A brown tree snake in Queensland, Australia (file photo).
Photograph by George Grall, National Geographic
Published September 24, 2010
Dead mice packed with drugs were recently airdropped into Guam’s dense jungle canopy—part of a new effort to kill an invasive species of snake on the U.S. Pacific island territory.
In the U.S. government-funded project, tablets of concentrated acetaminophen, the active ingredient in Tylenol, are placed in dead thumb-size mice, which are then used as bait for brown tree snakes.
In humans, acetaminophen helps soothe aches, pains, and fevers. But when ingested by brown tree snakes, the drug disrupts the oxygen-carrying ability of the snakes’ hemoglobin blood proteins.
“They go into a coma, and then death,” said Peter Savarie, a researcher with the U.S. Department of Agriculture (USDA) Wildlife Services, which has been developing the technique since 1995 through grants from the U.S. Departments of Defense and Interior.
Only about 80 milligrams of acetaminophen—equal to a child’s dose of Tylenol—are needed to kill an adult brown tree snake. Once ingested via a dead mouse, it typically takes about 60 hours for the drug to kill a snake.
“There are very few snakes that will consume something that they haven’t killed themselves,” added Dan Vice, assistant state director of USDA Wildlife Services in Hawaii, Guam, and the Pacific Islands.
But brown tree snakes will scavenge as well as hunt, he said, and that’s the “chink in the brown tree snake’s armor.”
Snakes Pests Decimated “Naïve” Wildlife
The brown tree snake is an arboreal species native to Australia, Papua New Guinea, and several Pacific islands. The snake preys on birds, lizards, bats, and small mammals.
Inadvertently introduced to Guam (map) from the Solomon Islands after World War II, brown tree snakes are responsible for the extinction or severe reduction of several of the island’s native species.