Snake conservation in anthropized landscapes: considering artificial habitats and questioning management of semi-natural habitats

The intensification of human activities is responsible for habitat loss which is the major cause of biodiversity regression. In this context, it becomes critical to consider with more attention highly transformed or artificial habitats that may have a significant value for biodiversity conservation. It is also equally important to evaluate the significance of management measures in remaining semi-natural habitat. Squamate reptiles (lizards and snakes) usually have limited dispersal capacities and are consequently particularly vulnerable to habitat changes. We studied the abundance of an endangered species, the smooth snake (Coronella austriaca), in 112 sites located in the southern part of Belgium. We wanted to compare population size and density in a semi-natural habitat (dry grassland) and two artificial ones (rocky habitats and railway). We also wanted to compare snake density in grasslands depending on management measures (either mowing, grazing, or no management). Our results suggest that smooth snake population sizes are low with fewer than 20 individuals on 85% of the sampled sites. Highest density and population sizes were reported along railways and in artificial rocky habitats when compared with grasslands. Population density was lower in nature reserves reflecting notably the negative effect of management (grazing). Our study suggests that transformed habitat can provide significant structural diversity and can be beneficial as long as human pressure remains low. In turn, management measures deployed in semi-natural habitats may dramatically affect microhabitat diversity and significantly impact squamate populations.