>From th <<...OLE_Obj...>> e Anchorage Daily News, July 13, 2003
Plague of rats
One-pound rodents killing seabirds by the thousands
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By DOUG O'HARRA
Anchorage Daily News
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(Published: July 13, 2003)

A scrabbling horde of Norway rats has invaded one of the Northern
Hemisphere's most spectacular seabird colonies, consuming the brains and
eyeballs from countless auklets nesting at the base of a volcano on Kiska
Island, near the tip of the Aleutian Chain.
Scientists visiting the site during the past three summers have found
windrows of bird skulls, rat dens jammed with rotting auklet carcasses and
many empty bird-nesting crannies in the jumbled lava overlooking the Bering
Sea.
"The rats will just go from one nest to the next -- thousands and thousands
and thousands of adults and chicks getting their brains and eyeballs eaten
from their heads," seabird ecologist Ian Jones said. "It's a really horrible
show. There's no other way to describe it."
If left unchecked, the rats could cause ecological damage on the scale of a
major oil spill. Federal scientists are now trying to figure out whether the
rats can be eliminated with poison, though Kiska would be the largest island
where that has been tried. It may be the only way to save one of the
Pacific's natural wonders.
Each summer, 3 million to 6 million least and crested auklets and other
birds return to Sirius Point in flocks that block the sky like smoke and
fill the air with trilling cries. Scientists call the scene "staggering," a
spectacle of "biblical proportions."
But a study in its third year has found adults dying or abandoning nests,
leaving chicks to starve or get mangled. Last year, surveys found that only
one-tenth of least auklet eggs hatched chicks that flew away -- the lowest
reproductive success ever observed for the species, which forms 80 percent
of the colony.
"What we suspect at this point is this colony could well be gone in 20 years
or so," said federal biologist Art Sowls, with the Alaska Maritime National
Wildlife Refuge. "It is kind of a horror movie scene."
WORLDWIDE RAT PLAGUE
The dramatic spread of rats on Kiska is one more crisis in a worldwide rat
plague that threatens other important nesting sites in Alaska. Carried on
ships and aircraft, dumped by cargo and shipwreck, rats have reached more
than 80 percent of the world's islands and driven hundreds of species to
local extinction.
One way or another, rats have made it to at least 21 large Alaska islands,
not counting islets.
They got to Kiska, part of the Rat Islands group, during World War II and
gradually overran much of its rugged 70,000 acres. But it was only during
the past decade that scientists realized the full extent of the danger to
the auklets, which live in the crumbling lava only a few months a year.
"It is an enormous disaster," said Jones, an Iowa-born associate professor
of biology at the Memorial University of Newfoundland, who has done field
work in Alaska for the past 18 summers. "The number of seabirds that are
being killed by rats each year (on Kiska) are more than what were killed by
the Exxon Valdez oil spill."
An ambitious experiment to poison rats at Sirius Point late this winter or
next is now under development, said Peter Dunlevy, a refuge biologist who
specializes in fighting introduced, or alien, species. Biologists may put
out a government-approved bait called Ramik Green, which contains an
anti-coagulant that causes the rats to die of internal bleeding.
The goal would be to establish a sort of rat-free beachhead in the talus,
said Vernon Byrd, the refuge's supervising biologist. "We're not 100 percent
sure if we can effectively control them. We think we can, but we don't know
for sure."
If the rats get knocked back at Sirius Point in 2004 or 2005, the refuge
would then try to get permission to broadcast the bait from aircraft to
eradicate rats from the whole island, Byrd said. An environmental assessment
would have to be done first.
This work on Kiska is part of a broader campaign to drive rats from other
refuge holdings, like Rat Island, and keep them from invading bird colonies
on St. Paul, Buldir and other islands.
Scientists have used poison to remove rats from islands off New Zealand and
British Columbia. The biggest island where it has worked is 27,900-acre
Campbell Island, about 440 miles south of New Zealand. Kiska is more than
twice as large.
"You have to kill every single rat," Dunlevy said. "You can't just go to the
hot spot."
It wouldn't be cheap either.
It cost $1.5 million for helicopters to spread 132 tons of bait on Campbell
in 2001, an effort that killed an estimated 200,000 rats over 10 days. Teams
have returned each year to check, and the island was just recently declared
rat-free.
The timing on Kiska will be critical, Jones said, because the rats won't
touch anything but auklets once the birds arrive in late spring. Leave a
single breeding pair alive and the rats would soon rebound.
"What's going on right now is the massive kill-off of birds, but the
insidious thing about the rats is they can survive through the winter on
next to nothing," he said. "When we arrive in the spring, we find evidence
that the rats have been eating each other."
