A Central Asian leopard named Chilmas, released in July 2023 in North Ossetia, made its first foray into neighboring Kabardino-Balkaria at the beginning of winter. He passed through the highlands of the Alania National Park, at an altitude of about 3,700 m above sea level, not far from the site of the first release of leopards in Ossetia in the summer of 2018. This is the southernmost crossing of released leopards from Ossetia to Kabardino-Balkaria. All our other cats who visited the Kabardino-Balkarian Republic earlier (namely, Leo, Laura and Volna) made similar transitions much further north, where human presence was more pronounced and probable, but the territory itself was less risky in terms of topography. While Chilmas was mastering the highlands, he did not show up on our radars for two weeks, which caused us noticeable concern, especially against the backdrop of recent reports regarding Leo. We are very glad that he safely overcame the winter slopes and, hopefully, enjoyed the magnificent views of the snow-capped Caucasian peaks. Chilmas hunted twice during December, but clusters of his locations in the intended hunting areas are currently inaccessible to our field researchers. We hope that during the period when the situation becomes less dangerous for avalanches, there will be an opportunity to examine them and find out who Chilmas was hunting in the highlands. The latest data on his hunts contain information about his prey of ungulates. Since November to date, Chilmas has covered an area of about 1,672 km2 during the survey of new habitats, thereby having developed a total area of about 1,726 km2. It should be noted that from the moment of release, Chilmas was very careful and did not make long treks, preferring the forest area of the Ardon-Urukh interfluve, and only in the second part of November began to actively move to the West-South-West. Over the entire period of his free and independent life, Chilmas traveled a distance of 697 km, of which 143.5 km in December. The maximum distance it has moved from its “starting point” (place of release) is now about 37 km. Since the release of Chilmas, we have registered 15 clusters of locations - places where he hunted. If you visualize Chilmas's track, you can see that it runs tangentially along the tracks previously marked for Laura and Leo. Thus, he followed the tracks of his relatives, which they had left in Kabardino-Balkaria earlier. The team studying the processes of restoration of the Central Asian leopard in the Caucasus sincerely congratulates everyone on the upcoming New Year and Christmas! The program for the restoration of the Central Asian leopard in the Caucasus is being implemented by the Russian Ministry of Natural Resources with the participation of the Sochi National Park, the Caucasus Nature Reserve, the Federal State Budgetary Institution "Reserve Ossetia-Alania", the Moscow Zoo with the assistance of the International Union for Conservation of Nature (IUCN). Scientific support of the Program is provided by the A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences (IEE RAS) in collaboration with the A.K. Tembotov Institute of Ecology of Mountain Territories RAS (IEGT RAS), the Caspian Institute of Biological Resources of the Dagestan Federal Research Center of the Russian Academy of Sciences (PIBR DFRC RAS) and zoologists of protected areas. In North Ossetia, financial support for scientific support of the population restoration program is provided by the RusHydro company.

