The spatial and temporal aspects of the habitat suitability of the European souslik (Spermophilus... more The spatial and temporal aspects of the habitat suitability of the European souslik (Spermophilus citellus L.) in an area of Sredna Gora Mountain (Bulgaria) were studied. We used Landsat satellite imagery data to model changes in the habitat suitability of the species from 1985 to 2018. The obtained results demonstrate that the habitat suitability of the European souslik increased during the studied period, presumably due to raised temperatures and the accompanying drought during summertime, as well as the human-caused modifications in pasture livestock breeding. Based on statistical modelling, the employed procedure applies to long-term monitoring and assessment of the role of land cover change because of climate change and human activity on the habitat suitability of the European souslik. This approach can be useful for conservation planning.
The defensive behavior of two individuals of the Lesser blind mole rat, Nannospalax (superspecies... more The defensive behavior of two individuals of the Lesser blind mole rat, Nannospalax (superspecies) leucodon (Nordmann, 1840), was investigated. A characteristic defensive posture and two types of vocalization were recorded: teeth grinding and grunting, expressed by consecutive series of complex harsh calls, consisting of sequences of single very short (1.7 – 2.6 ms) phases (with maximum energy at about 9.8 KHz), accompanied by strong noise component. More research is needed to reveal the full vocal repertoire and behavioral characteristics of the species.
Morphological variation of two species of water shrews, Neomys anomalus (N=401) and N. fodiens (N... more Morphological variation of two species of water shrews, Neomys anomalus (N=401) and N. fodiens (N=192), from 13 areas in Bulgaria was studied by taking 66 measurements of skull, mandible and dentition. Univariate and multivariate analyses (Principal Component Analysis, PCA and Canonical Variate Analysis, CVA) were used to reveal patterns of variation, trying to separate the effect of physical factors, presented by altitudinal gradient, from the effect of the supposedly most important biotic factor, competition, expressed as character displacement/release. PCA revealed two general groups of characters. The first group reflects the differences between the two species. CVA distinguishes within this group two characters strictly related to species differences (the height of the upper incisive and the height of coronoid process) and one character (rostral length), affected by altitudinal gradient. The characters in the second group reflect the differences between allopatric and sympatric...
The spatial distribution of small mammals and their assemblages in the area of the Srebarna Manag... more The spatial distribution of small mammals and their assemblages in the area of the Srebarna Managed Nature Reserve were studied, using permanent pitfall traps. Classification and ordination analyses (TWINSPAN and PCA) reveal that the vegetation structure (development of the tree, shrub and herbaceous layers) and the substrate moisture are the most important factors, affecting the spatial distribution of the small mammal assemblages. Five assemblage types and 14 local assemblages were revealed, which were studied in respect to their structure and diversity. Four species groups were recognized and their environmental affiliations within the study region were described.
The morphometric variability of the skull and the lower jaw of 6 species of shrews (Croci-dura su... more The morphometric variability of the skull and the lower jaw of 6 species of shrews (Croci-dura suaveolens s. l., C. leucodon, Neomys anomalus, N. fodiens, Sorex minutus, and S. araneus) from Bulgaria, Romania, Hungary, and Austria was analyzed. The results from the PCA and the unsupervised model-based clustering showed that morphological geographic in-traspecific variation was clearly expressed in Crocidura suaveolens and C. leucodon, poorly pronounced in Neomys anomalus and N. fodiens, and almost missing in Sorex minutus and S. araneus. Our data provide a morphological confirmation of the recent molecular data, which indicate a division of both Crocidura species to western and eastern lineages. The geographical location of their boundaries was discussed.
Field data on the terrestrial mammalian fauna (Eulipotyphla, Lagomorpha, Rodentia, Carnivora, Art... more Field data on the terrestrial mammalian fauna (Eulipotyphla, Lagomorpha, Rodentia, Carnivora, Artiodactyla) of Lozen Мountain collected from 2005 untill 2019 were summarized. Several methods were used: live trapping, pitfall trapping, camera trapping, transects for signs (e.g. prints and scats), and visual observations. The investigation revealed relatively high species richness of the mammalian fauna in the area. The species composition of mammal associations in forested and open habitats, the conservation status and zoogeographic classification of the recorded species are presented. The distribution and habitat preferences of particular species (Neomys fodiens, Muscardinus avellanarius, Canis aureus, etc.) are discussed. The significance of the natural and the semi-natural habitats in Lozen Mountain for mammalian populations is considered. The main threats for the mammals and their habitats on the territory of Natura 2000 site “Lozenska planina” (BG0000165) are emphasized and reco...
