Snakes are commonly found across a range of habitats, yet they tend to be quite sedentary, especially among European species. Their choice of habitat is largely influenced by microclimatic and microhabitat conditions, with key factors being the availability of food and shelter. Additionally, age, sex, and population dynamics can play a role in habitat selection. While many studies have focused on the broad environments in which these species can be found, few have delved into the specific microhabitat conditions that have a more direct impact on their site preferences.

In this context, a paper soon to be published in Acta Herpetologica investigates the ecology of Vipera ammodytes across five populations in western Bulgaria. These study areas, positioned along a latitude gradient, are characterized by distinct ecological and climatic conditions. Each site was visited multiple times on days when the air temperature was suitable for snake activity. Vipers and their shelters were located through visual observation and active searching. Each individual encountered was captured, weighed, measured, photographed, and marked, while the microhabitat characteristics of each capture site were meticulously recorded. 

The studied populations of Vipera ammodytes demonstrated a clear preference for rocky habitats and microhabitats, while actively avoiding bare environments, agricultural areas, and deciduous forests. Within each population, the niche breadth was remarkably narrow, suggesting specialized habitat use. However, latitude did not appear to influence habitat choice significantly. Instead, habitat availability emerged as the primary factor shaping habitat selection, along with seasonal changes and local microclimatic conditions.

Microhabitat selection, on the other hand, exhibited some latitude-dependent patterns. For instance, the population from northern Bulgaria showed a marked preference for stony and rocky microhabitats with sparse vegetation. In contrast, the southernmost population favored microhabitats with a balanced coverage of rocks, stones, grasses, and shrubs. These differences in microhabitat use may stem from interspecific competition or from variations in local terrain and thermal conditions.

Evidence of seasonal variation in habitat preference was observed in at least a few of the studied populations. This seasonal variation is likely influenced by site-specific factors such as thermal conditions, insolation, availability of food and water, and access to suitable shelter.

The study, in addition to being the first study to detail so comprehensively the habitat and microhabitat preferences of Vipera ammodytes, provides valuable insights into how multiple factors—such as microclimatic conditions, resource availability, and interspecific interactions—interplay to shape the ecological strategies of this species. 

Preview the full manuscript here.     

See you in two weeks!