucky roll of the dice, how often will it happen again?"
WEIRD WEATHER
With ocean temperatures warming to unusually high levels over the last
three years, scientists noted a string of unusual happenings affecting
marine life from northern California to Alaska.
Map
1. Triangle Island: Nesting success plummeted for the Cassin's auklet,
a seabird, in 2005.
2. Lake Washington and Ship Canal: About half the 2004 run of sockeye
salmon -- some 200,000 fish -- failed to materialize. Scientists suspect
overly warm water was the cause.
3. Whidbey Island: A Humboldt squid, normally found in Mexico and
southern California, turned up on the beach on Jan. 2.
4. Protection Island: Last summer, glaucous-winged gulls that normally
fledge about 8,000 chicks produced only 88.
5. Tatoosh Island: Breeding started late for common murres last spring.
Only about one-fifth fledged chicks, compared to up to four-fifths in a
good year.
6. Northwest Coast: Tens of thousands of common murres and Brandt's
cormorants -- emaciated at a time of year they should be flush -- turned
up dead on Oregon and Washington beaches in spring 2005.
7. Southern Washington to Alaska Panhandle: Numerous sightings of
Humbolt squid, which normally lives off Southern California and farther
south, in summer 2004.
8. Northwest coast: Gray whales migrating from Mexico to the Bering Sea
had so exhausted their fat reserves that their bodies were misshapen as
they passed by last spring.
9. Northwest coast: Scientists trawling for young salmon found counts
extremely low in spring and fall 2005.
10. Northern California: Scientists trawling for young rock- fish found
counts very low in 2005.
11. Farallon Islands: Auklets that abandoned their nests in
unprecedented numbers. Where hundreds of chicks normally are produced,
only a handful were in 2005. Lack of food is blamed.
12. Monterey, Calif.: Large number of seabirds found dead on beaches in
spring 2005.
P-I reporter Robert McClure can be reached at 206-448-8092 or
robertmcclure seattlepi com |