Spatio-temporal distribution of species shapes community structure and ecosystem function, yet the mechanisms driving biological hotspots remain unclear in dynamic environments like sea ice. We computed Getis-Ord (Gi*) distribution hotspots based on four years of direct and indirect observations of polar bears (Ursus maritimus), Arctic foxes (Vulpes lagopus), ringed seals (Pusa hispida), and bearded seals (Erignathus barbatus) in western Hudson Bay, to identify spatial clustering and assess spatial relationships among these ice-associated species. We further mapped distribution hotspots of bear-hunting sign to examine predator-prey and intraguild relationships. Polar bears and bearded seals primarily used offshore areas, while Arctic foxes concentrated their activity on nearshore ice. Ringed seals built lairs throughout the study area but they mostly hauled out on landfast ice. The polar bear hotspot overlapped largely (30% - 49%) with those of the three other species. Particularly, 80% of the Arctic fox hotspot was included in the polar bear hotspot. In contrast, bearded seals and ringed seals had low overlap (18%), reflecting their different habitat preferences. Understanding current patterns in ice-associated species' distributions and relationships is crucial to inform conservation actions and for predicting direct and indirect effects of Arctic warming. Our results help identify key ecological areas on sea ice and demonstrate how systematic collection of opportunistic observations can be combined to generate valuable ecological insights at low cost.

Conventional vibration monitoring techniques for cantilever beams suffer from several limitations, including physical contact requirements, installation complexity, degradation over time, and susceptibility to environmental noise. Photodiodes, while commonly used in optical sensing, are typically assumed to exhibit uniform responsivity. Additionally, traditional approaches offer limited scalability for real-time, non-invasive, and predictive maintenance solutions. This paper presents a novel vibration analysis technique that exploits the non-uniform spectral responsivity of photodiodes to detect beam oscillations without physical contact. When a vibrating cantilever beam reflects a laser spot across the photodiode surface, spatial variations in light incidence produce voltage fluctuations that are recorded using a digital storage oscilloscope. Experiments conducted on different cantilever beams reveal that the proposed method accurately determines natural frequencies. To enhance diagnostic accuracy, the voltage signals are processed using a Deep Learning Model, Sentiment Cross-Fusion Network (SCFN), optimized with the Improvised Arctic Fox Algorithm (IAFA). Among competing models, the sentiment cross-fusion network achieved the highest classification accuracy of 0.90%. The improvised arctic fox algorithm further improved prediction performance, achieving 92.1% accuracy, with the lowest error values of root mean square error (0.10) and mean absolute error (0.07). The proposed framework demonstrates excellent potential for real-time, scalable, and accurate structural health monitoring in civil and industrial applications, although considerations like photodiode alignment and active area limitations must be addressed for broader deployment.

One of ecology’s major challenges is explaining how animal populations fluctuate in time. We tested whether reduced reproduction was a contributing cause of a cyclic decline in a collared lemming (Dicrostonyx groenlandicus (Traill, 1983)) population in northern Canada. The decline began in autumn and winter (1996/97) and continued the following summer (1997). We concluded previously that predation was a primary cause of the summer lemming decline, and limited summer population density. Here we recorded changes in lemming reproductive condition and estimated winter predation on lemmings from predators’ functional and numerical responses. Most lemming reproduction stopped late in peak summer 1996 but recovered in decline summer 1997. Estimated winter predation during the decline was similar to summer radio-telemetry mortality estimates. We conclude (1) in autumn and winter, a decreased reproductive rate and increased predation by arctic foxes and avian predators before snowfall may have contributed to winter decline; (2) in summer 1997 reproduction recovered, hence a low summer reproductive rate was not a factor in the continuing decline. Winter declines from high collared lemming density may be driven by absence of winter reproduction, along with mortality caused by predation and harsh winter weather.

Members of the genus Trichinella are muscle-dwelling zoonotic parasites of global importance for public health, animal husbandry, and trade. Trichinella chanchalensis (T13) is the newest species in the genus, first described in the Yukon and the Northwest Territories, for which the geographical distribution remains unknown due to limitations of the gold standard test for genotyping (multiplex polymerase chain reaction [PCR]). Our primary objective was to determine whether T. chanchalensis was present in Alaska, using a new molecular method that enables the description of the prevalence, co-infection, host associations, and risk factors for Trichinella spp. infection in wild carnivores. Trichinella spp. larvae were recovered through artificial digestion of muscle and genotyped using next-generation sequencing (NGS). Trichinella spp. larvae were detected in 53/157 (34%) animals, namely wolverines (Gulo gulo), arctic foxes (Vulpes lagopus), red foxes (Vulpes vulpes), coyotes (Canis latrans), wolves (Canis lupus), brown bears (Ursus arctos), and polar bears (Ursus maritimus), but not in black bears (Ursus americanus) or lynx (Lynx canadensis). Prevalence was highest in polar bears and wolverines, while intensity (larvae per gram, LPG) was highest in red foxes, arctic foxes, and wolves. Most animals (65%) harbored single infections with Trichinella nativa, followed by mixed infections of T. nativa and Trichinella T6 (33%). A single wolverine was infected with T. nativa, T6, and T. chanchalensis. Combining NGS with statistical methods, we found no evidence of competition between T. nativa and T6 in host muscles. Trichinella spp. infection (primarily T. nativa) was the highest in the Northwestern region, whereas T6 infection probability was higher in the Interior and Southern regions, suggesting differences in environmental resistance even among these three taxa. In a single, highly infected brown bear, we detected a rare case of Trichinella spiralis of foreign origin based on whole-genome sequencing, suggesting illegal importation and disposal of meat. We report a new geographical record for T. chanchalensis and a rare finding of T. spiralis in North American wildlife, and demonstrate the utility of new NGS methods for describing the ecology of parasites maintained in wildlife hosts commonly presenting as co-infections.

