Habitat use of the Aesculapian snake at different spatial scales

Retrospective Detection of Ophidiomyces ophidiicola from Snake Moults Collected in Bieszczady Mountains, Poland

Ophidiomyces ophidiicola, the causative agent of ophidiomycosis, poses a potential threat to wild snakes worldwide. This study aimed to retrospectively investigate the prevalence of O. ophidiicola in archived snake moults collected from the San River Valley in the Bieszczady Mountains, Poland, from 2010 to 2012. Using qPCR for O. ophidiicola detection and conventional PCR for clade characterisation, we analysed 58 moults and one road-killed specimen of Zamenis longissimus and Natrix natrix. A novel combination of primers (ITS2L) was used to simultaneously confirm SYBR Green-based qPCR results and perform genotyping. O. ophidiicola has been detected from two Z. longissimus and one N. natrix specimens. The identified clade (I-B) is consistent with those found in wild snakes of eastern Europe and San River Valley, indicating that O. ophidiicola has been present in this region for at least a decade. This study underscores the value of historical samples in understanding the long-term presence of pathogens and highlights the potential role of environmental reservoirs in the persistence of O. ophidiicola. Our findings are crucial for informing conservation strategies for the endangered Aesculapian snake populations in Poland, emphasising the need for ongoing monitoring and habitat management to mitigate the potential impact of ophidiomycosis.

Climatic conditions and prevalence of melanistic snakes-contrasting effects of warm springs and mild winters

Climate change is one of the greatest challenges that wildlife is facing. Rapid shifts in climatic conditions may accelerate evolutionary changes in populations as a result of strong selective pressure. Most studies focus on the impact of climatic conditions on phenologies and annual cycles, whereas there are fewer reports of empirical support for climate-driven changes in the phenotypic variability of free-living populations. We investigated whether climatic variables explain the prevalence of colour polymorphism in a population of the grass snake (Natrix natrix) with two morphotypes, the melanistic and non-melanistic ones, in the period 1981-2013. We found that the prevalence of the black phenotype was negatively related to spring temperature and winter harshness, expressed as the number of snow days. According to the thermal melanism hypothesis, a high predation rate during warmer springs may override relaxed thermal benefits and vice versa, i.e. black individuals may perform better than typical ones when thermal conditions in spring are unfavourable. In turn, because they are smaller, melanistic individuals may be exposed to a higher risk of winter mortality, particularly during longer winters. We highlight the need for more studies on the effects of climatic conditions on temporal variation in melanism prevalence in other populations and species as well as in various geographic regions.

Age-Dependent Utilization of Shelters and Habitat in Two Reptile Species with Contrasting Intraspecific Interactions

Simple Summary

Intraspecific interactions are known to affect habitat use in birds and mammals but their role in spatial ecology of reptiles is far less recognized. Our comparative study shows that species known to exhibit intraspecific predation (smooth snake Coronella austriaca) express clearly different patterns of habitat and shelter occupancy than a species with no such cannibalistic behavior (slow worm Anguis fragilis). Specifically, juvenile smooth snakes prefer sites and shelters not occupied by the adults, even despite suboptimal habitat conditions. We propose that such division indicates an avoidance of predation pressure set by larger individuals on the younger and smaller ones. On the contrary, in slow worms no tendency for intraspecific avoidance are observed, since specimens of different ages commonly share the same area and shelters. This points to higher flexibility in habitat use in slow worms, while the smooth snake population is spatially structured, with juveniles dispersed to the margins of the population range. For endangered smooth snakes, habitat conservation should therefore include a wide buffer zone to maintain the youngest fraction of the population. Future studies on habitat utilization in squamates needs to pay more attention to the social cues, a commonly overlooked aspect in the spatial ecology of reptiles.

Abstract

Reptiles undergo worldwide decline driven mostly by habitat change. Detailed recognition of factors underlying spatial structure and habitat utilization is therefore a prerequisite of effective conservation of this group. While the body of data on spatial ecology of reptiles is rapidly growing, studies on social factors remain still underrepresented. We studied age-specific patterns of shelter use, range size, and habitat preferences in the context of intraspecific interactions in the smooth snake Coronella austriaca—known to exhibit intraspecific predation—and the limbless lizard slow worm Anguis fragilis—with no such behavior observed. Despite smaller availability of preferred microhabitats, juveniles of smooth snakes occupied habitat and shelters located at the edge of the population range that did not overlap with adults. No such pattern was observed in the slow worm. Our study indicates that intraspecific interactions affect the spatial ecology of squamates. Passive and active protection of habitat must include wide buffers to preserve the poorly detectable young fraction of the population.

Emergence and dispersal of snakes after syntopic hibernation

A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter) was studied. Seven snake species used this hibernating den, Malpoloninsignitus, Dolichophiscaspius, Platycepsnajadum, Elaphequatuorlineata, Telescopusfallax, Viperaammodytes and Xerotyphlopsvermicularis. The emergence of the snakes was related to the rise of daily temperatures. Malpoloninsignitus emerged from hibernation earlier in the spring than the other species, and most individuals were the first to leave the hibernaculum. There was a temporal segregation among the basking area in early spring, between the latter species and D.caspius, which were the two most abundant species. These two species also used the same area of the hibernaculum, in contrast to P.najadum and E.quatuorlineata, which used a different area. After spring dispersal, M.insignitus and D.caspius used the same microhabitats during the rest of the active period. The earlier emergence of M.insignitus (and earlier departure from the site) probably reduces the competition for basking sites. The early departure of the species may give advantage in the competition for optimal microhabitats with D.caspius.