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The Common wall lizard (Podarcis muralis) has the largest range among the genus Podarcis. Although there are a number of studies on its diet, data on regional level remains insufficient, particularly from a purely ecological perspective. We investigated 194 individual faecal samples of P. muralis obtained from two localities in western Bulgaria with the aim of clarifying the composition of the trophic spectrum of the species, as well as the intra-population characteristics in terms of age and sex. In one study site, we compared the realized trophic niche (prey items from the faecal pellets) with the fundamental (invertebrates collected via pit-fall traps exposure). We confirmed that P. muralis is an opportunist in terms of feeding and has a very wide trophic spectrum including several taxa, which have not been reported until now as a part of the species' diet. We revealed differences in feeding behavior between subadults and adults, as well as between males and females. Adults have higher diversity in the food spectrum compared to subadults. According to sexes, females have more varied diet. We also report for the first time for the species six cases of keratophagy. Also, we identified a relatively frequent occurrence of saurophagy (n = 16), including in females and subadults, for which this phenomenon has not been recorded so far. [ABSTRACT FROM AUTHOR]

Studies on the gut microbiome of free-living reptiles in Europe are generally fragmentary and still missing in Bulgaria. We aimed to identify and compare the fecal microbiota profiles of five syntopic lizard species from three families: the European green lizard (Lacerta viridis), the common wall lizard (Podarcis muralis), the meadow lizard (Darevskia praticola) (Lacertidae), the European snake-eyed skink (Ablepharus kitaibelii) (Scincidae), and the European slow worm (Anguis fragilis) (Anguidae), which coinhabit a low mountainous area in the western part of the country. A high-throughput sequencing of the hypervariable V3-V4 region of the 16S rRNA gene, performed on the Illumina HiSeq2500 platform, was used. The core microbiota of lizard hosts seems to be species-specific. A dynamic phyla proportion between hosts was found. The richest alpha diversity was observed in D. praticola, and the lowest alpha diversity was observed in P. muralis and A. fragilis. Within the three lacertids, the microbiota of D. praticola and L. viridis were more closely related to each other than they were to those of P. muralis. Sharing a largely common trophic resource (all species except A. fragilis are mainly insectivorous) was not an indication of similarity in their gut microbial communities. [ABSTRACT FROM AUTHOR]

Thermal ecology is critical for the study of the biology of every living species. Accordingly, body temperature affects the performance and fitness of animals. In the particular case of ectotherms, this effect is further reinforced since they rely on environmental conditions for heat adjustment. Current air and substrate temperatures are among the crucial sources of regulation for their body heat. In the case of lizards, various behavioral techniques are employed to insure their thermoregulation and therefore survival. The aim of the present study is to identify the basic thermal preferences of Lacerta agilis bosnica, including possible age and sex related variations. This lacertid subspecies is endemic to the high mountains across the Balkan Peninsula and limited between 1100 and 2200 m above sea level. Our results revealed highest body temperature of 35.9°C and lowest - of 19.5°C both measured in adult females. We calculated the average thermoadaptation index (Ti) of 1.27 for all individuals. Furthermore, the positive correlations of lizard body temperature (Tb) compared to air (Ta) and to substrate (Ts) temperatures were highest in immature males, while lowest - in adult males. We found statistically significant differences between the age/sex groups within Tb and Ta. Regarding Ts and Ti, the tests did not show significant differences between the groups. We concluded that L. agilis bosnica is a taxon adapted to low ambient temperatures. With this discovery we contributed to the exploration of the understudied subspecies Lacerta agilis bosnica. [ABSTRACT FROM AUTHOR]

There is a lack of information for potential winter activity of the snake-eyed lizard Ophisops elegans in Europe, where it has a limited distribution. To test the hypothesis that this species can be active during the winter months, two locations in Bulgaria were chosen. The visits were conducted in January, February and December 2022 near the village of Meden Buk and in December 2022 above the village of Mezek. A total of 19 individuals of O. elegans were recorded. In addition, we confirmed foraging behaviour based on faecal sample collection. To our knowledge, this is the northernmost record of winter activity in the snake-eyed lizard and the first consecutive observation of year-round activity for this species in Europe. [ABSTRACT FROM AUTHOR]