Fig. 1. Tadpoles of the genus Kalophrynus, top and side view: (A, B) K. interlineatus; (C, D) K. honbaensis; (D, F) K. cryptophonus. Scale bar 5 mm. In 2023, the journal Vertebrate Zoology published an article by Anna Vasilyeva, an employee of the Institute of Ecology and Evolution of the Russian Academy of Sciences (co-authored with Nguyen Thi Van), devoted to the evolution of the larvae of tropical frogs that switched to reproduction in arboreal microreservoirs - phytotelmata. The use of phytotelmata for breeding is widespread among amphibians living in complex tropical ecosystems. On one hand, this strategy allows developing tadpoles to avoid dense interspecific competition and predation pressure. On the other hand, in closed microreservoirs, tadpoles face a lack of food resources. One way to overcome these limitations is oophagy, that is, “egg cannibalism” - feeding on eggs of the same species of frogs to which the tadpoles themselves belong. Larval oophagy is common in many families of frogs whose tadpoles are generally prone to predation (e.g. Hylidae, Leptodactylidae, Rhacophoridae, etc.). However, it is much more surprising for the family of narrowmouths (Microhylidae), whose very specialized tadpoles are adapted to filter small organisms or organic particles from water. The transition from microfiltration to macrophagy and its special case, oophagy, is a complex evolutionary task that requires significant morphological changes in the oral apparatus, gill apparatus (which acts as a filtering structure) and the digestive system. An excellent model for studying this evolutionary transition were the tadpoles of three closely related, very similar species of frogs of the genus Kalophrynus, one of which (K. interlineatus) lives in small still water puddles and is a microfilter, and the other two develop in phytotelms - large water-filled tree hollows (K. honbaensis) and hollow bamboo stems (K. cryptophonus) and are obligate oophages. The gradual transition from open reservoirs to voluminous cavities holding up to several liters of water in tree trunks and logs and to narrow gaps in bamboo internodes with a volume of only 20-50 ml in the series of tadpoles K. interlineatus - K. honbaensis - K. cryptophonus is accompanied by noticeable external changes : flattening of the body, elongation of the tail and reduction of the fins (Fig. 1), which facilitates locomotion in the phytotelm viscous from mucus. Fig. 2. The structure of the elements of the cartilaginous skeleton in tadpoles of the genus Kalophrynus with different trophic specializations. Top: skull, dorsal view; in the center: lower jaw, frontal view; below: hyobranchia, ventral view. (A–B) K. interlineatus; (D–F) K. honbaensis; (G–I) K. cryptophonus. Legend: arso infraorbital bridge, bsb posterior copula, bsh anterior copula, cad otic capsule, cbr ceratobranchial cartilages, cir inferior labial cartilage, cmk Meckel's cartilage, cpo ridge of the auricular capsule, cqd quadratocranial commissure, crh ceratohyal cartilage, csr superior labial cartilage, ctr horns trabeculae, fsoc infraorbital fenestra, part articular process, pas ascending process, pdq palatine quadrate cartilage, plhyp hypobranchial plate, plo larval auricular process, plp posterior lateral process, pranl anterolateral process, prant anterior process, prbrh branchial processes, prlat lateral process. Scale bar 1 mm. The transition from feeding on small organisms and organic particles suspended in water to the absorption of whole eggs - a relatively large, nutrient-rich food - leads to a progressive shortening of the digestive tract and the appearance of a voluminous stomach. In addition, the change in trophic adaptations is accompanied in the same series of tadpoles by an expressive transformation of the cartilaginous larval skeleton (Fig. 2): the skull loses the wide lateral processes (prlat), characteristic of microfilter tadpoles; the posterior part of the palatoquadrate cartilage (pdq) is successively reduced; the weak, thread-like lower labial cartilage (cir) becomes more powerful, adapted to capture larger food; the gill apparatus increasingly loses its filtering functions: the openwork gill basket (cbr I-IV) is gradually reduced, the hyobranchium as a whole becomes more robust, adapted for more powerful suction. The results obtained clearly show how the adaptive evolution of tadpoles occurs as they develop new ecological niches in tropical ecosystems, and how the larvae of closely related frog species acquire greater morphological diversity than adults. The study was carried out on the basis of the Joint Russian-Vietnamese Research and Technology Center. Publication imprint: Vassilieva A.B., Nguyen T.V. (2023) Restricting living space: Development and larval morphology in sticky frogs (Microhylidae: Kalophrynus) with different reproductive modes. Vertebrate Zoology 73: 367-382. https://doi.org/10.3897/vz.73.e98618