CENTURIES-OLD PROBLEM
For centuries, people have been spreading alien species across the globe, by
accident and by design, through ballast water and cargo and ships and
agriculture.
Once invasive animals and plants establish themselves in new habitats
without their natural enemies, they can multiply with catastrophic effect,
altering the local ecology, driving out other species and causing billions
of dollars in damage.
Like most other Aleutian islands, Kiska had no indigenous land mammals.
Trappers released arctic foxes on Kiska Island in 1835, part of widespread
fox farming on hundreds of Alaska islands. Then came the Norway rats, when
the island was occupied by Japanese and Allied forces.
In 1986, the U.S. Fish and Wildlife Service eradicated foxes from Kiska as
part of a campaign to save Aleutian Canada geese from extinction throughout
the refuge. About 49,000 beef tallow baits laced with the poison 1080 were
dropped on the island, killing an estimated 700 foxes, according to a
federal report.
But biologists visiting the island in spring 1987 found that Norway rats had
exploded in number with the foxes gone, The Associated Press reported that
spring. A federal report noted the apparent surge in rats as evidence that
the foxes had been eliminated.
Biologists no longer think removing the foxes helped the rats, Byrd said.
After further studies, and consultation with rat experts from Canada, they
now believe rats were just foraging more openly on the beaches with the
foxes gone.
There's little overlap between foxes and rats, Dunlevy said. "Rats are
almost always nocturnal, and foxes hunt during the day. There was just too
many" rats.
No one knows when the rats reached Sirius Point from the island's harbor
area, but it might have taken decades, Byrd said.
One of Alaska's most common seabirds, auklets spend most of their lives on
the ocean, subsisting on tiny crustaceans called copepods. They only come
ashore to nest in rock crevices of a certain size, seeking protection from
predators during the four weeks before hatchlings can fly. A 1960s volcanic
eruption created a new lava dome at Sirius Point saturated with great auklet
nesting sites, Jones said, probably expanding the colony.
"It's just a maze under there of tunnels and crevices and cracks, with
auklets sitting on their eggs in the cracks," Byrd said. "It's easy for the
rats to sneak up on them."
Biologists knew that the 1-pound rats were snapping the necks of the 3-ounce
least auklets and eating them. But they did not believe the rats could
threaten the overall auklet population during the few weeks the birds were
present, Byrd said.
Even if thousands of rats gorged on auklets during the two-month nesting
season, they would hardly dent a population that numbered in the millions.
"I thought there were so many, and I thought they were only available to the
rats for only a short period," Byrd said. "Clearly, I was wrong. Now it's
very, very likely that those rats are going drive them to extinction."
What changed everything was the discovery in the early 1990s that rats were
caching adult birds in underground burrows, where they often rotted away
uneaten. Jones later found one stash with 148 decomposed birds near a steam
vent.
"That changed our perception," Byrd said. "That upped the ante."
Sowls, Jones and other biologists spent several weeks at Sirius Point in
2000, and Jones began a detailed three-year study in 2001 to document the
effect of rats on auklets.
"We found scenes of utter devastation," Jones said. "We found thousands of
predated carcasses of birds. We found thousands of eggs, and we found
windrows of thousands of skulls -- that's the only way to put it.
"Each of these skulls had a little hole removed, right in the back of the
skull, where the rats had chewed through to eat the brain."
Another worry: What if auklets have been coming to Sirius Point from other
islands, attracted by new nesting habitat in the lava?
"It could be like it's a giant black hole that's sucking in auklets from
other islands," Jones said. "It's almost like a hotel where guests are
checking in and disappearing, and there's always a vacancy sign out front."
RATS CRAWLING EVERYWHERE
After the biologists get dropped off in June, they spend 12-hour days
crawling around in the crumbling lava laced with holes. The team surveys
auklet nests, counts chicks and adults, traps rats and takes tissue samples
to find out what they're eating.
The weather is often horrendous, forcing the biologists to hunker down in
their storm-proof tents. Water must be collected with blue tarps, and the
only bathing can be found in a hot pool accessible at low tide in good
weather. The team checks in by radio twice a day to the refuge office on
Adak, a 24-hour boat ride to the east.
"We're working all the time, so we don't have time to go crazy," said Jones,
43.
This summer, Jones returned to the island with graduate student Heather
Major and two field assistants, Jacques Marqis and Travis Clarke. During
previous seasons, Jones said they found rats crawling everywhere -- on the
beaches, through the holes in the lava. Unbaited snap traps would catch
them. They were unafraid, but had no interest in raiding camp supplies when
surrounded by auklets.
"I can't get mad at the rats," Jones said. "I've had them in my hand, and
it's a beautiful animal. But they're terrible killers and they don't belong
there."