Study points to global snake decline
By Jeremy Hance, www.mongabay.com
June 09, 2010 A number of reports over the last decade have shown amphibians, lizards, fish, and birds facing steep population declines across species and continents, providing further evidence that the planet is undergoing a mass extinction. Now a new study in Biology Letters adds another group of animals to that list: snakes. Studying 17 snake populations from seven species in Europe, Africa, and Australia, researchers found that 11 of the populations (64 percent) suffered declines with some populations dropping as much as 90 percent. At the same time only one of the populations (less than 6 percent) rose. Although separated geographically, the decline for each of the populations began around 1998. Researchers are not sure what caused the decline, although 1998 was the warmest year on record leading scientists to speculate that climate change may, at least in part, be responsible. Other factors could include habitat decline and a drop in prey populations. Given the small sample size—seven species and 17 populations—scientists say that more data is needed on snake populations in order to understand the exact causes behind the observed decline. “The problem is that snakes are very difficult to work on and there are very few long-term individual based population studies of them,” Chris Reading, lead author of the study, told The Guardian. “If, as a result of our paper we can get herpetologists around the world to analyze their data again then we may start to build a clearer picture of what may be happening to snakes and what the causes of any declines may be.” While snakes are often one of the top animals that people fear, Reading told the Christian Science Monitor that snakes are important for ecosystems and humans: they provide pest control. “They are the top predator in many ecosystems in which they occur. If you get rid of a top predator, it will have a knock-on affect on all those species on which they prey […] You take out the predator and suddenly you have an increase in the pest species.” Snakes prey heavily on rodents, and in turn help protect crops around the world. As of last year the IUCN Red List estimated that 31 percent of reptiles were threatened with extinction.
