Nesting features and the ecology of the eagle owl (Bubo bubo L.) in the northwestern part of the Trans-Volga clay semi-desert were studied in 1980–2024. Here, during the breeding season, the eagle owl is associated with local habitats of lake depressions and river valleys, and its nests are confined to steep slopes. Our main material was collected in a deep depression of the lake Elton (mainly on the territory of the Elton Nature Park), where 232 nesting cases were recorded in 1980–2024. 9 resident breeding sites have been identified there, where eagle owls have been nesting for many years in succession. With the development of farm cattle breeding, additional ones began to arise in the vicinity of some resident sites, forming a united nesting group with the resident. They were inhabited by couples disturbed in the residential areas, and, after their departure, young birds. All the nesting groups represented by resident and additional nesting sites were no longer functioning by the 2010s. When there were 5 to 9 breeding sites in the Elton region in 1980–2017 and 3 to 9 pairs nested annually, then only 2 breeding sites were noted in 2018–2023, almost all the nests of these pairs having been destroyed by cattle. The eagle owl population group, confined to the Elton Lake depression, is the core of the Elton–Khara population, since the conditions for eagle owl nesting are poor in the middle and upper reaches of the Khara River and the gullies flowing therein. For 45 years, an average of 5.2 pairs per year nested there and more than 19 birds (about 14 mature individuals) were present in the population annually. It is obvious that it is the Elton–Khara population that constantly “feeds” the eagle owl groups around the lakes Botkul, Bulukhta and Sorkul, which largely ensures the preservation of the species throughout the northwestern Trans-Volga region.

The influence of slope exposure on the population structure, morphometric features and reproductive characteristics of the rare orchid Cypripedium calceolus L. on karst landscapes of the Southern Timan in the territory of the Paraskiny Lakes Nature Reserve (northeast of the European Russia) was studied. In 2023, six populations of the species were surveyed on karst landforms, namely: five ones on slopes with different exposures, and one on a flat area. It has been revealed that the species forms its largest populations on the slopes of the western and northwestern exposures. Generative shoots damaged by light frosts were noted in all populations, and their share was more than 50% on the western slopes. The slope exposure affects the morphometric parameters of shoots and seeds. Fruit set is associated with both weather conditions and exposure, namely: the lowest fruit set was noted on the cold northwestern slopes, while the highest was on the southern ones. A decrease in the actual seed productivity of the fruit was revealed as the orientation of the slopes changed from north to south (from 9861 down to 3761 pcs), which is associated with the underdevelopment of some seeds. The average actual seed productivity of the generative shoot at the karst outlets of the Southern Timan was 1292 pcs (from 985 up to 1769 seeds in different populations). Along with the vegetative renewal characteristic of this species, seed renewal was also noted in the studied populations, as evidenced by the presence of juvenile individuals therein, whose proportion varied from 1 to 13.5%.

A comparative analysis of the composition and structure of plant communities in two places of the former habitat of Spermophilus suslicus in the Nikolaevsky district of the Ulyanovsk region is provided. Our analysis of the current state of S. suslicus populations in the Volga region has shown that over the past fifty years there has been a critical decline in the numbers of the species, and even its complete disappearance has been noted in some regions. A number of researchers note that dynamic changes in vegetation have certain influence on these processes. Therefore, the goal of our work was a comparative study of the vegetation of biotopes at the time of high numbers of animals against the background of intensive grazing and in the absence of gopher settlements for more than 15–20 years in the absence of grazing. Our studies have shown an increase in the species richness and structural diversity of communities due to the introduction of species from the upland, nemoral and boreal ecological-coenotic groups into their composition. Phytocenoses of steppe meadows with a high participation of Festuca valesiaca, Poa pratensis, Helictotrichon pubescens, and Elytrigia repens after the cessation of grazing are replaced by cenoses of meadow steppes with the dominance of Bromopsis riparia, Poa angustifolia, and Calamagrostis epigeios. There is an increase in the total projective cover of the grass stand (from 40 up to 60– 70%). Forage species that are background ones when the number of animals is high sharply reduce their participation in the grass stand. Changes in the ecological conditions of biotopes are characteristic, namely: modern communities are formed in drier, less nitrogen-rich and “acidic” habitats. The preservation and possible restoration of spotted ground squirrel settlements in the Volga region is possible subject to scientifically based anthropogenic impact, implemented in the form of haymaking and grazing.

