In our previous study (Belenkova et al., 2025), we investigated the accumulation of heavy metals in the organs and tissues of striped field mice in the spring. The obtained data on the seasonal patterns of bioaccumulation were contradictory. We repeated our study using samples of striped field mice captured in the fall and compared the obtained data with the spring ones. It was shown that, overall, heavy metal (especially Pb) concentrations in the spring exceeded their fall levels. However, the patterns of heavy metal accumulation in the tissues of animals in specific parks remained the same, namely: the Filevsky Park remained the most polluted, while the Ostankinsky park remained the cleanest. These results could potentially be used to develop test systems for comprehensive assessments of the ecological state of urban ecosystems, taking into account the seasonal and spatial dynamics of heavy metal circulation in the environment and in free-living species.

: In the past, the Palm Dove (Streptopelia senegalensis) was only distributed in Africa, Western Asia and Hindustan, from where it relatively recently penetrated into Central Asia. In the second half of the 20th century, the Palm Dove began to populate Transcaucasia and also appeared for breeding in the North Caucasus, but this part of its range is still not reflected in the overview maps of this species distribution. The Palm Dove biology has been studied in detail in Central Asia, but in Russia, until recently, information about its ecology was almost absent. In Dagestan, on the lowlands along the Caspian Sea coast, a relatively stable range of the Palm Dove was formed in the 21st century. It is now common in cities, nesting mainly on buildings, but it practically does not penetrate north of Makhachkala City. In the Ciscaucasia, only small isolated foci are known, where episodic nesting of individual pairs is assumed, and occasionally vagrant specimens are encountered, penetrating as far north as Elista and Astrakhan cities. However, due to current global warming, this sedentary species may soon continue to spread across the southern Russia, primarily developing urbanized territories. Therefore, here, in the cities, it is necessary to continue monitoring of the southern Russian populations of the Palm Dove, focusing on studies of the ecological relationships of this species with competitors and predators, as well as on clarifying the role of abiotic factors in the dynamics of its numbers.

The article presents the characteristics of the biodiversity of opisthorchids and the infestation of additional hosts in various aquatic ecosystems in a metropolitan area (Novosibirsk city). The objectives of the study included determining the species composition of opisthorchids metacercariae, analyzing their occurrence and abundance in fish in each of the three groups water bodies, namely: the Ob River, its tributaries and Berdsk Bay, located within the boundaries of Novosibirsk city and differing in a set of abiotic and biotic characteristics. The composition of the metacercariae hemipopulation in the surveyed water bodies was identical, being represented by three species, namely, O. felineus (Rivolta, 1884), M. bilis (Braun, 1890), and M. xanthosomus (Creplin, 1846). However, the infestation of an additional host by opisthorchids larvae of individual species in different water localities was variable and was determined by local environmental features. The most common opisthorchids species in fish caught in the Ob River and Berdsk Bay is O. felineus, the subdominant ones are M. bilis and M. xanthosomus, respectively. In the Berdsk Bay small local fish (ide, gudgeon, and dace) were most frequently and intensively infected with O. felineus and M. bilis, while in the Ob River, O. felineus and M. xanthosomus metacercariae were more often recorded in ide. In the additional host inhabiting the Ob tributaries, unlike other water bodies, M. bilis and O. felineus were dominant, with M. bilis metacercariae more often detected in small local fish: gudgeon and ide, and O. felineus in roach (EI = 34.3%). Our analysis of the diversity of opisthorchid metacercariae representatives using biological indices indicates a simplified structure of opisthorchid communities in each water body. The most complex structure of the opisthorchid hemipopulation was found in the Ob tributaries (H = 1.01), then in the Berdsk Bay (H = 0.51) and in the Ob River (H = 0.32). The highest values of dominance indices (D) are characteristic of the main channel of the Ob and the Berdsk Bay, which indicates the abundance of one species of opisthorchid, namely, O. felineus. Low values of the Simpson index in the Ob tributaries indicate the uniformity of the abundance of metacercariae and the absence of obvious dominance of any species. 

The article presents the results of our observations of the behavior of farm sables on a fur farm located 100 km south of Yakutsk city. The behavior was analyzed on video recordings obtained with the help of outdoor video cameras, around the clock throughout the year. The observations showed a significant correlation between the time of use of the insulated shelter and the maximum (r = 0.68; α ≤ 0.01) and minimum (r = 0.66; α ≤ 0.01) air temperatures. The longest stay outside the house was observed in the spring and summer periods. With the transition of daytime temperatures above the zero mark in April, the sables practically ceased to be used by insulated houses. During the hottest days of the summer period, the use of cabins increased again. There was almost no activity during the whole day. The longest stay of sables in insulated shelters was in December (on average 16–17 hours) and January–February (on average about 18 hours). In January–February, their activity prevailed in the evening (19.9 and 27.9%, respectively). From March to August, the greatest activity was confined to the night period (29.8–44.9% of the total time of the period). In September– December, the sables’ activation was observed in the morning period, from 6 to 12 AM (43.3– 58.4%). At night, the sables were active on average 27.6±4.0% of the total time of the period. In the morning, this indicator was 28.3±5.4%. The lowest activity was recorded in the afternoon – 19.4±4.8%. In the evening, the activity of the animals increased up to 24.6±2.8%. The annual dynamics of the body temperature of the studied farm sable correlates with the ambient temperature (r = 0.41; α ≤ 0.050). The lowest average daily body temperatures were recorded in January (+36.8±0.03°C; n =744; limit from +33.9°C to +38.53°C), the highest – in July (+37.2±0.02°C; n = 744; limit from +34.9°C to +38.8°C). A comparison of the indicators providing cold tolerance in caged animals and sables from natural populations showed almost identical results.

