The Danube River is the second longest river in Europe; it flows through ten countries and is 2,850 km in length. In its lower stretches it passes through large lowlands and remains an almost intact ...natural ecosystem. For 470 km, the river acts as a border between Bulgaria and Romania and provides a refuge for very rich, yet insufficiently studied, biodiversity. The flora and fauna of this area, not far from the Danube Delta biosphere reserve, and its environmental importance are the topics of this book. The book is comprised of 12 separate scientific articles (chapters) that each contain specialized information about key organism groups forming the typical Lower Danube ecosystem. Vertebrate fauna of the study region includes 392 species out of which 83 species are fishes, 19 are amphibians, 15 are reptiles, 201 are birds, and 74 are mammals. Birds are presented in three separate articles with a focus on heron colonies, water birds in the marshlands, and diurnal raptors. Among the invertebrates, several key groups which are comparatively well-studied, are presented, including mollusks; dragonflies and damselflies (in overall 52 species); dipterans of suborder Nematocera (153 species); mayflies (52 species); stoneflies (3 species); and caddisflies (49 species), butterflies (153 species). An article about habitats and typical plants of the Danube plain is also included. The articles all contain information on the status, distribution and ecology of the study's organism groups, and the threats they face. Overall numbers and population trends of some of the presented taxa are also included; 281 maps, 29 graphs, 21 tables and 49 photographs help illustrate various aspects of the collected data. The authors of the articles are well-known and experienced experts on specific organism groups, working mainly out of two institutions of the Bulgarian Academy of Sciences: the National History Museum (Sofia) and the Institute of Biodiversity and Ecosystem Research (Sofia).
Blood parasites have been studied intensely in many families of avian hosts, but corvids, a particularly cosmopolitan family, remain underexplored. Haemosporidian parasites of the common raven ...(Corvus corax) have not been studied, although it is the largest, most adaptable, and widespread corvid. Genetic sequence data from parasites of ravens can enhance the understanding of speciation patterns and specificity of haemosporidian parasites in corvids, and shed light how these hosts cope with parasite pressure.
A baited cage trap was used to catch 86 ravens and a nested PCR protocol was used to amplify a 479 bp fragment of the haemosporidian cytochrome b gene from the samples. The obtained sequences were compared with the MalAvi database of all published haemosporidian lineages and a phylogenetic tree including all detected raven parasites was constructed. An examination of blood smears was performed for assessment of infection intensity.
Twenty blood parasite lineages were recovered from ravens caught in a wild population in Bulgaria. The prevalence of generalist Plasmodium lineages was 49%, and the prevalence of Leucocytozoon lineages was 31%. Out of 13 detected Leucocytozoon lineages six were known from different corvids, while seven others seem to be specific to ravens. A phylogenetic reconstruction suggests that Leucocytozoon lineages of ravens and other corvids are not monophyletic, with some groups appearing closely related to parasites of other host families.
Several different, morphologically cryptic groups of Leucocytozoon parasites appear to infect corvids. Ravens harbour both generalist corvid Leucocytozoon as well as apparently species-specific lineages. The extraordinary breeding ecology and scavenging lifestyle possibly allow ravens to evade vectors and have relatively low blood parasite prevalence compared to other corvids.
Studying current and future geographic distribution is essential for conserving endangered species such as the Boreal Owl and Eurasian Pygmy Owl. The main aim of this study was to determine the ...potential distribution of both species in the Balkan Peninsula by using spatial distribution models (SDMs) in MaxEnt. We used data from field surveys, the scientific and grey literature, and an online database. We considered the current time and two future periods, 2041-2060 and 2061-2080. For future periods, we included different climate scenarios (SSP 126, 245, 370, and 585) in studying the potential geographic distribution of both species. We identified two types of potential future refugia for species: in situ and ex situ. Our study shows the highly suitable area for the Boreal Owl increased during the 2041-2060 period compared with the current area in all scenarios, except in SSP 585. However, during the 2061-2080 period, the highly suitable areas contracted. For the Eurasian Pygmy Owl, highly suitable areas decreased during 2041-2060, but during the 2061-2080 period, it was larger than the current area. Our study is of importance for conservation and preserving areas of potential distribution and refugia for Boreal and Eurasian Pygmy Owls in the face of climate change.