The paper presents the results of our study of a small ground squirrel (Spermophilus pygmaeus Pallas, 1779) population in the territory of the Volga–Ural interfluve between 1940 and 2023. The influence of global warming on the population dynamics of this species in the Volga– Ural steppe natural plague focus is considered. Data from the annual censuses of the small ground squirrel abundance (number of individuals per 1 ha); reproduction intensity indicators; average monthly air temperature indicators at weather stations in the town of Kharabali for the period of 1940–2023 were statistically processed and analyzed. It is emphasized that the population dynamics of this species is determined by a whole complex of natural and anthropogenic factors. At the same time, in semi-desert conditions, the limiting factor for the small ground squirrel population is the distribution of air temperature and precipitation over seasons and years. The influence of temperature in January–February, which provoke emergence to the surface when small ground squirrels awaken from hibernation, is assessed. The main mechanism determining the negative impact of modern climate warming on the small ground squirrel population in the Northern Caspian Sea region has been established.

The contamination of gray forest soils with oil and diesel fuel at concentrations of 50, 150 and 300 ml/kg is shown to lead to a decrease in their capillary moisture capacity. When applying 50, 150 and 300 ml/kg of oil, this indicator decreased from 62 (corresponds to the best capillary moisture capacity) down to 22.6, 19.1 and 12.6%, respectively. The effect of diesel fuel on the capillary moisture capacity of the soil was similar. In the presence of 50, 150 and 300 ml/kg of this oil product, the capillary moisture capacity of the soil decreased from 62% down to 28.3, 20.0 and 13.8%, respectively. As a result of the introduction of the microbial oil-destroying preparation “DOP-UNI” and subsequent exposure for 3 weeks, it was possible to partially restore this agrophysical characteristic of the soil. Even during such a short exposure time, the capillary moisture capacity of the oil-contaminated soil (50–300 ml/kg), after treatment with the biological preparation, increased by 1.3–1.8 times compared to an untreated oil-contaminated sample. However, its values still remained lower than in uncontaminated soil samples. A similar trend was noted in our experiment with diesel fuel. In addition, the treatment of oil-contaminated soil with the biological preparation “DOP-UNI” for 3 weeks led to a decrease (by ~20%) in phytotoxicity at the level of oil contamination up to 150 g/kg. The obtained data allow us to judge the prospects of using the biopreparation “DOP-UNI” for soil remediation in the case of contamination with petroleum products and restoration of their agrophysical properties. At the same time, lowering the temperature down to 10°C did not significantly affect the effectiveness of the biopreparation, at least in the described 3-week experiments. This indicates the possibility of its use in low-temperature conditions, which is typical for the main oil production sites in the Russian Federation.

Modern animal husbandry requires new environmentally friendly technologies for the processing and disposal of its by-products (BPAH), namely: manure and manure effluents from livestock complexes. One of these technologies is the production of reconstituted litter (RL) in Bedding Recovery Units (BRU) from cattle manure, introduced at one of the dairy complexes in the Kirov region. The recycling technology used made it possible to obtain a homogeneous product of a soft, loose consistency, high hydroscopicity, brown color with a weak characteristic earthy odor. Manure processing in BRU for 24 h at a temperature within 69±4°C contributes to a significant decrease in the humidity of manure effluents, an increase in the mass fraction of organic matter, ash content, pH, as well as a significant decrease of the total number of microorganisms (MO) (by 68.2 times) and species diversity (by 2.2 times). Proteus, Fusobacterium, Prevotella, Pseudomonas, Peptococcus, Aspergillus, and Klebsiella, which are among the causative agents of mastitis, have disappeared from the microbiota. The numbers of opportunistic Enterococci decreased from (8.0±0.5)×10⁶ down to (5.0±0.5)×10⁴ CFU/ml. After processing in BRU, Bifidobacteria took a dominant position in the composition of microbiota in RL (63% of the total number of identified MO). This fact should be regarded as an advantage of the used technology and one of the advantages of the RL. However, conditionally pathogenic microorganisms of the genera Clostridium, Bacteroides, Peptostreptococcus, Veillonella, and Candida showed high resistance to manure effluent processing in BRU. According to the chemical analysis results, the content of cattle on RL led to the accumulation of nitrogen, phosphorus and potassium in litter manure, which is due to the gradual degradation of organic components of RL during recycling. The presented results can be used to optimize the parameters of processing cattle manure using BRU to improve the quality of RL.