The spatial and temporal aspects of the habitat suitability of the European Souslik (Spermophilus... more The spatial and temporal aspects of the habitat suitability of the European Souslik (Spermophilus citellus L.) in an area in Sredna Gora Mountain (Bulgaria) was investigated. Data from Landsat satellite imagery were used for modelling changes in the habitat suitability of the species from 1985 till 2018. Linear Regression Analysis showed that spectral bands represent not only the spatial heterogeneity of the landcover, but also the temporal changes of two climatic parameters – monthly temperature and rainfall amount. The obtained results show that the habitat suitability of the European Souslik increased during the studied period. The methodology used here based on statistical modelingis applicable to long-term monitoring and evaluation of the role of land cover change as a result of the human activity and the climate change on the habitat suitability of the European Souslik.
ABSTRACT The spatial distribution of small mammals and their assemblages in the area of the Sreba... more ABSTRACT The spatial distribution of small mammals and their assemblages in the area of the Srebarna Managed Nature Reserve were studied, using permanent pitfall traps. Classification and ordination analyses (TWINSPAN and PCA) reveal that the vegetation structure (development of the tree, shrub and herbaceous layers) and the substrate moisture are the most important factors, affecting the spatial distribution of the small mammal assemblages. Five assemblage types and 14 local assemblages were revealed, which were studied in respect to their structure and diversity. Four species groups were recognized and their environmental affiliations within the study region were described.
The morphological differences between sexes of six soricid species belonging to two subfamilies, ... more The morphological differences between sexes of six soricid species belonging to two subfamilies, Crocidurinae (Crocidura suaveolens and C. leucodon) and Soricinae (Neomys anomalus, N. fodiens, Sorex araneus and S. minutus), were studied on the basis of 39 cranial, mandibular and tooth measurements. Different patterns regarding sexual differences in size were recorded in the two subfamilies. The two whitetoothed shrew species exhibited clear male-biased sexual size differences, which were better expressed in C. suaveolens compared to C. leucodon as well as in Southeastern Europe compared to Central Europe. Conversely, red-toothed shrews did not display distinct sexual differences in size. In N. fodiens, N. anomalus, S. araneus and S. minutus, some measurements were larger in males, others were larger in females, while certain measurements did not differ between sexes. Furthermore, differences between samples of one species were observed. The characters that showed the most significant sex variations differed among the species. As a great overlap exists among the ranges of the measurements, it is more correct to speak of size differences between sexes rather than of a distinct sexual size dimorphism.
Morphological variation of two species of water shrews, Neomys anomalus (N=401) and N. fodiens (N... more Morphological variation of two species of water shrews, Neomys anomalus (N=401) and N. fodiens (N=192), from 13 areas in Bulgaria was studied by taking 66 measurements of skull, mandible and dentition. Univariate and multivariate analyses (Principal Component Analysis, PCA and Canonical Variate Analysis, CVA) were used to reveal patterns of variation, trying to separate the effect of physical factors, presented by altitudinal gradient, from the effect of the supposedly most important biotic factor, competition, expressed as character displacement/release. PCA revealed two general groups of characters. The fi rst group refl ects the differences between the two species. CVA distinguishes within this group two characters strictly related to species differences (the height of the upper incisive and the height of coronoid process) and one character (rostral length), affected by altitudinal gradient. The characters in the second group refl ect the differences between allopatric and sympatric populations of N. anomalus. The analysis of interspecifi c morphological distances confi rms this interpretation. The obtained results are consistent with the hypothesis that N. anomalus has undergone a character release where it is allopatric from N. fodiens.
The spatial and temporal aspects of the habitat suitability of the European souslik (Spermophilus... more The spatial and temporal aspects of the habitat suitability of the European souslik (Spermophilus citellus L.) in an area of Sredna Gora Mountain (Bulgaria) were studied. We used Landsat satellite imagery data to model changes in the habitat suitability of the species from 1985 to 2018. The obtained results demonstrate that the habitat suitability of the European souslik increased during the studied period, presumably due to raised temperatures and the accompanying drought during summertime, as well as the human-caused modifications in pasture livestock breeding. Based on statistical modelling, the employed procedure applies to long-term monitoring and assessment of the role of land cover change because of climate change and human activity on the habitat suitability of the European souslik. This approach can be useful for conservation planning.