Blood parasites of migrating yellow wagtails of two subspecies—
Motacilla flava feldegg
and
Motacilla flava flava
—were studied on a sample of 473 birds caught in spring and autumn periods in ...Bulgaria. We controlled eight “migration waves” (flocks captured in different evenings) of yellow wagtails for four parameters—average body mass, average fat level, average wing length, and average prevalence of different hematozoan species. Gametocytes or meronts of a total of six species of hematozoa belonging to three genera were identified—
Haemoproteus motacillae
,
Haemoproteus anthi
,
Plasmodium relictum
,
Plasmodium subpraecox
,
Plasmodium cathemerium
, and
Tryponosoma avium
. Mixed infections were detected in 31 cases, of which 14 were of
H. anthi
/
H. motacillae
type. Parasite species composition was similar in the two studied subspecies of
M. flava
. We did not find any significant differences in the overall infection prevalence or number of infecting parasites between
M. f. flava
and
M. f. feldegg
. Parasite prevalence and the number of co-infecting parasites in spring were much higher than in fall. Season had a strong influence on the prevalence of
H. anthi
and
H. motacillae
, and for both, there was a marginally significant interaction between subspecies and season, but not a season-independent influence of subspecies. Males of
M. f. feldegg
had a significantly higher overall blood parasite prevalence and prevalence of
H. anthi
than females. Sex-related differences in the prevalence of other parasites were not significant. Migration waves of yellow wagtails differed in overall infection status and in
H. motacillae
prevalence, but not for
H. anthi
prevalence. We also found significant differences in fat score, weight, and wing length between the studied migration waves of the yellow wagtails. Fat scores of birds infected with different hematozoa were lower compared with those of the non-infected birds. This only marginally was true for body weight and was not the case for wing length. Overall, infected birds were in worse condition (estimated as the residual weight after regression with wing length) compared with the non-infected birds, but after controlling for seasonal effects, the differences in condition appeared to be due to migration season and did not significantly differ between infected and non-infected birds caught in the same season.
Hunting behavior was studied in a small breeding population of Red-footed Falcons in SE-Bulgaria and in a transitory migrants of the same species. A total of seven types of hunting strategies were ...performed by the Red-footed Falcons which can be rapidly switched from one to another in relation to the available type of prey, the speed and direction of the wind. It was recorded that the hovering series were longer in calm weather (wind speed < 2 m/s) and in strong winds (over 5 m/s) than in moderate winds (2 – 5 m/s). Difference was found in the mean length of the hovering series between the migrating and local breeding Red-footed Falcons. The hunting success of the finished attacks of the Redfooted Falcons was in overall 59.6 %.
Species composition and prevalence of the blood parasites of three migratory Acrocephalus species of warblers (Acrocephalus arundinaceus, Acrocephalus scirpaceus and Acrocephalus schoenobaenus) were ...studied during spring period in Bulgaria. For each of the studied species, we compared the parasite fauna during their spring migration at three study sites in search of infection patterns in time and space. Spatial differences were registered in the blood parasites and their prevalence for two of the studied species--A. arundinaceus and A. scirpaceus, whereas for the third one--A. schoenobaenus, there were no significant differences. The parasite species Haemoproteus belopolskyi was present in migrating A. arundinaceus only at Kalimok station, but not at the other two sampling locations. Plasmodium prevalence in A. arundinaceus migrating through Kalimok was also different between years. A decrease of H. belopolskyi prevalence was detected for A. schoenobaenus at Petarch during the spring of 2006. On the contrary, Plasmodium (Haemamoeba) sp. infections of the same bird species increased during the spring period. The differences found between sites could be explained with the different origin of the migrants at different migration stopover points. Climatic conditions and vector abundance in the zones of origin are probable reasons for the observed differences between years.
PDF
