How to Get Rid of Invasive Tree Snakes: Bomb Them With Parachuted, Poisonous Mice

By Jennifer Welsh | September 23, 2010 1:04 pm

BTSThe USDA and the EPA are in cahoots, scheming against Guam’s invasive brown tree snakes, or are they throwing a party?

Using streamers, cardboard, some acetaminophen (aka Tylenol, aka hangover medicine), some dead mice and a helicopter, the team is looking to destroy the island’s invasive snake population.

Guam has only two snake populations. The first is the island’s only other snake: a tiny, blind worm-like little guy. The second, and more obvious, is the invasive tree snake, which is mildly venomous, can reach 11 feet long, and can be found at up to 12,000 snakes per square mile. The native snake is no competition for this invasive beast, which was introduced to the island in the early 1950’s and quickly decimated native forest species, including all of the forests vertebrates.

It has also invaded the homes of the island’s human inhabitants, causing power outages by messing with electrical systems and biting and scaring people in their sleep. (And there is not much more scary than a snake biting you in your sleep.) The USDA and EPA have been working for decades to solve this problem, but nothing was working.

The new plan: kill the snakes by feeding them acetaminophen, which even in small amounts is poisonous to them. (The typical dose for humans is about 1000 milligrams; a mere 80 milligrams will kill a tree snake.)

“The discovery that snakes will die when they eat acetaminophen was a huge step forward,” Anne Brooke, conservation resources program manager for Naval Facilities Command Marianas, said Thursday [September 2]. “The problem was how you get the snakes to eat it.” [Stars And Stripes]

The solution: the snakes aren’t big pill poppers, so the researchers decided to deliver the poison dose by stuffing Tylenol tablets in the mouths of dead mice, an appetizing snake snack.

The problem with the solution: many of the snakes live in the wild, unreachable forest canopy. To get the mice to drop specifically onto the high branches and not to the forest floor, where they could be eaten by other animals, would require some special equipment,

The solution to that problem: using streamers and cardboard from a party store, researchers at the USGS were able to fashion a parachute, which would land the mice in the canopy, where the tree snakes gobble them up and promptly die.

The USDA started testing the new parachutes earlier this month, dropping 200 of the traps into the forests around Naval Base Guam. The bait was so successful, they expect a full scale roll out of the program to happen soon, Dan Vice, assistant state director of USDA Wildlife Services in Hawaii, Guam and the Pacific Islands told Stars And Stripes:

The USDA has a grant from the Department of Defense to expand the control efforts on Guam military bases in 2011. Eventually, Vice said, he hopes the method can be used island-wide in the near future. “What we are doing now is finding out the hiccups in the system,” he said. “The next step will be 100 hectares (247 acres) of forest area on Andersen Air Base.”

The USDA team is currently looking for cheaper ways to poison the tree snakes, since the mice (coming in at 40 cents each plus shipping) are getting expensive. One option is to “treat” beef cubes with “decomposition extracts” from 48 hour old dead mice. Tasty!

Related content:
Discoblog: “Spitting Cobras” Don’t Really Spit After All
80beats: Attempt to Control Invasive Species Backfires Spectacularly on an Antarctic Island
80beats: How to Control Florida’s Invasive, Occasionally Killer Pythons?
Discover magazine: Is That a Dead Mouse You’re Cloning?
Not Exactly Rocket Science: The snake that eats toads to steal their poison

Image: Wikimedia Commons/Orionhound

  • Rhacodactylus

    Wow, if only I could afford weed that good.

  • Nemesis


    I’ve got some weed that’ll put your snake in the dirt.

  • Jockaira

    My calculations based on surface area of Guam and the above population density of the brown tree snakes (do they come in green, my favorite color?) shows that there are about 2.5 million of these little critters hanging out in the treetops. At 40¢ each for a last snack, the budget to eradicate all of these comes to more than $10 million…and that’s if you don’t consider their reproductive prowess…so you better get on this, and fast to save money!