Bolshoi Shantar Island: Bolshoye Lake (top) and researchers at work (middle); Tugur Peninsula: Lake Ongachan Photos by R.R. Borisov After the cessation of research in the first half of the 20th century and the closure of whaling, the Shantar Islands, located in the north of the Khabarovsk Territory, fell out of the orbit of the practical interests of society. Lately, the archipelago has received a lot of attention from tourists eager to admire the rocky shores, fog and whales. This trend was broken by scientists from the A.N. Severtsov Institute of Ecology and Evolution RAS. Together with colleagues from the All-Russian Research Institute of Fisheries and Oceanography and Moscow State University they studied the fauna of invertebrate organisms in lakes, streams and rivers of the Shantar Islands. The work performed is the first attempt to study the hydrobionts of the archipelago, including the analysis of both zooplankton living in the water column and benthos inhabiting the bottom. More than 150 species of freshwater and brackish-water invertebrates were discovered for the first time in the reservoirs of the Shantar Islands. The fauna is represented mainly by species with wide ranges, with a small proportion of species confined to the Arctic zone of Eurasia, Eastern Siberia and the Far East. When comparing the fauna of the Shantar Islands with other regions of the Far East, a smooth increase in species richness was discovered from the northern to the southern regions. At the same time, the proportion of species with a wide distribution gradually decreases in the same direction. These trends persist for all major groups of aquatic invertebrates. On the Shantar Islands, at the edge of land and sea, there is a continuous competition between fresh and salt waters. Rains and fogs flowing from the slopes of the ridges are gradually trying to reclaim the bays from the sea, turning them into brackish lagoons. In turn, the Sea of Okhotsk hits the shore with waves, penetrating into river mouths. Lake Bolshoye, located on the island of Bolshoi Shantar, experiences constant fluctuations in salinity, associated both with daily tidal cycles and with river and rain runoff. Due to its considerable extent, the lake maintains a salinity gradient. In this regard, the abundance of zooplankton in it changes abruptly, reaching a maximum in the zone of mixing of river and brackish waters, located in the middle part of the lake. In the same part of the lake, there is a sharp change in macrozoobenthos communities, when insect larvae, which predominate in the desalinated part of the water area, are replaced by crustaceans - amphipods. The research is a significant contribution to the study of the fauna of protected areas of the Russian Far East. Such work is necessary for the development of monitoring programs, as well as the development of environmental education within the framework of tourist local history routes in the Khabarovsk Territory. The research was carried out with the support of the Association of Nature Reserves and National Parks of the Khabarovsk Territory "Zapovednoe Priamurye" and LLC "Far Eastern Expeditions". Novichkova A.A., Borisov R.R., Vorobjeva L.V, Palatov D.M., Chertoprud M.V., Chertoprud E.S. The Influence of Salinity Gradient and Island Isolation on Fauna Composition and Structure of Aquatic Invertebrate Communities of the Shantar Islands (Khabarovsk Krai) // Diversity. 2023. 15. 1198. https://doi.org/10.3390/d15121198

Fig. 1. Parental species of hybrids - Djungarian hamster (left) and Campbell hamster (right). Scientists from the Institute of Ecology and Evolution of the Russian Academy of Sciences and the Faculty of Biology of Moscow State University conducted a pioneering study on the inheritance of the structure of ultrasonic calls in interspecific hybrids. Until now, it was known that when closely related species with very different sound signals hybridize, in hybrid individuals the sounds produced by phonation - vibrations of the vocal cords - have a structure intermediate between the two parental forms. However, the question of the inheritance of ultrasonic calls, which are whistles based on air turbulence, remained a blank spot. A description of ultrasounds was carried out in the young of laboratory lines of the Campbell hamster from the eastern (Mongolian line) and western (Kosh-Agach line) parts of the range, the Djungarian hamster, as well as hybrids between male Djungarian hamsters and female Kosh-Agach Campbell hamsters (Fig. 1). A total of 4,000 sounds were analyzed from 80 pups aged 4-8 days in the “isolation test”. All groups studied produced two categories of ultrasonic signals: low frequency, centered around 41 kHz, and high frequency, centered around 60 kHz, but in different percentages. Low- and high-frequency components could be present in the calls, either individually or together, forming