Papers by Borislav Naumov
Herpetozoa
Different snake species may be active at various times of the day. In Europe, most snake species ... more Different snake species may be active at various times of the day. In Europe, most snake species are predominantly diurnal, but about a third are partially or principally crepuscular and/or nocturnal. Here, we report the first instance of multiple in situ observations of the crepuscular and nocturnal activity of V. ammodytes in Bulgaria. Overall, usually as a result of general herpetological surveys and chance observations between 2001–2020, we recorded crepuscular/nocturnal activity of twenty-seven individuals from both sexes and all age classes (juvenile to adult), observed from April to September, following warm (maximum daily Tair = 20–28 °C) and hot (Tair > 28 °C) days. These records represent less than 1.5% of all our personal viper observations. However, given that our observations occurred throughout the country, within five different climatic zones, we hypothesise that nocturnal activity of V. ammodytes is more common than previously reported.
Molecules
Snakes rely heavily on chemical cues when foraging, searching for mates, etc. Snakes’ sex attract... more Snakes rely heavily on chemical cues when foraging, searching for mates, etc. Snakes’ sex attractiveness pheromones comprise mainly heavy, semi-volatile compounds such as ketones. Here we investigated the composition of skin secretions of adult Vipera ammodytes (Linnaeus, 1758) individuals. The samples were analyzed by gas chromatography/mass spectrometry and the identification of the compounds was performed using commercial mass spectral libraries and retention times. The relative concentrations of all detected compounds were tested for significant differences between (1) male vs. female live individuals, (2) shed skin vs. live individuals, and (3) pre-reproductive vs. reproductive live individuals. We detected fifty-nine compounds of which six were ketones. Two ketones (2-pentacosanone and 2-heptacosanone) were present in many of the samples and thus may have an important role in the V. ammodytes chemical communication. We did not find significant differences between the relative ...
ARPHA Conference Abstracts
In a recently published paper (Popgeorgiev et al. 2019), we compiled for the first time published... more In a recently published paper (Popgeorgiev et al. 2019), we compiled for the first time published and unpublished data on localities of the herpetofaunal species observed up to ca. 10 km south of the Bulgarian Danube River. Overall, we identified 687 published records belonging to 62 cells of the 10×10 km MGRS grid. Another 1918 records with real coordinates of our unpublished data from the past ca. 13 years belong to 1269 cells of the 1×1 MGRS grid. As a result, 34 native species – 15 amphibians (4 salamanders and 11 frogs) and 19 reptiles (1 turtle, 2 tortoises, 8 lizards and 8 snakes), and one invasive turtle, have been recorded; further species findings are unlikely. This study further identifies areas that are under-sampled and species such as Pelophylax lessonae that are cryptic. Our data are especially relevant concerning the high economic incentives to change the hydrology of the Danube, which will likely negatively impact the biodiversity along the river and its surrounding.
ARPHA Conference Abstracts
The Viviparous lizard Zootoca vivipara (Lichtenstein, 1823) is widespread across Eurasia, but in ... more The Viviparous lizard Zootoca vivipara (Lichtenstein, 1823) is widespread across Eurasia, but in Bulgaria it is considered a glacial relict, restricted to the high mountains. In spite of its wide distribution, there is still lack of knowledge on its dietary habits, especially from the southern part of the range. In order to shed light on its diet, we conducted а study in three mountain sites in Bulgaria (Vitosha, Rila and Stara Planina Mtns.). They were visited in 2016 and 2017 during the lizard's active season (May–September); 343 Viviparous lizards were captured by hand and measured and weighed. To investigate the food preferences, we adopted a non-invasive method, obtaining faecal samples, which were then analysed under a stereoscopic microscope. A total of 290 faecal samples that could be assigned to individual specimens with determined age and sex were collected. We calculated the relative abundance and occurrence of each prey category. Data were compared by sex and age cla...
Herpetozoa
A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter... more 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 de...
A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter... more A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter) was studied. Seven snake species used this hibernating den, Malpolon insignitus, Dolichophis caspius, Platyceps najadum, Elaphe quatuorlineata, Telescopus fallax, Vipera ammodytes and Xerotyphlops vermicularis. The emergence of the snakes was related to the rise of daily temperatures. Malpolon insignitus 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.
A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter... more A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter) was studied. Seven snake species used this hibernating den, Malpolon insignitus, Dolichophis caspius, Platyceps najadum, Elaphe quatuorlineata, Telescopus fallax, Vipera ammodytes and Xerotyphlops vermicularis. The emergence of the snakes was related to the rise of daily temperatures. Malpolon insignitus 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.
A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter... more A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter) was studied. Seven snake species used this hibernating den, Malpolon insignitus, Dolichophis caspius, Platyceps najadum, Elaphe quatuorlineata, Telescopus fallax, Vipera ammodytes and Xerotyphlops vermicularis. The emergence of the snakes was related to the rise of daily temperatures. Malpolon insignitus 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.