    I’m sure the Guamians would be eager to train for the new federal position of “mouse-stuffing.” It should cure any unemployment problems for at least the next decade, and like most federal programs, the effectiveness will be diluted by spotty or delayed applications…so this boondoggle has the possibility of lasting for several eons.

  • Chris

    Quoted from this post:
    “The first is the island’s only native snake: a tiny, blind worm-like little guy.”

    Rhamphotyphlops braminus also is not native to Guam. It is found throughout Asia and Africa and most likely arrived on Guam when people did. You find them in the US also, usually in potted plants (hence the common name “flower pot snake”.)

  • Elissa

    The only time I have ever cheered for mice!

  • UncleLar

    Jockaira – hope you are better at your science than your math.

    First of all, the article says the snakes can be found at densities UP TO 12,000 per square mile. The only way you get to 2.5 million snakes would be if the entire island averaged that density rather than maxed out at that density.

    Secondly, even if there were 2.5 million snakes on the island. At 40 cents a dose for the mice, that still only works out to $1M not $10M.

  • Jennifer Welsh

    Hey Chris,

    Thanks for the note, sorry for that confusion. I fixed the post to reflect your comment. Thanks, all for commenting and reading!


  • Chris

    Hi Jen,
    You’re welcome – loved the post.

  • Jockaira

    Uncle Lar,

    Thanks for finding my misplaced decimal. Of course, I used the maximum density for the whole island, is it not customary in government projects to paint the most dire picture in order to ensure the maximum funding?

    And they’ll probably need that $10 million and more, “since the mice (coming in at 40 cents each plus shipping)” includes only the procurement costs for the mice. I read the article in “Stars and Stripes” about the same subject. That article avoided mention of the per capita cost of the mice but highlighted the delivery method (which this Discover item misses) because of the military slant.

    The 200 tylenol-stuffed mice in the original carpet-bombing were hand-dropped from a helicopter in order for the mice to be snagged in the forest canopies where the snakes live. I imagine that future drops will be contracted to civilian firms that will probably use civilian helicopters the usual operating costs of which are about $400 hourly at full amortization not counting flight personnel. Military helicopters would simply be too expensive and dangerous for such a task.

    That 40¢ a mouse is peanuts compared to the costs of delivering them where the snakes can easily get them

    So regardless of an assumption I made for comedic purposes and the misplacing of a decimal point, it looks like the eventual cost of this particular eradication might still be in the neighborhood of $10 million, or more. And there is no assurance that the species can or will be eradicated. It only takes two snakes (a male and a female) to start the whole thing over again, not to mention the continued casual importation of new snakes in inbound goods cargo, which is how they got there in the first place.

    The best they can hope for is to reduce and control the snake population using the methods above. Complete eradication would simply cost too much.

  • Ron

    It’s Guamanian, not Guamian.

  • Brian Too

    The mental image of people carpet bombing the island with little mouse corpses (with parachutes! Hepped up on Tylenol?!) is, well, mirth inducing to say the least. Are you sure some comedy group didn’t create this story? Let’s see, Monty Python? Carol Burnett? Mitchell and Webb? Marx Brothers? Jerry Seinfeld?

    Someone with a real fine sense of the absurd.

  • xenubarb

    If the brown snake eats carrion, this should be front page news. Snake owners know you can’t just throw in a cold, dead rat and expect it to be eaten. Now tie the rat to a string and throw it up in a tree.

    The brown snake is arboreal and feeds on birds, so what rocket scientists decided money could be wasted on dead mice and a rental chopper?


    Surely they could have come up with some other solution to this problem. First of all, it will take the snakes over 72 hours to die an agonizing death due to renal and liver failure. Sorry, but they are part of the ecosystem and the stupid US Dept of Agriculture sending poison mice raining down still can’t know the impact it will have on other species that may still get the mice and eat them but pretty sure they didn’t think of that one. Absolutely stupid, inhumane, incredibly costly and I’m sure no one cares about that either.


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