The distribution and occurrence of a species in its habitat are inevitably linked to its ecology. To successfully monitor and protect species, it is important to investigate which species-specific factors influence its interactions with the environment. In this study, we focus on patterns in habitat use of the Sand Lizard (Lacerta agilis). Differences in seasonal as well as sex and size class-dependent habitat use have been reported from the edges of this species' range. To verify such trends in the core area of its distribution, we analyzed the habitat factors weather, microclimate, microhabitat structures, and time dependence, which may have an impact on the use of space of the Sand Lizard. Using generalized linear models, hypervolumes, density estimations, and Chi-squared tests, we found that the movement patterns of individuals can neither be described by time differences, climatic conditions, or habitat composition, nor do they show habitat- or weather-related differences of movement between sexes or size. Here we demonstrate that in the case of a population from the core of this species' distribution area in the Dellbrücker Heide (Germany), habitat use is solely influenced to a low degree by differences related to the ontogeny of Sand Lizards and does not depend on any of the other evaluated factors. These results are in enormous contrast to findings in populations from the periphery of their distribution, i.e., the United Kingdom, Latvia, Romania, Bulgaria, and the Pyrenees. This implies that seasonal habitat shifts are more extreme at the edges of the range of L. agilis, serving to compensate deteriorating habitat conditions in the periphery. [ABSTRACT FROM AUTHOR]

The Meadow lizard (Darevskia praticola s.l.) is one of the more poorly-studied lizard species in Europe, and no detailed data on its diet is available. We investigated a total of 180 faecal samples of D. praticola s.l. from two locations in Bulgaria, and conducted a comparison between sex and age groups (adult males, adult females, and immatures). In addition, the correlations between the consumed prey and the available resources were also analysed. Food selectivity was analysed by comparing the faecal samples with pit-fall trap samples on the basis of abundance of prey items from particular operational taxonomic units (OTUs). Results indicate that the diet of the Meadow lizard contains mainly arthropods (insects and spiders) and the most abundant prey items belong to Araneae, Auchenorrhyncha, and Coleoptera. According to the used electivity indices none of the OTUs are highly preferred by D. praticola s.l., but Formicidae are the most avoided OTU for all sex/age groups. Differences in food preferences can be found between adults and immatures, while differences among males and females seem to be insignificant. The lack of clear differentiation between males and females could be a result of their similar size and locomotor ability. In conclusion, our results reveal that Darevskia praticola s.l. is a generalist and it shows no food specialization due to its narrow spatial niche. [ABSTRACT FROM AUTHOR]

The lizards of Bulgaria and their habitats are presented in text and pictures. During several trips the authors were able to find nine of the ten species of the family Lacertidae occurring there. [ABSTRACT FROM AUTHOR]

We present unpublished data on the diet of three lizards (Lacerta trilineata, Lacerta agilis and Podarcis tauricus) from the Lacertidae family, collected in 1974 in few localities in Southern Bulgaria. The analyzed data showed that the insects (Insecta) are the most numerous and the most frequently met food component and among the non-insect components the spiders and isopods are slightly predominating. The largest niche breadth was recorded in Podarcis tauricus (6.135), followed by Lacerta trilineata (5.263) and Lacerta agilis (4.132). All three studied lacertid species are classified as opportunistic general feeders (polyphages), which may show slight preference towards beetles, ants or spiders, depending on the occupied habitat or the season. [ABSTRACT FROM AUTHOR]

Although the Viviparous lizard (Zootoca vivipara) is one of the most successful lizard species and is widespread across Eurasia, data on its dietary habits are still lacking, especially from the southern part of its range. In order to shed light on its diet, we conducted study in three high mountains in Bulgaria, which represent separate "patches" from the range of Z. vivipara in the country. To investigate the food preferences, we adopted a non-invasive method using faecal samples and a total of 290 faecal samples that could be assigned to individual specimens with determined age and sex were collected. A total of 19 prey categories were detected and the number of categories per each study site varied between 16 and 18, which indicates opportunistic feeding habits. The most preferred prey types were Auchenorrhyncha (Order Hemiptera) and Araneae, while Formicidae and Opilones, abundant in the field, were avoided. Two physical characteristics of the prey, hardness and evasiveness, were analysed. In respect to hardness, Z. vivipara choose more often hard prey, and in respect to evasiveness, sedentary prey was consumed more often, hence we could suggest that Z. vivipara is an active forager. Statistically significant differences between immatures and adults were found as adults showed more diverse diet. No such differences between sexes were detected. Two cases of (partial) cannibalism and many cases of keratophagy (in 9% of the faecal pellets) were detected. [ABSTRACT FROM AUTHOR]