The defensive behavior of two individuals of the Lesser blind mole rat, Nannospalax (superspecies... more The defensive behavior of two individuals of the Lesser blind mole rat, Nannospalax (superspecies) leucodon (Nordmann, 1840), was investigated. A characteristic defensive posture and two types of vocalization were recorded: teeth grinding and grunting, expressed by consecutive series of complex harsh calls, consisting of sequences of single very short (1.7 – 2.6 ms) phases (with maximum energy at about 9.8 KHz), accompanied by strong noise component. More research is needed to reveal the full vocal repertoire and behavioral characteristics of the species.
Morphological variation of two species of water shrews, Neomys anomalus (N=401) and N. fodiens (N... more Morphological variation of two species of water shrews, Neomys anomalus (N=401) and N. fodiens (N=192), from 13 areas in Bulgaria was studied by taking 66 measurements of skull, mandible and dentition. Univariate and multivariate analyses (Principal Component Analysis, PCA and Canonical Variate Analysis, CVA) were used to reveal patterns of variation, trying to separate the effect of physical factors, presented by altitudinal gradient, from the effect of the supposedly most important biotic factor, competition, expressed as character displacement/release. PCA revealed two general groups of characters. The first group reflects the differences between the two species. CVA distinguishes within this group two characters strictly related to species differences (the height of the upper incisive and the height of coronoid process) and one character (rostral length), affected by altitudinal gradient. The characters in the second group reflect the differences between allopatric and sympatric...
The spatial distribution of small mammals and their assemblages in the area of the Srebarna Manag... more The spatial distribution of small mammals and their assemblages in the area of the Srebarna Managed Nature Reserve were studied, using permanent pitfall traps. Classification and ordination analyses (TWINSPAN and PCA) reveal that the vegetation structure (development of the tree, shrub and herbaceous layers) and the substrate moisture are the most important factors, affecting the spatial distribution of the small mammal assemblages. Five assemblage types and 14 local assemblages were revealed, which were studied in respect to their structure and diversity. Four species groups were recognized and their environmental affiliations within the study region were described.
The morphometric variability of the skull and the lower jaw of 6 species of shrews (Croci-dura su... more The morphometric variability of the skull and the lower jaw of 6 species of shrews (Croci-dura suaveolens s. l., C. leucodon, Neomys anomalus, N. fodiens, Sorex minutus, and S. araneus) from Bulgaria, Romania, Hungary, and Austria was analyzed. The results from the PCA and the unsupervised model-based clustering showed that morphological geographic in-traspecific variation was clearly expressed in Crocidura suaveolens and C. leucodon, poorly pronounced in Neomys anomalus and N. fodiens, and almost missing in Sorex minutus and S. araneus. Our data provide a morphological confirmation of the recent molecular data, which indicate a division of both Crocidura species to western and eastern lineages. The geographical location of their boundaries was discussed.
Field data on the terrestrial mammalian fauna (Eulipotyphla, Lagomorpha, Rodentia, Carnivora, Art... more Field data on the terrestrial mammalian fauna (Eulipotyphla, Lagomorpha, Rodentia, Carnivora, Artiodactyla) of Lozen Мountain collected from 2005 untill 2019 were summarized. Several methods were used: live trapping, pitfall trapping, camera trapping, transects for signs (e.g. prints and scats), and visual observations. The investigation revealed relatively high species richness of the mammalian fauna in the area. The species composition of mammal associations in forested and open habitats, the conservation status and zoogeographic classification of the recorded species are presented. The distribution and habitat preferences of particular species (Neomys fodiens, Muscardinus avellanarius, Canis aureus, etc.) are discussed. The significance of the natural and the semi-natural habitats in Lozen Mountain for mammalian populations is considered. The main threats for the mammals and their habitats on the territory of Natura 2000 site “Lozenska planina” (BG0000165) are emphasized and reco...
The spatial and temporal aspects of the habitat suitability of the European Souslik (Spermophilus... more The spatial and temporal aspects of the habitat suitability of the European Souslik (Spermophilus citellus L.) in an area in Sredna Gora Mountain (Bulgaria) was investigated. Data from Landsat satellite imagery were used for modelling changes in the habitat suitability of the species from 1985 till 2018. Linear Regression Analysis showed that spectral bands represent not only the spatial heterogeneity of the landcover, but also the temporal changes of two climatic parameters – monthly temperature and rainfall amount. The obtained results show that the habitat suitability of the European Souslik increased during the studied period. The methodology used here based on statistical modelingis applicable to long-term monitoring and evaluation of the role of land cover change as a result of the human activity and the climate change on the habitat suitability of the European Souslik.
