A slithering menace

Brown tree snake wipes out 10 bird species in Guam

From Gary Strieker (CNN)

The brown tree snake is an introduced species on Guam, with numbers now hitting 1 million.

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(CNN) -- They creep up utility poles, slither into toilets, scale fences and hunt down their prey, usually birds, with striking success, attacking most often in the dark of night.

Experts say an estimated 1 million brown tree snakes currently prowl the Pacific island of Guam, endangering humans, causing frequent power outages and wiping out 10 species of birds and bats and threatening several others.

Most of the damage done in Guam is irreparable. And authorities fear the ecological disaster could just be beginning if the mildly venomous snakes escape the island and then reproduce in large numbers.

Placing thousands of traps throughout Guam, authorities have reduced the number of snakes in some of the island's more "high-risk" areas. But the U.S. government's visible efforts to curb the slithering species' migration -- including snake-sniffing dogs and specially designed "snake-proof" fences at Guam airports and ports -- have not been a total success.

Authorities said the snakes have colonized at least two other islands near Guam, and have been captured at airports in Hawaii, Texas and Spain. Michael Kuhlman of the Guam Department of Agriculture says the snakes would particularly thrive -- and would be near impossible to root out -- along the U.S. Gulf Coast.

"Really, people don't understand what this animal is capable of doing," said Mike Pitzler of the U.S. Department of Agriculture.

Birds most threatened

All the brown tree snakes in Guam, according to DNA studies, descended from a single female who apparently stowed away in a shipment of military cargo from New Guinea about 50 years ago.

The snakes, the longest of which measured 10.5 feet long, are characterized by their "very prominent eyes," explained Kuhlman.

Because the snakes are nocturnal, most people -- including the thousands of tourists who visit Guam every year -- have never seen them. But the snakes have had a definite human impact, causing frequent power failures and even infiltrating some homes.

Several years ago, Ernie Matson spotted a brown tree snake trying to eat his baby boy.

"I looked at his crib, and he had the snake's tail wrapped around his head and the snake's head wrapped around his leg," recalled Matson, "and [the child] was busy, 10 months old, holding onto the crib trying to pull the snake off him."

Yet the brown tree snake typically avoids humans, instead prowling the forests to feed on wildlife that evolved in Guam without any defenses against a predator like this.

The Guam rail, a flightless bird unique to the island, is one of the 10 species of birds on the island that the snake has hunted to extinction.

Almost all the island's Mariana crows are gone, and only a small colony of fruit bats evaded the snake in a remote hideout. Tens of thousands of fruit bats once lived on the island, dispersing seeds and pollinating the island's forests.

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