Spring migrations of the Whooper swan and Bewick's swan were studied on a farm-land near the town of Olonets during 1997 - 2017. Usually the majority of swans crossed the territory of the agricultural landscape in transit, and only a small portion of the birds stayed on it for feeding for 1 - 2 days. In 2017, swans formed a mass migration stopover on the fields, 340 to 1,328 individuals were counted on it for 11 days, whose majority (about 90%) were Bewick's swans. It was established that such a high concentration of swans in the fields was a result of a unfavorable ecological situation in the region at the beginning of their mass migration. The places of traditional migration stopovers in shallow waters of the Ladoga lake were closed by floating ice, and unusually cold weather of the second half of April and ice-covered water bodies in the Northern part of the migratory route hindered the migration of birds to their breeding grounds. In the current situation, the swans were forced to look for new places of feeding, and concentrated in the most favorable (for this purpose) grounds of the agricultural landscape.

Chromosomal (routine, C-banding) and molecular (cytb) data for Sicista of the betulina group from the northern (Valdai National Park), central (the main watershed of East European Plain) and southeast (Upper Volga Basin) parts of Valdai and, for comparison, from the Moscow and Central Chernozem regions are presented and generalized. The birch mice from Valdai and the Moscow area belonging to the 32-chromosomal S. betulina, and that from the Central Chernozem area belonging to S. strandi (2n = 44) are confirmed. Birch mice were collected in various biotopes: individuals from Valdai National Park were sought for in coniferous forests with nemoral covering, other groups of S. betulina were sought for in mixed forests, and S. strandi were sought for in a forest-steppe. Priority chromosomal (C-banding) and molecular (cytb) data were obtained to indicate an originality of the S. betulina population from Valdai National Park differing in the studied genetic signs from other selections of the species from Valdai and the Moscow area and from S. strandi as well. Evolutionary and ecological aspects of the results obtained are discussed.

Tengmalm’s Owl (Aegolius funereus caucasicus But.) inhabits dark coniferous, pine and deciduous forests in the mountains of the North Caucasus from the City of Tuapse in the west to the Inner Dagestan in the east, rising to pine forests to a height of 1,900 - 2,000 m above sea level. During its winter wanderings it occasionally occurs in the foothills, but almost does not go out to the piedmont plains. Winter records in the steppe regions of Ciscaucasia may refer to nomadic specimens of a nominate subspecies (A. f. funereus L.), common in the Voronezh region and in the north of the Rostov region. The bird finds the most optimal conditions in old dark coniferous and mixed forests of the Western Caucasus, and its maximum abundance is noted in the Teberda Nature Reserve (1 pair per 10 sq. km). In the Central and Eastern Caucasus, it lives in old deciduous forests (low-height mountains) and in pine forests (middle-height mountains). The population of Tengmalm’s Owl in the North Caucasus is considered relatively stable, and its total number is now estimated at 1-2 thousand pairs, including 200 - 400 pairs living in Karachaevo-Cherkessia and 20 - 30 pairs living in Adygea. Ecologically, Tengmalm’s Owl is closely connected with the Black Woodpecker (Dryocopus martius), whose old hollows it usually nests in. The birds display from January to May, but most actively in mid-April. In late April, they lay eggs, and fledg-lings appear in June - July.

The results of our bird counts carried out in 1996-2017 in the Inner-mountain and High-mountain Dagestan are analyzed. The bird specific composition, average popula-tion abundance and ecological structure of the avifauna in two difficult-to-reach mountain areas of the republic are described for the first time. With the help of cluster analysis it is established that the avifauna patterns of most of the key areas are not only similar but also unique because of the high heterogeneity of these biotopes and, correspondingly, the faunal differences formed in the mountains under insufficient (Inner-mountain Province) and sufficient (High-mountain Province) moisture. Specific features of the avifauna in the studied areas are assumed to be attached not only by residential communities of typical mountain birds, but also by adapted populations of migratory birds of plains nesting in the mountains. Analysis of our collected material gives a clear view of the specific diversity and territorial distribution of the birds as well as of the avifauna resources of the Inner-mountain and High-mountain Dagestan.

A comparative analysis of biological properties of several subtypes of mountain and plain chernosems in the Central Caucasus (within Kabardino-Balkaria) was conducted. Statistically significant differences between the parameters of biological activity in the upper horizons (0 - 20 cm) of the soils under study were revealed. Mountain chernosems are characterized by the high humus content (by 38% on average), an increased activity of dehydrogenase (by 42%) and urease (by 35%), and all microbial parameters (by 12 - 53%). The invertase activity was higher in plain chernosems (by 47% on average). Dispersion analysis has shown that the influence of formation conditions (mountain or plain) is a more significant factor for a number of the studied parameters than features of the studied soils at the subtype level. The strength of the factor of genetic differences lies in the range of 1 - 5%, while the influence of formation conditions ranges from 15 to 33%. The total biological activity of the upper horizons in mountain and plain chernosems was evaluated by means of an integral index of ecologico-biological soil status (IIEBSS) which shows a higher biological activity of the upper horizons in mountain soils (IIEBSS differences are within 5 - 18%).