The aim of this review is to summarize current knowledge on the factors influencing the toxigenicity of cyanobacteria of the genus Microcystis and their ability to synthesize hepatotoxic peptides known as microcystins. Environmental factors affecting the ratio of toxigenic to nontoxigenic strains in aquatic ecosystems, as well as the expression levels of genes responsible for microcystin biosynthesis, are analyzed. Particular attention is given to the roles of temperature, light intensity, eutrophication, oxidative stress, and the availability of trace elements. Methods for monitoring toxigenic populations, including molecular biological approaches such as PCR and RT-PCR, are also discussed. Understanding the environmental drivers of toxigenic Microcystis proliferation may contribute to predicting the occurrence of microcystins in drinking water sources and determining optimal sampling periods for toxin monitoring in source waters.

The demographic structure of the Volga–Ural population of saigas migrating to the Saratov Trans-Volga region is shown. It has been established that animals from the West Kazakhstan region (Republic of Kazakhstan) appear in the border areas of the Saratov Trans-Volga region in the second and third decades of April, depending on the weather conditions of specific years. At the end of May, migration mainly ends, and the animals split into groups and spread across a number of areas in the Saratov Trans-Volga region. According to our observations and survey data, between 2011 and the early 2020s, the number of saigas entering the Saratov Trans-Volga region in spring ranged from several thousand to tens of thousands. In recent years, as the entire population has grown, this figure has increased to several hundred, and in 2025, to many hundreds of thousands of individuals. According to our observations, both females with calves born in Kazakhstan and pregnant and barren females migrate to the region. The number of males migrating together with herds of females is small. At the beginning of migration in 2025, the number of arrivals per adult female was 0.9 individuals, but this reproductive rate increased to 1.6 individuals in the third decade of June. This circumstance indicates the calving of female saigas in the Saratov TransVolga region, which is confirmed by our survey data. In the last decade of July, when the entire territory of saiga distribution in the Saratov Trans-Volga region was surveyed, this indicator was 1.5 individuals. Most likely, this fact could be explained by some departure of yearlings. The number of adult males increases from 2.3% in the first ten days of May to 6.7% in the third ten days of June and to 8.3% in the third ten days of July. From these data, we can conclude that the migration of males is spread out over time, but most of them remain in Kazakhstan, which is confirmed by our observations during expedition trips to the West Kazakhstan region in 2011–2019 along the Zhanybek–Aralsor and then Zhanybek–Borsy routes.

The paper presents a study of blueberry-sphagnum spruce forests (from Picea abies (L.) Karst.) in the Central Forest Reserve (Tver region, southern taiga). The sample plots covered 7 km2of forest. Coals were found under the roots of fallen trees in all the test areas. Reconstruction of the history of disturbances based on spruce cores showed that the surveyed area was subjected to high-intensity fires in the 1770s–1780s and 1840s–1870s. In addition, part of the spruce forest experienced major wind disturbances in the 1900s (reconstruction), as well as in 1987, 1996 and 2017/2018, as well as the mass drying of spruce in the 2010s and 2020s. Over the past 250 years, there has been a decrease in the frequency of pyrogenic disturbances and an increase in wind damage. The rarity of fires since the second half of the 20th century is an obvious result of the strict protection of the reserve. The period from the last detected major disturbance to the partial or complete death of the stand (currently) averaged 150 years. Judging by the taxation descriptions of 1939, in the stands of 17 out of 20 sample plots (85%), spruce dominated 70 years after a major disturbance (mainly after a fire), and later, over the next 80 years, the ratio of spruce and small-leaved tree species in the stand changed from 8:2 to 9:1. In the moss cover during this period, there was a change of dominants, namely, Polytrichum commune Hedw. to Sphagnum girgensohnii Russ. Over the 250-year history of the surveyed spruce massif, the structure of the stand of different ages has not been achieved. 150 years after the last major violations, two main generations of spruce are distinguished in the age structure. That is, on the southern border of the taiga zone, speaking about the stability of primary stands, we can only talk about the stable (continuous) existence of a spruce forest in this territory, which is determined by the possibility of its selfrenewal. Currently, in the Central Forest Reserve there are large areas of spruce young trees at the place of hurricane falls and areas of complete drying of the spruce stand. Such forests are the most fire-prone. Therefore, at the present stage of the dynamics of the spruce forests in the Central Forest Reserve, it is extremely important to protect the forest from fires.

A revision of the species richness of four vertebrate classes (mammals, birds, reptiles, and amphibians) within the territory of Russia was conducted. The regional-level biome was adopted as the territorial unit. An increase in species richness towards the south is characteristic for all classes, with specific differences for each class reflected on our plotted maps. The zones of high diversity partially overlap; however, the biomes with the maximum values do not coincide. For mammals, these are the Black Sea-Ciscaucasian (113 species) and the Zavolzhsky-Kulunda (114 species) steppe biomes. For birds, they are the Sayan-Southern Transbaikal (262 species) and the Altai-Sayan (275 species) orobiomes. For reptiles, it is the Dagestan orobiome (31 species) and the Caspian desert-steppe biome (37 species). For amphibians, it is the Dnieper-Volga biome, which includes the Kaliningrad region (13 species).