Thursday, December 30, 2010

World's Largest Snake Threatened with Extinction by...Hikers and Backpackers?

   Imagine my surprise and interest when I noticed a newspaper article about an anaconda population crash in Bolivia.  Anaconda's are the world's heaviest snake and these impressive animals can be found swimming through the swamps of South America (not Alabama).  Although just about everyone has heard of anacondas, it's not a species we know too much about.  Some anacondas live in a grassy wetland habitat known as the Pantanal, and there has been some research conducted on these animals.  But, other anacondas live in the deepest darkest recesses of the tropical jungle, and it's hard to get in there to study these beasts.

    Snakes are secretive animals.  For every individual snake you see, it's almost impossible to know if there's another one hiding nearby that you didn't see.  Or perhaps there were actually two more...or a hundred.  This uncertainty makes it very hard to determine whether a population of snakes is increasing, decreasing, or staying the same.  Perhaps that's why I thought the bold headline, "World's biggest snake threatened by backpackers" was so intriguing.

  The article makes some more bold statements about anaconda population crashes and quotes a few biologists and organizations that affirm that this crisis is occurring.  Although the article makes a couple mentions about various studies on the subject, I could not actually track them down.  If a biologist claims that wildlife populations are changing, they should be basing this conclusion on scientific data.  These data (and associated conclusions) should appear in a scientific journal.  If it hasn't appeared in a scientific journal, then we don't know that it has been reviewed and approved by other scientists.  It was a red flag for me that there were apparently no scientific studies or articles that described this apparent snake population crash.

  But, I was prepared to give everyone the benefit of the doubt until I read further.  The take-home message of the article appears to be that, 1) hikers and other tourists in Bolivia are wearing insect repellent when they venture into the jungle, 2) this insect repellent contains dangerous chemicals, and 3) anacondas are being harmed because anacondas, like other amphibians, have soft and permeable skin that absorbs these dangerous chemicals when they seep into the water.

   Say what?  Anacondas aren't amphibians.  They're not even close, they're reptiles.  Anacondas don't have permeable skin either, they have scales just like all other reptiles.  It's true that there is some concern about how amphibians respond to chemicals in their environment, but I'd be very surprised if the amount of chemicals coming off of tourists and into surrounding wetlands is large enough to affect any animal, amphibian or not.  If we were talking about industrial waste or pollution, that's a different issue entirely. In addition, I am always careful not to handle a frog or salamander (actual amphibians) on the rare occasions that I have insect repellent or sunscreen on my hands because direct contact could harm them.  But, I just can't get over how much insect repellent I would need to have on my hands to kill animals swimming around in a swamp, especially those as huge as anacondas.  Given the glaring classification error in the article, I have a hard time accepting the entire premise, which was suspect to begin with.

D. A. Steen (2010). Snakes in the grass: secretive natural histories defy both conventional and progressive statistics. Herpetological Conservation and Biology, 5, 183-188

1 comment:

Joy K. said...

An amphibian anaconda? Hm. Interesting. Yes, that does make one doubt the "study," doesn't it?

This post is at the House of Herps Carnival at my blog, The Little House in the Not-So-Big Woods.