The territorial structure and social organization of artificial groups of two subspecies of the midday gerbil (Meriones meridianus nogaiorum, M. m. psammophilus) were studied under semi-natural conditions. No significant differences in the space usage system of the subspecies under comparison were found. The structure of social interactions was found to be identical in females but different in males: M. m. nogaiorum males exhibited dominance hierarchy, whilst a despotic dominance was found in M. m. psammophilus males. M. m. psammophilus females also exhibited dominance hierarchy. Besides, avoiding same-sex conspecifics seems to be a typical behavioral strategy of M. m. psammophilus. These findings support our suggestion that M. m. psammophilus should be treated as a distinct species.

The paper presents the results of our four-year observation of Bulbocodium versicolor (Ker-Gawl.) Spreng populations in the Saratov and Volgograd regions. A low ecological plasticity of the species was established. Although the species grows in steppe phytocenoses that vary in composition and structure, the specimens’ morphology was rather conservative, which can be explained by the homogeneity of the species’ vegetation conditions over the territory under study during active vegetation and flowering. It is shown that in the Lower Volga region, B. versicolor is characterized by the reduced stress component of its life strategy and a low index of size plasticity. The species uses a ‘patient’ strategy. Morphologically, plants respond to stress by a diminishment of the reproductive organs and the reproductive-to-vegetative transition. The ecotopic and phytocenotic tolerance of B. versicolor manifests itself in the species’ capacity to retain the occupied territory for a long time and to avoid competition via habitat selection. According to the conservation priority index, the majority of B. versicolor populations in the Lower Volga region are at high risk of becoming endangered and their preservation requires immediate action. The decline in the species’ size in the region is most likely induced by the climate aridization and direct human impact, specifically the transformation of wild lands to croplands. There is no decisive proof that overgrazing and gathering for bouquets have had any significant negative impact on the species. It may be attributed to the secluded location of the remaining species’ habitats that makes the species practically inaccessible in the period of massive flowering.

The total abundance of bacteria, the numbers of saprophytic, oligotrophic and sulfate -reducing microorganisms, the shapes of bacterial cells, the primary and bacterial production, organic matter destruction, and the rate of sulfate reduction were studied in small Karelian lakes during the stagnation period. It is shown that the uneven vertical distribution of light, temperature, oxygen and hydrogen sulfide creates ecological niches for the development of many various groups of microorganisms. In most lakes, the minimum abundance of microorganisms was found in their surface water layer while its maximum was in the near-bottom ones. The trophic status of a waterbody has a great influence on the formation of microbial communities and their functioning. Autochtonic organic matter in closed forest lakes studied (the local term “lamba”) was formed due to phytoplankton photosynthesis but the bacterial production exceeded the primary one in the hypolimnion of eutrophic lakes. The content of hydrogen sulfide, the abundance of sulfate-reducing bacteria, and the rate of sulfate reduction were maximal in the bottom sediments of eutrophic lambas.

The foraging behavior of the Blackbird and Fieldfare in the city of Kaliningrad was studied. A similarity of the feeding habitats used by thrushes is noted. The main type of fodder stations during the reproductive period are lawns with low vegetable cover, rare-fied as a result of human influence, while these are squares and gardens with fruit bushes and trees during the autumn and winter period. The use of fodder stations and fodder objects of anthropogenic origin is noted for the blackbird out of its period of re-production. The differences in nutrition behavior consist in the frequency and sequence of the use of foraging acts and are associated with thrushes’ use of various quantities of objects from the soil and from its surface. During the breeding season, sweeping motions of the beak are the most characteristic for the Blackbird, and digging up objects from the soil are for the Fieldfare. The differences in the foraging behavior of thrushes in Kaliningrad (in contrast to natural habitats) are expressed as an increased variety of the foraging methods used and a significantly prolonged duration of examination for the Blackbird and Fieldfare, respectively. These differences are due to the manifestation of specific features in specific places of feeding.

The paper presents the results of our research on the foraging activity of ants in forest-steppe biotopes of the Saratov region. The food spectrum of ants was found to include small invertebrates (mainly insects), plant seeds and aphid honeydew. Ants are able to switch to the most massive type of food. F. pratensis behaves as a species with a daytime or morning-evening activity type, depending on the weather conditions. F. rufa is a species with a daily activity type.