ANDERSEN AIR FORCE BASE, Guam » Dead mice laced with painkillers are about to rain down on Guam’s jungle canopy. They are scientists’ prescription for a headache that has caused the tiny U.S. territory misery for more than 60 years: the brown tree snake.
Most of Guam’s native bird species are extinct because of the snake, which reached the island’s thick jungles by hitching rides from the South Pacific on U.S. military ships shortly after World War II. There may be 2 million of the reptiles on Guam now, decimating wildlife, biting residents and even knocking out electricity by slithering onto power lines.
More than 3,000 miles away, Hawaii environmental officials have long feared a similar invasion — which in their case likely would be a “snakes on a plane” scenario. That would cost the state many vulnerable species and billions of dollars, but the risk will fall if Guam’s air-drop strategy succeeds.
“We are taking this to a new phase,” said Daniel Vice, assistant state director of U.S. Department of Agriculture’s Wildlife Services in Hawaii, Guam, and the Pacific Islands. “There really is no other place in the world with a snake problem like Guam.”
Brown tree snakes are generally a few feet long but can grow to be more than 10 feet in length. Most of Guam’s native birds were defenseless against the nocturnal, tree-based predators, and within a few decades of the reptile’s arrival, nearly all of them were wiped out.
The snakes can also climb power poles and wires, causing blackouts, or slither into homes and bite people, including babies; they use venom on their prey but it is not lethal to humans.
The infestation and the toll it has taken on native wildlife have tarnished Guam’s image as a tourism haven, though the snakes are rarely seen outside their jungle habitat.
The solution to this headache, fittingly enough, is acetaminophen, the active ingredient in painkillers including Tylenol.
The strategy takes advantage of the snake’s two big weaknesses. Unlike most snakes, brown tree snakes are happy to eat prey they didn’t kill themselves, and they are highly vulnerable to acetaminophen, which is harmless to humans.
The upcoming mice drop is targeted to hit snakes near Guam’s sprawling Andersen Air Force Base, which is surrounded by heavy foliage and if compromised would offer the snakes a potential ticket off the island. Using helicopters, the dead neonatal mice will be dropped by hand, one by one.
U.S. government scientists have been perfecting the mice-drop strategy for more than a decade with support from the Department of Defense and the Department of the Interior.
To keep the mice bait from dropping all the way to the ground, where it could be eaten by other animals or attract insects as they rot, researchers have developed a flotation device with streamers designed to catch in the branches of the forest foliage, where the snakes live and feed.
Experts say the impact on other species will be minimal, particularly since the snakes have themselves wiped out the birds that might have been most at risk.
It appears the effort to eradicate the notorious brown tree snake on Guam and keep it from infesting Hawaii will not fall victim to congressional budget tightening – at least for now.
The program was on the verge of being canceled this week because the fiscal year is ending and Congress has imposed a moratorium on the type of earmark funding that has kept it running for years.
At the last minute, the Defense and Interior departments agreed to pitch in $2.9 million to rescue the effort to secure ports and kill off the snakes for the next nine months, according to the U.S. Department of Agriculture.
The brown tree snake was introduced on Guam following World War II and has since decimated native bird species and plagued the island with electrical blackouts caused by snakes infesting transformers. Meanwhile, scientists fear the pest could be accidentally imported to Hawaii and severely damage the island environment and cost hundreds of millions of dollars – or even billions – in economic losses.
“We don’t want a break in service, obviously, and so that’s why there was very much concern over the budget situation,”
In the late 1920s, people intentionally introduced birds known as Japanese white-eyes into Hawaiian agricultural lands and gardens for purposes of bug control. Now, that decision has come back to bite us. A recent increase in the numbers of white-eyes that live in old-growth forests is leaving native bird species with too little to eat, according to a report published online on September 17th in Current Biology, a Cell Press publication. The findings show that introduced species can alter whole communities in significant ways and cause visible harm to the birds that manage to survive.
"Native Hawaiian songbirds cannot rear normal-size offspring in the presence of large numbers of introduced Japanese white-eyes," said Leonard Freed of the University of Hawaii at Manoa. "Their growth is stunted."