Drugged Mouse Cadavers Dropped Into the Jungles of Guam to Kill Snakes

By J.J. Gould
Ever since brown tree snakes were inadvertently brought into Guam from the Solomon Islands after the Second World War, they've been going about their natural business of targeting bats, birds, lizards, and small mammals -- in the course of which they've (also inadvertently) wiped out or significantly reduced a number of the Pacific island's native species. Over the intervening decades, scientists have developed a range of countermeasures, including the use of traps, snake-detecting dogs, and spotlight searches along airport and seaport fences. With mixed success, these strategies have focused on preventing the snakes from getting onto planes or ships headed to other islands, like Hawaii, where it's expected they would do even more damage. But the new plan is to get proactive and go after the snakes where they live -- in the jungle -- by means of lethal / over-the-counter drugs:

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."

For more on how to increase the odds that airdropped mice get caught in the high tree branches where brown snakes live, why most other species that might be lured by the mice are already gone, and the hows and whys of radio-tagging bait, read the full story at National Geographic.

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