Location: Guam and the Northern Mariana
Islands in the West Pacific.
The tiny island of Guam, a 200 sq.mile outcrop
in the northwest Pacific, was once home to several species of endemic
flightless-birds, a native fruit bat species and also a thriving
population of geckoes and skinks. What Guam did not possess, nor
want, were snakes, but then one species arrived, accidentally introduced
in military equipment returning to the US from New Guinea and the
Solomon Islands following WWII. The snake concerned was a particularly
aggressive and voracious predator, the rear-fanged venomous Brown
treesnake, at equilibrium within its natural range but a menace
to the vulnerable fauna of these isolated islands. Brown treesnakes
are now thought to number over one million specimens on tiny Guam,
a ratio of six snakes per person. Within a very short time the treesnakes
created an ecological disaster. They pushed 10 species of native
birds into extinction, wiped out Guamese populations of Pacific
geckoes, and still threaten the remaining three species of native
Guam birds and the native fruit bat. Growing fat on a diet of cultivated
chickens and hens eggs the treesnake has also become the cause of
numerous power-outs as snakes enter electrical circuit boxes and
black-out entire towns. Even more worrying, large specimens have
taken to attacking and biting children. Although there have not
been any human fatalities due to attacks by these immigrant snakes,
there have been several serious accidents and the possibility remains
that a brown treesnake might kill a child. Mark sets out to investigate
the threat posed by the treesnake, a difficult job for someone more
used to promoting snakes positively. En route he discovers some
of the methods being used by the authorities, including the US Air
Force at Andersens Air Force Base, to eliminate and control
the spread of the brown treesnake problem. Mark also has to overcome
his own fear of heights in an attempt to find where the snakes lay
Other Pacific islands are very worried about the brown treesnake.
Mark visits the neighbouring snake-free island of Saipan to experience
what Guam was like before the arrival of the treesnake and also
to see what measures the Saipanese have developed to prevent their
own snake invasion.
The voracious and venomous Brown treesnake
(Boiga irregularis) is an unwelcome invader on an island inhabited
by flightless birds.
||Common house gecko
Location: Guam, Saipan and Tinian are the isolated protruding peaks
of a mountain range rising from the deepest ocean floor in the
Don Nichols, from the National Zoo, Washington, tells O'Shea how
he proposes to control invading treesnakes with a virus.
Rapelling down the 250ft Ritidian was one of the toughest things
OShea has ever done. Fortunately Kurt Wexel of Micronesia
Cavers was there to offer his support.
O'Shea with an handful of Brown treesnakes at the US Geological
Survey Treesnake Research Laboratory