A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter... more A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter) was studied. Seven snake species used this hibernating den, Malpolon insignitus, Dolichophis caspius, Platyceps najadum, Elaphe quatuorlineata, Telescopus fallax, Vipera ammodytes and Xerotyphlops vermicularis. The emergence of the snakes was related to the rise of daily temperatures. Malpolon insignitus 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.
A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter... more A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter) was studied. Seven snake species used this hibernating den, Malpolon insignitus, Dolichophis caspius, Platyceps najadum, Elaphe quatuorlineata, Telescopus fallax, Vipera ammodytes and Xerotyphlops vermicularis. The emergence of the snakes was related to the rise of daily temperatures. Malpolon insignitus 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.
Ecological Questions
Increasing urbanisation in recent decades has subjected many species and their populations to the... more Increasing urbanisation in recent decades has subjected many species and their populations to the influence of anthropogenic noise generated by human technologies. Noise pollution can negatively affect acoustic communication in representatives of different taxa and frogs, as the most vocally active amphibians, are especially vulnerable to such adverse effects. In the present study, we tested the hypothesis that anthropogenic noise could alter the mating call parameters in the European treefrog. The two chosen study sites were in the same geographic area and had similar characteristics except for the presence of anthropogenic noise source. Recordings demonstrated significant differences in most of the studied parameters, suggesting that treefrogs are able to alter their calls and communicate successfully in moderate levels of anthropogenic noise.
Amphibia-Reptilia
The ‘smooth newt’, the taxon traditionally referred to as Lissotriton vulgaris, consists of multi... more The ‘smooth newt’, the taxon traditionally referred to as Lissotriton vulgaris, consists of multiple morphologically distinct taxa. Given the uncertainty concerning the validity and rank of these taxa, L. vulgaris sensu lato has often been treated as a single, polytypic species. A recent study, driven by genetic data, proposed to recognize five species, L. graecus, L. kosswigi, L. lantzi, L. schmidtleri and a more restricted L. vulgaris. The Carpathian newt L. montandoni was confirmed to be a closely related sister species. We propose to refer to this collective of six Lissotriton species as the smooth newt or Lissotriton vulgaris species complex. Guided by comprehensive genomic data from throughout the range of the smooth newt species complex we 1) delineate the distribution ranges, 2) provide a distribution database, and 3) produce distribution maps according to the format of the New Atlas of Amphibians and Reptiles of Europe, for the six constituent species. This allows us to 4) ...
PeerJ, 2016
A strongly ossified and rigid skull roof, which prevents parietal kinesis, has been reported for ... more A strongly ossified and rigid skull roof, which prevents parietal kinesis, has been reported for the adults of all amphibian clades. Our μ-CT investigations revealed that the Buresch’s newt (Triturus ivanbureschi) possess a peculiar cranial construction. In addition to the typical amphibian pleurokinetic articulation between skull roof and palatoquadrate associated structures, we found flexible connections between nasals and frontals (prokinesis), vomer and parasphenoid (palatokinesis), and between frontals and parietals (mesokinesis). This is the first description of mesokinesis in urodelans. The construction of the skull in the Buresch’s newts also indicates the presence of an articulation between parietals and the exocipitals, discussed as a possible kind of metakinesis. The specific combination of pleuro-, pro-, meso-, palato-, and metakinetic skull articulations indicate to a new kind of kinetic systems unknown for urodelans to this date. We discuss the possible neotenic origin...
A record of Triturus macedonicus (Karaman, 1922) in Slavyanka Mt. (SW Bulgaria) from June 2007 is... more A record of Triturus macedonicus (Karaman, 1922) in Slavyanka Mt. (SW Bulgaria) from June 2007 is announced. This is a new species for Bulgarian fauna, and the locality is the easternmost for the species in general. A short description of the habitat and morphology are given.
Biotechnology & Biotechnological Equipment, 2010
Protected Area "Besaparski ridove" in southwestern Bulgaria, based on a 2×2 km UTM grid. Between ... more Protected Area "Besaparski ridove" in southwestern Bulgaria, based on a 2×2 km UTM grid. Between 1998 and 2008, we identified 24 species, and failed to verify the literature data only for a fossorial boa, Eryx jaculus. We documented five new amphibian species for the region (Salamandra salamandra, Triturus karelinii, Bombina variegata, Bufo bufo, Rana dalmatina, and R. graeca) and four species of reptiles (Testudo graeca, T. hermanni, Ablepharus kitaibelii, and Zamenis longissimus). The least common amphibians in the protected area were S. salamandra, R. graeca, and T. karelinii (number of squares in which these species are present from the total, A = 1.85%) and the most common were Pelophylax ridibundus (A = 35.19%), B. bufo (A = 20.37%), and Epidalea viridis (A = 18.52%). The least common reptiles were T. graeca, T. hermanni, Z. longissimus, Platyceps najadum (A = 1.85%) and A. kitaibelii and E. jaculus (A = 3.7%). The most common reptiles were Podarcis tauricus (A = 44.44%), Lacerta trilineata (A = 42.59%), and L. viridis (A = 29.63%).
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Papers by Borislav Naumov