Thursday, March 07, 2013

Brown Tree Snake

A couple of years ago I read an interesting book by Alan Burdick entitled “Out of Eden- An Odyssey of Ecological Invasion”.  It is full of detailed information about the introduction, both deliberate and accidental, of plants and animals that are not native or non-indigenous to the country it was introduced into. These alien biota literally take over and threaten if not wipe out entirely, the native or indigenous plants and animals throwing entire ecosystems into disarray. In the book the author stated Harvard biologist Edward O. Wilson’s claim “that the introduction of alien species is second only to habitat destruction as the leading cause of extinctions worldwide.” Chapters 1-4, “In the Serpent’s Embrace”, were particularly interesting and dealt with Boiga irregularis, the Brown Tree Snake, native to Australia and Papau New Guinea. This nocturnal, arboreal reptile has inflicted immense havoc upon the ecosystem of the island of Guam, since being introduced from the wheel wells of a cargo plane following World War II. Burdick compares the spread of this snake to a disease that is spread by a vector of “human commerce: planes, ships, vehicles of cargo.”
The book states that, since the birds of Guam had no discernible predators at the time of the snake’s introduction, they were not prepared for the devastation that was about to pounce upon them.  This resulted in the snake literally consuming and extirpating nine of the 12 species of forest birds on this tiny island.  Birds included are: Bridled White-eyed (Zosterops conspicillatus), Rufous Fantail (Rhipidura rufifrons uraniae), Guam flycatcher (Myiagra freycineti), Cardinal Honeyeater (Myzomela cardinalis saffordi), Micronesian Kingfisher (Halcyon c. cinnamomina), Guam Rail (Rallus owstoni), and three sea bird species.  Now that the bird population has declined the island is experiencing a surge in spider populations. (less spider-eating birds = more spiders).  Burdick says “No previous record existed of a snake obliterating an entire island of birds….”  And in Julie Savidge’s 1987 case study she states “This is the first time a snake has been implicated as an agent of extinction.” 
Since reading this book I came across an article on Science Line entitled “Flying Mice Target Tree Snakes”, which details a plan to get control of these snakes in a somewhat interesting approach.  The U.S. Department of Agriculture’s Wildlife Services in Hawaii, Guam, and the Pacific Islands “parachuted” dead mice laced with painkillers (acetaminophen- which when consumed is deadly to these snakes) from helicopters into the dense foliage near Anderson Air Force base on the island.  The parachuting device (basically streamers) is designed to get entangled in the heavy foliage where the snakes spend most of their time.  

Since Guam exports many things the fear is that one or more of these snakes will hitch-hike a ride on a plane to Hawaii (or anywhere else for that matter), which could then become the next Guam.  Believe it or not, this snake once made its way to my home state of Texas in Corpus Christi in 1993. It was discovered in a crate of household goods that had been shipped there to Ingleside Naval Station and was killed upon discovery.   If I come across any updates on this interesting story I’ll be sure to post something here.

References and Suggested Reading:

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