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In the dense tropical forest, a slither of movement
can just be made out in the glow of our head torches.
A snake is entwined in the undergrowth. It is about 1m long, mostly dull
brown but with a vivid yellow underbelly.
We are face to face with Guam's "nemesis": the brown tree snake. And the
forests here are dripping with them.
The US territory, in the western Pacific, is only 50km (30 miles) long
and 10km wide, but it is packed with two million snakes.
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This reptile arrived here only 60 years ago but has rapidly become one
of the most successful invasive species ever.
Unhealthy appetite
Wildlife biologist James Stanford, from the US Geological Survey, says:
"Our belief is that they came at the end of World War II.
"We've looked at their genetics and they are all extremely closely
related, and it appears they came from the Island of Manus in Papua New
Guinea."
He explains that military equipment used by the US in Papua New Guinea
while the war raged in the Pacific was eventually sent back to Guam to
be processed. A snake probably crept on to a ship or a plane destined
for the island.
"And from that handful, or maybe even one already impregnated female, we
now have a population that is unbelievable in scale," he says.
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The snakes, which are mildly venomous, have caused many problems. They
get everywhere, and people have even woken up with them in their beds.
The island's power system is regularly shorted out by snakes crawling on
the lines. It is so frequent the locals now call power cuts "brown
outs".
But the biggest impact has been on the wildlife - it has been decimated.
The forests here are eerily quiet. Now the only place where the Guam's
native birds, such as the koko, can be seen on the island are in cages
in a captive breeding centre.
"The brown tree snake has had a devastating impact. Ten out of 12 native
forest bird species disappeared in 30 years," says Cheryl Calaustro from
Guam's Department of Agriculture.
"The birds here evolved without predators. They were quite naive. And
when the snake arrived on Guam it ate eggs, juveniles, adults. Whole
generations disappeared."
Toxic mouse bombs
But the snakes did not stop there.
Dr Stanford explains: "We thought it would be limited: 'OK, if it wipes
out the birds, it will decline.' It wasn't the case. It just switched
what it was feeding on - rodents, lizards, small mammals - across the
board."
Now the locals are fighting back. And they are unleashing some unusual
weapons in their war against the snake.
(Which, by the way, why are skyscrapers allowed to include antennas in
their height? If reaching my hand upward counted in my height I'd be
playing center for the Knicks.) China leads the list with ten of the
towers in seven different cities — the tallest being the Ping An Finance
Center, in Shenzhen, at 2,165 feet (660 meters).
The tallest tower in the works is the Kingdom Tower in Jeddah, a city on
the western coast of Saudi Arabia. The tower will soar to 3,280 feet
(over 1,000 meters), making it more than 500 feet taller than the
world's current champion, the Burj Khalifa in Dubai. Built at a cost of
$1.2 billion, the completed Kingdom Tower will be a mixed-use facility
that includes a luxury hotel, luxury condominiums, and office space, in
addition to the world's highest observatory.
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One effort has involved air-dropping mice that have been laced with
poison and fitted with parachutes out of helicopters. It provides a
deadly dinner for any unsuspecting snakes below.
"Right now we are using acetaminophen (paracetamol). It commonly used as
a pain reliever and fever reducer in humans, but it is 100% lethal to
all brown tree snakes," explains Dan Vice of the US Department of
Agriculture.
"If they eat that dead mouse containing acetaminophen, they will die."
But this is a battle on two fronts. Not only is the US government trying
to clear the snakes, it is also trying to prevent the problem being
passed to anyone else.
And to do this, it has enlisted the help of some small dogs.
Snakes on a plane
In a busy cargo depot close to the airport, Elmo the Jack Russell,
kitted out in a smart, green uniform, is sniffing box upon box of goods
waiting for export.
He is on the hunt for any unwanted stowaways.
As he catches wind of an unusual scent, he begins to scrabble, alerting
the government inspector to the presence of a snake - and is rewarded
with a treat.
A small army of dogs check every single item of cargo before it leaves
Guam.
"It is a monumental project. We're working 24 hours a day, seven days a
week," says Mr Vice.
"Cargo doesn't stop, the airport doesn't shut down, so we have to be
there to make sure the cargo going on the airplane has indeed been snake
inspected."
Letting the snakes on a plane could have devastating consequences.
Mr Vice says: "Economics researchers have tried to apply the impact of
snakes to Hawaii. They found it could cost $400m or more if the snake
became established.
"The impacts are running across all kinds of parts of the economy. It
includes healthcare for humans because the snakes bite people, damage to
the power system, lost revenue associated with declines in tourism and
ecotourism."
However, with so many snakes on the island, controlling the problem is
an uphill battle.
And today, Guam serves as an example to the world of what happens when
an invasive species takes hold.
The worry is that it may be too late to clear the infestation, but Mr
Vice says this should not stop the islanders from trying.
"Our long-term goal is to eradicate the snake," he says.
"The problems here are so profound we don't want to let them go anywhere
else, and the only way to achieve that is to get rid of them
completely." |