In February 2013, the U.S. government approved $8 million in funding for a program in Guam to use dead mice packed full of painkillers to combat a widespread infestation of brown tree snakes (Boiga irregularis). Arriving in Guam just after World War II, the brown tree snake found the island to be perfect hunting environment preying on many exotic birds and other vertebrates. The snake population has grown to unprecedented numbers and cause an average of 80 power failures a year (resulting in an estimated loss of $4 million annually). Additionally, there are numerous reports of the snakes attacking people.
After years of failed control tactics, the tree snake’s 2 weaknesses were identified: mice and Tylenol. The rear-fanged snake can be killed after consuming a relatively small amount of Tylenol and mice are one of their favorite meals. Flying at low altitude at slow speeds, the acetaminophen-laced dead mice are parachuted down from helicopters into the forest canopy where the snakes can take the bait.
Certified pest control applicators in the helicopters will oversee the execution of the dropping of the mice baits out of the helicopter. Focusing on the area around Guam’s Anderson Air Force Base, the helicopters can drop as many as 2,000 mice in a single day.
The mice are filled with 80 ml of Tylenol and are attached to tissue paper and cardboard. The baits can kill a snake within 72 hours. The dead mice have very low toxicity to other mammals like pigs and dogs. Unlike some snake species, the brown tree snake will eat animals that are already dead.
Bird populations have declined since the snake’s arrival from the island to the point where remaining populations in Guam are quite small and mostly limited to reserves protected from the invasive reptile. In the last 30 years, 10 out of 12 native forest bird species in Guam have disappeared. It is estimated that the snake population has reached 2 million on the island with a density of 13,000 per square mile that stacks up against some of the most snake-infested locales in the world.
For more weird rodent facts, check out our recent blog post on strange rat facts.
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