ultrasound with two frequencies. Interestingly, when comparing different lines of Campbell’s hamster, it was found that there were more ultrasonic calls with a high-frequency component in the pups of the Mongolian line, and calls with two components in the pups of the Kosh-Agach line. In terms of the composition of calls, the hybrids did not show expected intermediate values between the parent species, but demonstrated signals with their own characteristics - ultrasounds with a low-frequency component were less common in them than in Campbell's hamsters, ultrasounds with a high-frequency component were less common than in Djungarian hamsters. Ultrasounds with two components were represented more often in hybrids than in both parental species (Fig. 2). Fig. 2. Occurrence of ultrasonic screams with low-frequency, high-frequency and two components. P.campM - Campbell's hamsters of the Mongolian line; P.campK - Campbell's hamsters of the Kosh-Agach line; P.sung - Djungarian hamsters; Hybrids - hybrids from a male Djungarian hamster and a female Campbell hamster of the Kosh-Agach line. Parameters such as duration and peak frequency were used to describe sounds and make intergroup comparisons. According to these characteristics, the calls of hybrids differed sharply from those of the young of the parent species - in hybrids, low-frequency calls were shorter and characterized by a lower frequency than in both parent forms, while high-frequency calls were longer, and the peak frequency was lower than in one of the parent species - Djungarian hamster (Fig. 3,4). It should be noted that the low-frequency signals of the pups of the two lines of Campbell's hamster differed significantly in both duration and peak frequency (Fig. 3). Fig. 3. Comparison of the parameters of low-frequency (LF USVs) and high-frequency (HF USVs) ultrasonic calls in baby hamsters of four experimental groups. The center point is the mean, the whiskers are SE. P.campM - Campbell's hamsters of the Mongolian line; P.campK - Campbell's hamsters of the Kosh-Agach line; P.sung - Djungarian hamsters; Hybrids - hybrids from a male Djungarian hamster and a female Campbell hamster of the Kosh-Agach line. Different letters indicate significant differences between values (p>0.05, Tukey post hoc). It was shown for the first time that for the whistling calls of mammals, the fundamental frequency of calls of interspecific hybrids can have values that lie far beyond the frequency range of the parent species. In the context of the known genetic determination of vocalization in rodents, this is an interesting result that raises many new questions for further research into the mechanisms of inheritance of the ability to vocalize. Fig. 4. Spectrograms illustrating low-frequency (LF USVs) and high-frequency (HF USVs) calls of pups from different experimental groups. P.campM - Campbell's hamsters of the Mongolian line; P.campK - Campbell's hamsters of the Kosh-Agach line; P.sung - Djungarian hamsters; Hybrids - hybrids from a male Djungarian hamster and a female Campbell hamster of the Kosh-Agach line. The study was published in the Elsevier journal Behavioral Processes. Semen V. Piastolov, Ilya A. Volodin, Nina Yu. Vasilieva, Anastasia M. Khrushchova, Olga N. Shekarova, Elena V. Volodina. Comparison of ultrasonic isolation calls of pure-breeding and interspecies hybrid Phodopus dwarf hamster pups // Behavioural Processes, 2023, v. 210, 104917 https://doi.org/10.1016/j.beproc.2023.104917

Otomis or African swamp rats are members of the mouse family and occupy the ecological niche of voles in Africa. This is expressed both in food preferences and in the appearance of the animals. The greatest species diversity of representatives of the genus Otomys is observed in the Eastern Afromontane Center of Biodiversity and Endemism, which includes the Ethiopian Highlands. The complex geomorphological structure of the highlands with many mountain ranges separated by the Rift Valley and deep river canyons limits the free movement of otomis, thereby creating the preconditions for active speciation processes. This is also facilitated by the pronounced diversity of habitats along the altitudinal gradient, where forest, heather and Afro-alpine belts are successively replaced. An international team of scientists, including the head of the laboratory of mammalian microevolution of the Institute of Ecology and Evolution of the Russian Academy of Sciences, Doctor of Biological Sciences. Lavrenchenko L.A. and a junior researcher in the same laboratory, A.A. Martynov, conducted a phylogenetic analysis and taxonomic revision of Ethiopian Otomys. The study is based on the combined use of genomic (high-throughput sequencing using the ddRADseq method) and morphometric (skull shape analysis) methods. Figure 1. A – Phylogenetic tree of Ethiopian Otomys. Distribution map of representatives of the phylogenetic groups