The protected area of the Moulouya River mouth, also known as a SIBE (Site of Biological and Ecological Interest), is one of the most important and vulnerable freshwater reserves in the southern Mediterranean. This site is characterized by a wide variety of habitats that support rich aquatic biodiversity with a high degree of endemism. It was also one of the first wetlands in Morocco to be invaded by the marine and invasive American blue crab, Callinectes sapidus Rathbun, 1896, following its initial establishment in the Marchica Lagoon. Since its first detection in 2019, the blue crab has been expanding its range upstream in the Moulouya River, now reaching areas home to some of the last populations of endemic and patrimonial species in Eastern Morocco. In this paper, we compare the abundance of certain patrimonial species in the Moulouya SIBE before and after the arrival of the blue crab, focusing on the Moroccan endemic freshwater mussel Unio foucauldianus Pallary, 1936, and the freshwater crab Potamon algeriense Bott, 1967. We observed a complete disappearance of these species in certain areas of the lower Moulouya, which could likely be attributed to predation by the blue crab. The predation and migration behaviour of the blue crab in the Moulouya River aligns with what has been described in the literature for its non-native range.

The paper briefly relates the history of the white stork’s expansion into Karelia (Northwestern Russia, 61° N, 33° E), this species being red-listed with a 3NT status (rare, near threatened) in the regional Red Data Book. The western populations of the species declined dramatically in the second half of the 20^th century, but targeted conservation actions have helped the species numbers to be restored. However, its West European populations are still listed in column A (category 3b) in the Action Plan of the African-Eurasian Waterbird Agreement (AEWA). In view of the remaining risks and the tangible changes having occurred in the population size, it appears important to monitor the species’ distribution range and possible pathways of its expansion to new regions. The white stork’s breeding range currently encompasses Europe, excluding its northern regions, and reaches into the westernmost parts of Russia up to the southern districts of the Leningrad Region in the north. Vagrant birds are occasionally seen in central and northern districts of the Leningrad Region and even beyond, in Karelia. In this study, we have processed and synthesized archival, including partially published, and new records of solo individuals and groups of birds of this species from areas north of the regular breeding range and described some attempts of white storks to breed in these northern regions. We demonstrate that since the late 1960s, these birds have been regularly showing up in southern parts of Karelia, sometimes even farther north, and making occasional breeding attempts, pushing their permanent breeding range to the north and north-east. Having analyzed the records, we conclude that the visits of white storks to northern regions have become regular in the previous decades, but their attempts to breed there are still episodic and largely unsuccessful, suggesting that this species has not yet colonized Karelia as a breeding region.

The article present the research results of the secret toad-headed agama (Phrynocephalus mystaceus mystaceus Pallas, 1776) population structure on the Sarykum sandy massif (N 43°00'23.9", E 47°14'04.3"). The purpose of the study was to clarify features of the lizard population structure in the conditions of an island habitat: an isolated sandy area. The species' settlement in Sarykum featured a very high population density, averaging 82.1 ind./ha, a relatively small average size of individual home ranges and their significant overlap within sexual groups, namely: on average 69.7±33.32% for males, 50.7±35.92% for females and 57.5±39.41% between the home ranges of females with males, respectively. The overlap of home ranges within the group of young animals was significantly greater, 93.2±12.9%. Another peculiarity of the settlement was the predominance of immature individuals in the sedentary part (1.7:1), whose 1-2-day sites moved around the territory of the settlement. The latter is probably connected with the desire of the young to gain a foothold in any part of the overpopulated territory. A flow of migrants equal to 25.7 ind./ha per week passed through the settlement territory, consisting in equal parts of sexually mature and immature animals. An incomplete overlap of the territories of females with those of males could be considered as a possible element of the abundance autoregulation mechanisms, which reduces the number of meetings of sexual partners. All specific features of the settlement are apparently connected with the island position of the population.