Snakes have long been vilified in popular media – but do they deserve such a bad reputation? Many people believe otherwise, with 16th July marking World Snake Day and providing the opportunity to learn more about these fascinatingly-misunderstood animals. Dr Xavier Bonnet, Director of the Centre d’Etudes Biologique de Chizé at the French National Centre for Scientific Research (CNRS), discusses the history of our relationship with snakes and shares his experience of encouraging reconciliation.
Snakes appeared long before human lineages, approximately 150 million years ago. In the course of their long history, these elongated limbless lizards successfully colonized marine and terrestrial habitats and they survived the K/T crisis. Currently more than 3,500 species have been identified, a number greater than most people may imagine, and that increases every year as new species are recognized and described. Although the hypothesis has not been rigorously tested, many scientists believe that the extraordinary physiological and behavioral plasticity of snakes has been a key to their evolutionary success. All snakes are predators and many possess potent venoms, an attribute that makes them highly-efficient hunters. They often occur in large numbers, and several populations exhibit extremely high biomass (e.g. >10 kg of top predators/ha). The low and highly variable metabolic rate of snakes facilitates adaptive responses to environmental fluctuations. Unsurprisingly, recent research has demonstrated that snakes play fundamental roles in the functioning of many ecosystems.
Yet snakes are famous for other reasons as well. The extraordinary body flexibility of snakes captured the attention of early humans and fascinated artists. In virtually all mythologies, the sacred serpent is associated with rivers, rainfall, rainbow, telluric forces and thus creation tales (i.e. the rain fertilizes the earth). During millennia snakes have been carved, painted and celebrated as powerful, dangerous, but basically positive deities (symbols like the penis are virtually non-existent in prehistoric and archeological artifacts and mythologies). The caduceus (an ancient Greek or Roman herald’s wand which typically features serpents twined round it) is one of the many symbols of this long period of respect, although snakes were also routinely consumed for their meat.
Unfortunately for snakes, religions and civilizations also evolve. The sacred serpent has been demonized. Tens of millions of snakes are killed every year, primarily in Asia, to supply food markets and also for the luxury leather industry in “developed” countries. Snakes are also savagely massacred in western countries. During rattlesnake roundups huge numbers of snakes are decapitated, the mouth of some of them is sewn shut without anesthesia, and children dip their hands into the snakes’ blood to form handprints on white panels. Elsewhere live pythons are inflated with compressed air to facilitate skinning; the agony is long. These atrocities would be unacceptable for mammals, but not for hated animals. Nowadays, snakes are declining worldwide, with little concern from the public. A lethal cocktail of habitat destruction, pollution and direct killing is resulting in population collapses. For example, in agricultural landscapes of western central France snakes were abundant few decades ago. Large scale extirpation of hedges deprived snakes and their prey of shelters, pesticide abuse broke down trophic chains, and reproductive individuals have been killed in vast numbers on the roads. At a landscape scale and across immense areas, approximately 90% of the snakes have been removed. Sadly this situation is widespread across the planet, both on land and in the oceans, and it is worsening rapidly. Funding agencies are reluctant to invest in the conservation of unpopular organisms, especially in Europe. A handful of projects focused on almost-extinct species have been funded, leaving the vast majority of snake species unprotected.
Is all hope lost? We recently embarked on a program to reverse this depressing slide of snake populations towards extinction. For more than 10 years, we have been trying to reconcile humans and snakes. For the first time we set up a conservation program to promote snakes in a very challenging context: a large suburban park surrounded by cities and annually used by more than 70,000 citizens for recreational activities and facilities (walking, jogging, cycling, playgrounds). Urban parks are intensively managed to please the public; and unlike squirrels and birds, snakes are unwelcome. Polls revealed a marked preference for well-spaced large trees and extensive mowed areas – habitats that are unsuitable for reptiles. In the park named “Ark of Nature” we cut down trees to promote the growth of shrubs (e.g. brambles, gorse, hawthorn) and to create open habitats. People perceive shrubby and brambly areas as untidy and disheveled. To encourage acceptance of this non-traditional parkland, we invited schoolchildren, firemen, and hunters to participate in the project via broad media coverage. We used different experimental treatments and long-term mark-recapture surveys to obtain statistically robust results on the impact of our habitat manipulation and education program on snake populations.
The study was launched in 2006. More than 10 years later, we can claim success. Newly created open and shrubby habitats have been colonized by four species of snakes. More than one thousand snakes have been individually marked and many have been recaptured time and again, principally in the open and bushy areas. The most abundant species is the asp viper, a dangerous venomous snake. Hundreds of schoolchildren have participated, and thousands of adults have been informed or have attended conferences or field trips. All were enthusiastic. This study is encouraging as it demonstrates that simple management strategies that favor “unpopular” organisms are feasible, even in densely populated areas, providing that educational activities are conducted in parallel.
For more information:
Bonnet et al. (2016) Forest management bolsters native snake populations in urban parks. Biological Conservation, 193, 1-8.
Reading et al. (2010) Are snake populations in widespread decline? Biology Letters, 6, 777-780.