SIMIENSIS (B) and TYPUS (C). The study results confirmed the presence of six endemic Otomys species in Ethiopia and significantly expanded the ranges of some of them. These six species are divided into two phylogenetic groups, each of which independently colonized the Ethiopian Highlands in the past. In addition, both molecular and morphological data identified a previously unknown lineage of Otomys, which is presumably a new species. The work was carried out within the framework of the Russian Foundation for Basic Research project No. 19-54-26003. The research results were published in the highly rated Zoological Journal of the Linnean Society. Mizerovská, D., Martynov, A. A., Mikula, O., Bryjová, A., Meheretu, Y., Lavrenchenko, L. A., & Bryja, J. (2023). Genomic diversity, evolutionary history, and species limits of the endemic Ethiopian laminate-toothed rats (genus Otomys, Rodentia: Muridae). Zoological Journal of the Linnean Society, 199(4): 1059-1077.

Yulia Kurbatova, head of the V.N. Sukachev laboratory of biogeocenology of the A.N. Severtsov Institute of Ecology and Evolution RAS, made a report “How the climate-regulating functions of ecosystems in Russia are assessed” at the Expert Discussion Platform “Climate Dialogues”. We publish the abstract of the speech. Special attention must be paid to the organization of high-precision instrumental monitoring of climate-active substances on the territory of Russia, A.N. Severtsov Institute of Ecology and Evolution RAS, which has been involved in this topic for more than 25 years. The V.N. Sukachev Laboratory of Biogeocenology has many years of experience in researching greenhouse gas flows at various levels of spatial averaging and is a leading Russian team developing a network of observations of ecosystem flows of greenhouse gases in various terrestrial ecosystems of the Russian Federation. The main research base of the Laboratory is the ecosystems of the Tver region is located on the territory of the Central Forest State Natural Biosphere Reserve, one of the oldest reserves in Russia, which represents a reserve of indigenous spruce forests and raised bogs. The Laboratory team is developing a local network of automatic ecological-climatic stations on the territory of the reserve to conduct high-frequency, continuous, year-round observations of the absorption and emission of greenhouse gases and environmental factors in forest and swamp ecosystems. Analysis of experimental data makes it possible to evaluate ecosystems as sinks or sources of greenhouse gases for the atmosphere. According to studies, currently almost all terrestrial ecosystems in Russia are sinks of greenhouse gases. However, different ecosystems are differently sensitive to climate change. Our task is to assess, based on the analysis of long-term data, the sensitivity of our country’s ecosystems to ongoing climate changes. The main result of our work is long-term data series obtained since 1998, which allow us to study the variability of both the concentration of greenhouse gases and their fluxes between the atmosphere and the ecosystems being studied. While the federal program of carbon testing sites is just at the stage of obtaining the first results of experimental observations, a number of teams in our country have been obtaining similar data for more than 20 years. These data are a goldmine for decision-making within the framework of climate change projects. Researchers are now united by the most important innovative project of national importance to create a network for monitoring climate-active sources in our country. A network of environmental and climate stations will be able to become a source of high-quality data on the balance of greenhouse gases for both business and political structures. As a rule, all environmental observatories or biological stations are equipped with modern instrumental bases. Research uses remote sensing tools, including to assess changes in the dynamics of ecosystem structure. Of course, such studies provide the opportunity to work with large data sets for scientific generalizations. Working at our observation sites allows us to participate in project activities; we implement grants from various scientific foundations, including interaction with international scientific teams. Long-term observation of the parameters of energy and mass exchange between terrestrial ecosystems and the atmosphere, in combination with observations of meteorological quantities, makes it possible to reduce the uncertainty in assessing the natural variability of the components of the greenhouse gas balance. We have the opportunity to examine the response of basic terrestrial ecosystem functions to modern climate change, including assessing the role of extreme weather events in the exchange of greenhouse gases. And of course, experimental data is material for clarifying the parameters of predictive models.