ABSTRACT The spatial distribution of small mammals and their assemblages in the area of the Sreba... more ABSTRACT The spatial distribution of small mammals and their assemblages in the area of the Srebarna Managed Nature Reserve were studied, using permanent pitfall traps. Classification and ordination analyses (TWINSPAN and PCA) reveal that the vegetation structure (development of the tree, shrub and herbaceous layers) and the substrate moisture are the most important factors, affecting the spatial distribution of the small mammal assemblages. Five assemblage types and 14 local assemblages were revealed, which were studied in respect to their structure and diversity. Four species groups were recognized and their environmental affiliations within the study region were described.
The morphological differences between sexes of six soricid species belonging to two subfamilies, ... more The morphological differences between sexes of six soricid species belonging to two subfamilies, Crocidurinae (Crocidura suaveolens and C. leucodon) and Soricinae (Neomys anomalus, N. fodiens, Sorex araneus and S. minutus), were studied on the basis of 39 cranial, mandibular and tooth measurements. Different patterns regarding sexual differences in size were recorded in the two subfamilies. The two whitetoothed shrew species exhibited clear male-biased sexual size differences, which were better expressed in C. suaveolens compared to C. leucodon as well as in Southeastern Europe compared to Central Europe. Conversely, red-toothed shrews did not display distinct sexual differences in size. In N. fodiens, N. anomalus, S. araneus and S. minutus, some measurements were larger in males, others were larger in females, while certain measurements did not differ between sexes. Furthermore, differences between samples of one species were observed. The characters that showed the most significant sex variations differed among the species. As a great overlap exists among the ranges of the measurements, it is more correct to speak of size differences between sexes rather than of a distinct sexual size dimorphism.
Morphological variation of two species of water shrews, Neomys anomalus (N=401) and N. fodiens (N... more Morphological variation of two species of water shrews, Neomys anomalus (N=401) and N. fodiens (N=192), from 13 areas in Bulgaria was studied by taking 66 measurements of skull, mandible and dentition. Univariate and multivariate analyses (Principal Component Analysis, PCA and Canonical Variate Analysis, CVA) were used to reveal patterns of variation, trying to separate the effect of physical factors, presented by altitudinal gradient, from the effect of the supposedly most important biotic factor, competition, expressed as character displacement/release. PCA revealed two general groups of characters. The fi rst group refl ects the differences between the two species. CVA distinguishes within this group two characters strictly related to species differences (the height of the upper incisive and the height of coronoid process) and one character (rostral length), affected by altitudinal gradient. The characters in the second group refl ect the differences between allopatric and sympatric populations of N. anomalus. The analysis of interspecifi c morphological distances confi rms this interpretation. The obtained results are consistent with the hypothesis that N. anomalus has undergone a character release where it is allopatric from N. fodiens.
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Papers by Sirma Zidarova
(Crocidura suaveolens and C. leucodon) and Soricinae (Neomys anomalus, N. fodiens, Sorex
araneus and S. minutus), were studied on the basis of 39 cranial, mandibular and tooth measurements. Different
patterns regarding sexual differences in size were recorded in the two subfamilies. The two whitetoothed
shrew species exhibited clear male-biased sexual size differences, which were better expressed in
C. suaveolens compared to C. leucodon as well as in Southeastern Europe compared to Central Europe.
Conversely, red-toothed shrews did not display distinct sexual differences in size. In N. fodiens, N. anomalus,
S. araneus and S. minutus, some measurements were larger in males, others were larger in females,
while certain measurements did not differ between sexes. Furthermore, differences between samples of
one species were observed. The characters that showed the most significant sex variations differed among
the species. As a great overlap exists among the ranges of the measurements, it is more correct to speak of
size differences between sexes rather than of a distinct sexual size dimorphism.
(Crocidura suaveolens and C. leucodon) and Soricinae (Neomys anomalus, N. fodiens, Sorex
araneus and S. minutus), were studied on the basis of 39 cranial, mandibular and tooth measurements. Different
patterns regarding sexual differences in size were recorded in the two subfamilies. The two whitetoothed
shrew species exhibited clear male-biased sexual size differences, which were better expressed in
C. suaveolens compared to C. leucodon as well as in Southeastern Europe compared to Central Europe.
Conversely, red-toothed shrews did not display distinct sexual differences in size. In N. fodiens, N. anomalus,
S. araneus and S. minutus, some measurements were larger in males, others were larger in females,
while certain measurements did not differ between sexes. Furthermore, differences between samples of
one species were observed. The characters that showed the most significant sex variations differed among
the species. As a great overlap exists among the ranges of the measurements, it is more correct to speak of
size differences between sexes rather than of a distinct sexual size dimorphism.