Last September we told you about how snakes are turning Guam into a spider-infested horror show. The island's brown tree snake population has reached epic proportions and is now threatening Guam's native bird species, along with neighboring islands. But where the U.S. government dropped shells on the island back in 1944, it's now planning to cover parts of it with something entirely different: dead mice laced with painkillers.
The highly invasive brown snake was introduced to Guam shortly after World War II. In just a matter of four decades, these snakes decimated 10 out of 12 native bird species, with the remaining two species forced to live in small areas, protected by snake traps.
Guam may be somewhat of a lost cause, but the real fear is that these snakes may eventually make their way to Hawaii — which would be a disaster to say the least. A 2010 study estimated that brown tree snakes would cause between $593 million and $2.14 billion in economic damage each year if they become established there. They would likely cause power outages, and a resultant decline in tourism.
To prevent this from happening, the U.S. spends more than $1 million each year to make sure airplanes and cargo are snake-free as they leave the American territory.
But starting this April, a new plan will be put into effect. A toxic mice drop will target snakes near Guam's Andersen Air Force Base — a high-risk vector area. And interestingly, the mice will be laced with acetaminophen, a substance that's toxic to brown snakes. U.S. government scientists have created a plan in which the dead 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.
"One concern was that crows may eat mice with the toxicant," said William Pitt, of the U.S. National Wildlife Research Center's Hawaii Field Station. "However, there are no longer wild crows on Guam. We will continue to refine methods to increase efficiency and limit any potential non-target hazards."
The goal, the scientists say, is not to wipe out the snakes, but to control and contain them.
Images: Janelle Lugge/Shutterstock, Eric Talmadge.