Brown Tree Snakes in Guam: a place for everything and everything in it's place
US military transport carriers may have been the vessel used by Brown Tree Snakes (Boiga irregularis) to invade and successfully conquer Guam. Towards the end of World War II, these Australian native reptiles were busy with an assault of their own; the extirpation of Guams' native birds, bats and lizards.
Dramatisations aside, this adaptive reptile did in fact wipe out the fauna of the island in just a few short years. Today only 9 native birds have survived the onslaught, every one of which is now considered extremely rare. In fact one endemic rail is now represented only by a small collection bred in captivity to ensure its survival (Fritts and Leasman-Tanner 2001). As a result of the extinction of the island's insectivorous birds, insects and spiders alike have radiated dramatically. For instance, there now exists forty times as many spiders on Guam than on neighbouring Islands (Braun 2012). It is quite clear that these animals are thriving in le of predation from birds. The forests of Guam are an eerie place now, devoid of bird song and blanketed in spider webs.
As Australians, we're all familiar with the devastation that pests can have on the natural environment, but many of us underestimate the significant predatory power that snakes have in the ecosystem. The Brown Tree Snakes' in Guam have shown us that snakes are an important player in ecosystem dynamics. If we continue to preserve old ideologies that foster negative feelings towards snakes, we risk losing them altogether and the consequences are likely to be profound.
Although we are far from understanding the complex roles that the highly diverse and abundant snake fauna plays in ecosystem ecology, hopefully we can appreciate that snakes like all other organisms are apart of something greater, an all encompassing delicately balanced food web, that when tampered with can result in great cascading impacts that ultimately affect us too.
Braun, D. (2012) Spiders take control as birds fade from Guam. Retrieved from: http://newswatch.nationalgeographic.com/2012/09/16/spiders-take-control-as-birds-fade-from-guam/
Fritts, T.H., and D. Leasman-Tanner. (2001) The Brown Treesnake on Guam: How the arrival of one invasive species damaged the ecology, commerce, electrical systems, and human health on Guam: A comprehensive information source. Retrieved from: http://www.fort.usgs.gov/resources/education/bts/bts_home.asp
Captured Brown Tree Snake at Benaraby, QLD