Deputy Director of the Center for Parasitology of the IEE RAS Mikhail Viktorovich Pridannikov took part in the Annual Meeting Indian Society of Plant Pathologysts & National Symposium program "Plant Pathology: Sustainable Approaches for Food Security and Human Health", held on December 8-9, 2023. The inviting party was the Institute of Agricultural Science Banaras Hindu University, Varanasi, Utar Pradesh, India - one of the oldest universities in India. During the visit M.V. Pridannikov gave a plenary report “Economically dangerous species of plant parasitic nematodes on agricultural crops in the Russian Federation today” on the topic of studying the diversity of parasitic nematodes on agricultural crops in Russia. The report aroused keen interest from Indian colleagues, including discussions of joint scientific research and student exchange within the framework of possible bilateral projects. During a discussion with the President of the Indian Society of Plant Pathology Dr. Chakrabarty of various problems with parasitic organisms on plants in both Russia and India questions were raised about the impact of climate change and increased mutual exchange of food products between the two countries on the spread of certain types of plant pathogenic organisms. An increase in the harmfulness of certain types of plant pathogens was noted, such as rust fungi on cereal crops, root-knot nematodes on vegetable crops, etc. The development of a biological method for controlling the number and harmfulness of parasitic nematodes on agricultural crops was discussed. During a trip to New Delhi, M.V. Pridannikov visited ICAR-Indian Agricultural Research Institute, New Delhi, India. M.V. Pridannikov got acquainted with the work of the Department of Nematology and held a meeting with the Director of the Department of Nematology, Dr. Pankaj. Issues of mutual cooperation were discussed.

Guests of the Rosneft pavilion at the “Russia” exhibition and forum were able to learn a lot about amazing creatures - walruses. Researcher at the A.N. Severtsov Institute of Ecology and Evolution RAS Svetlana Artemyeva gave an educational lecture to the guests of the pavilion, during which she spoke about the process of scientific expeditions, about the peculiarities of the life and behavior of walruses, as well as about their favorite habitats. Three interesting facts from the lecture: - During the expeditions, detailed mapping of known walrus rookeries was carried out.- During the one-time “census” of walruses, more than 7,000 individuals were recorded for the first time.- The largest concentration of walruses was discovered on the island of Eva Liv - more than 2000 animals. At the end of the event, there was a thematic quiz dedicated to marine mammals. The winner of the quiz received a unique book “Rediscovering the Arctic”, dedicated to the 10th anniversary of Rosneft’s research in the Arctic. If you want to learn more about how Walrus Day went at the company’s stand, visit the website. Photo and video: Rosneft

Figure 1. Formed F. gardneri embryos before emerging from the eggs. (a-c) appearance; (d) cartilaginous skeleton; (e) bony skeleton; (f,g) muscles. Annular (annual or seasonal) fish of the killifish group from the order Cyprinodontiformes are widespread in the tropics, where they often inhabit small drying up reservoirs. These fish stand out among all vertebrates for their unique ability to fall into states of embryonic diapause - a temporary phenomenon of complete or partial stoppage of development and metabolism of the embryo. Killifish are characterized by a short (usually less than a year) life cycle, and their embryos are exceptionally resistant to negative environmental factors. During periods of drought, killifish eggs remain viable for several months or even years in the ground. These features make killifish popular model objects for studying vertebrate diapause, the biology of aging, stress tolerance, and life history evolution. Many comparative studies often use a popular aquarium species, the West African steelhead Fundulopanchax gardneri, as a popular model for “out-of-season” killifish. However, its development has been largely unstudied, and it remains unclear whether it involves diapauses. Figure 2. Diagram showing the results of factor analysis. The size of the markers is proportional to the number of somites in the embryo. Individuals with “fast” (green) and “slow” (red) developmental trajectories initially do not differ in head size with a small (< 15) number of somites (third quarter of the graph) and begin to differ significantly when more than 15 somites are formed. For the first time, we studied in detail the embryonic development of the steel-blue aphyosemion, focusing on the formation of somites, sensory organs, skeleton, color pigments, muscles and the circulatory system (Fig. 1). It was found that in the early ontogeny of F. gardneri, there are one or two facultative arrests of developmental processes, similar to those for the unconditionally annual killifish species Austrofundulus limnaeus. Embryos of the same age and from the same clutch of eggs can differ significantly in body size and appearance, demonstrating “fast” (with direct development) and “slow” (with diapauses) ontogenetic trajectories (Fig. 2). Such a difference is of great biological importance for survival: hatching from eggs occurs at different times, which increases the chance that at least some of the fry will find themselves in environmental conditions favorable for survival. However, compared to A. limnaeus, these stops appear more like “less pronounced” versions of diapause and completely disappear with increasing water temperature. Thus, steel-blue aphyosemion appears to be more of an “intermediate link” between seasonal and non-seasonal killifish species. This finding supports the old hypothesis that F. gardneri is close to the ancestor of modern annual species. At the same time, recognition of F. gardneri as a representative annual/nonannual model seems premature. The work was published in the authoritative scientific journal “Developmental Dynamics”. V. Borisov, F. Shkil, D. Seleznev, S. Smirnov. (2023). Is African non-annual killifish Fundulopanchax gardneri (Teleostei; Cyprinodontiformes; Nothobranchiidae) true non-annual? DOI: 10.1002/dvdy.668

© RIA News / Maxim Deminov Ilya Mordvintsev, candidate of biological sciences, leading researcher at the Institute of Ecology and Evolution of the Russian Academy of Sciences, spoke about the preliminary results of the program this year and plans for the next period. In September, scientists conducted aerial research from a Mi-8MTV helicopter. Experts assessed the frequency of occurrence, distribution and condition of polar bears during the ice-free period on Bely Island and the coast of the Yamal Peninsula. "Meetings of 10 single individuals were recorded. An adult male polar bear was caught on the island, a set of biological samples was taken and morphometry was carried out,” said Ilya Mordvintsev. From July to August, during the expedition “Arctic Floating University - 2023”, organized by the Northern (Arctic) Federal University (NAFU), ship and helicopter observations of encounters and distribution of polar bears and their food sources were carried out on the helicopter-carrying scientific expedition vessel (RV) “Mikhail Somov”. From July 4 to August 16, encounters of 11 bears were recorded on the islands of Franz Josef Land, Vaigach, Uedineniya and the coast of the Yenisei Bay. “Our employees conducted round-the-clock surveillance to register not only polar bears, but also all marine mammals encountered along the route of the RV Mikhail Somov. In addition, we conducted lectures and seminars for students of the Arctic Floating University,” the scientist noted. A comprehensive joint expedition of the Russian Geographical Society and the Ministry of Defense with the support of the Russian Arctic National Park also took place in September. Experts conducted field route observations to assess the occurrence and condition of polar bears on the island of Alexandra Land in the Franz Josef Land archipelago. This year’s results indicate a high number of animals on land during the summer ice-free period and the good condition of bears in the areas where we were able to work, emphasized Ilya Mordvintsev. “This year, for a number of reasons, we were unable to carry out one very important expedition to the Bear Islands archipelago in the East Siberian Sea, so plans for 2024 include continuing polar bear research on the islands of this archipelago and the coast of the Nizhnekolymsky region of Yakutia, which were started us in 2022,” he said. Related materials: Arctic Universe: "Summary of preliminary results of the polar bear program for the current year"