The first study showing an alarming decline in populations of different snakes was published this month ( Reading et al. 2010. Are Widespread in snake populations decline? Biology Letters, doi: 10.1098/rsbl .2010.0373 ). This study was a massive global echo, in very many major television channels (Eg BBC, National Geographic, ABC, Al Jazeera ...), radio, websites and newspapers. Just type "snake decline" on google for testing.
With our colleagues in the Australian, British, Italian, Nigerian and ourselves (France), we compared our data sets on long-term follow that out over several decades on several continents. On 17 populations (8 species of snakes, including vipers, elapid, Colubridae, PythonIDE), 11 experienced a catastrophic decline and show no sign of recovery. The others are stable (or very slight increase). All populations followed in unprotected areas have seen their numbers reduced considerably. Most likely due to habitat degradation (loss of shelter, excessive use of pesticides ...). This is precisely the case for snakes studied in France who suffer greatly from the sudden intensification of agriculture (consolidation very strong, serious pollution ...) to the detriment of agriculture in line with the protection of environment. Stable populations are all in protected nature reserves. However, populations have declined even though they were in protected areas, indicating the existence of mysterious and probably still causes poly-factorial. This kind of widespread phenomenon is reminiscent of the global drop in the numbers of amphibians. Finally, the declines are characterized by declines in populations synchronized and relatively strong (between 1998 and 2002).
Our findings are disturbing and we encourage our colleagues to compare their data with ours. If our conclusions are asserting themselves, the consequences could be dramatic. The only positive is the huge advertising in the media, always carried out in an optical storage and emergency to protect the reptiles.
Xavier Bonnet
CEBC-CNRS
The asp, a snake in decline in France. (© J.-P. Vacher)
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