Snakes in decline

Snake populations are dwindling at unprecedented rates, adding to an alarming list of declining vertebrate populations across the world.  Startling results revealing the extent of snake population decline are published this week in Royal Society journal Biology Letters.  The study is the first ever documented evidence of such a decline based on long-term studies of snake populations.

While the causes for the diminishing numbers of snakes are unclear, the scientists responsible for the ambitious study suggest that habitat loss, pollution and declining prey numbers may all have contributed to plummeting populations.  The fall in numbers is particularly worrying as many of the species studied are top predators, meaning that their decline could cause serious disruption to many ecosystems.  The study showed that in many cases, populations in diverse locations – from Nigeria to the UK – have collapsed at similar rates and in similar patterns, which suggests that there may be a single root cause of the decline.

However, as yet the causes of the decline are far from clear.  While a minority of the populations studied were found to be maintaining numbers, all of these came from protected wildlife areas.  Worryingly, not all of the groups studied in protected areas were stable; in fact, eight such populations were discovered to be declining rapidly. 

Overall, almost two thirds of the species studied experienced significant population reduction over the course of the study and none have showed any signs of recovery so far.  Dr Chris Reading of NERC’s Centre for Ecology and Hydrology, one of the authors of the international study, said that “snake researchers should work more closely with one another to better identify the factors responsible for the widespread population declines of snakes in order to understand, stop and ultimately reverse them”.