This report describes highly pathogenic avian influenza virus (HPAI) H5N1 infections in carnivores in Alaska, USA between 2022 and 2024, including a black bear (Ursus americanus), a brown bear (Ursus arctos), and the first known report of HPAI in an ermine (Mustela ermina). The two bears were cubs, and the ermine was a young adult. The black bear and ermine were euthanized after demonstrating neurologic signs, including circling, blindness, ataxia, or seizures. The brown bear was found dead. Gross lesions included swelling and congestion of the brain in both bears. Microscopically, all three individuals exhibited severe, nonsuppurative necrotizing meningoencephalitis, which was most prominent in the gray matter. Nonneuropathic microscopic lesions shared between both bears were multifocal random hepatic necrosis with lymphoplasmacytic hepatitis and mild interstitial pneumonia with bronchitis. The spectrum of additional lesions in individual animals consisted of acute necrosis within multiple other organs, including skeletal muscle, pancreas, kidney, retina, adrenal glands, and intestine. Immunohistochemistry demonstrated positive staining within neurons and glial cells in the brain, enterocytes and neurons of the myenteric plexus in the intestine, rare bronchiolar epithelial cells, renal tubular epithelial cells, and myocyte nuclei. Two HPAI-positive red foxes (Vulpes vulpes) and one positive Arctic fox (Vulpes lagopus) with incomplete histopathology are briefly discussed, as they demonstrate potential for co-infections with HPAI and canine distemper virus or rabies virus.

Abstract Predator–prey interactions in natural communities are complex, with predators often exploiting multiple prey types and generating indirect interactions among them. Ecological theory has traditionally modelled these interactions using functional response models which are based on foraging rates, not energy transfers. This approach overlooks how the energy acquisition rate of a predator can alter its behaviour and, in turn, the strength of species interactions. Here, we integrate predator energetics into a functional response model to represent trade‐offs predators face when foraging on prey that vary in risk and abundance across heterogeneous landscapes. We compared model predictions to 20 years of prey species density and reproductive success data. The mechanistic model was parameterized for an Arctic tundra vertebrate community, where the Arctic fox feeds on cyclic lemmings and eggs of sandpipers (non‐risky prey) and gulls (risky prey that often nest in partial refuge like islands). In this system, predator‐mediated interactions generate apparent mutualism between lemmings and birds, but their strength varies between species, and the mechanisms underlying this interaction remain unclear. We found that fox energetic balance was highly related to lemming density, with a threshold of 89 lemmings km −2 required for a positive energetic balance. Model‐predicted gull nest acquisition rates were lowest on islands when the energetic balance of foxes was positive, and highest for nests on the shore when foxes were in deficit. The model that incorporated predator risk‐taking behaviour and energetic balance produced variation in gull hatching success that most closely matched empirical observations. We documented for the first time that a shift in predator energetic balance, triggering changes in attack and capture probabilities on a risky prey, can be a key mechanism underlying the apparent mutualism between lemmings and gulls. In contrast, for non‐risky prey, the indirect effect can be essentially driven by changes in predator movement. These findings highlight how prey characteristics can lead to different mechanisms behind similar indirect interactions. Taken together, our results indicate that mechanistic models integrating species traits, landscape features and energy‐dependent behavioural adjustments can improve our ability to quantify interaction strengths in natural communities. Read the free Plain Language Summary for this article on the Journal blog.

ABSTRACTHumans have relied on animal fur for centuries, yet fur farming only began recently during the mid‐19th Century. Little is known about this incipient domestication or the genomic processes involved. Domestication may involve founder effects, population bottlenecks and low population size, which, when combined with intense artificial selection, lead to inbreeding, a limited gene pool and reduced fitness. The arctic fox (Vulpes lagopus) has been farmed intensively since the early 1900s and has been artificially selected for economic phenotypes. We investigated the origin of these lineages and the genomic consequences of intensive farming by comparing the genomes of farmed and wild arctic foxes from across their range. Our research indicates recent inbreeding through long Runs of Homozygosity and reduced genomic variation in farmed foxes relative to their respective wild populations. We identified a coastal ecotype origin for all Fennoscandian farmed arctic foxes, aligning them phylogenetically with the wild Icelandic population, a geographically isolated and phenotypically distinct coastal lineage. The depleted genome‐wide heterozygosity and increased recent inbreeding in farmed fox lineages is consistent with a heavy consequence of domestication, shedding light on the demographic history and genomic consequences of human manipulation. We highlight the need for increased genomic investigations into fur farm populations to understand the incipient domestication process and uncover the cost of intense farming. The genomic consequences of domestication must be considered in the management of fur farms, with actionable steps needed to prevent descendants of escaped farmed foxes from polluting the gene pool in the wild through introgression.

Reference genome choice compromises population genetic analyses.

ABSTRACTGeneralist species that benefit from human impacts on terrestrial ecosystems and expand their distribution range can threaten biodiversity by outcompeting or predating on native specialists. This is exemplified by the northward expansion of the red fox onto the arctic tundra where this mesopredator threatens endemic arctic fox and ground‐nesting bird populations. Here, effective management efforts to control the expansion depend on understanding the spatiotemporal scales of red fox movement within the tundra, and on identifying habitats that provide food resources to red foxes. We addressed these needs by studying the geographic space use and habitat selection of 14 red foxes on the low Arctic tundra of Varanger Peninsula in Norway by means of GPS telemetry. Red foxes used large home ranges and were especially mobile during winter, partly owing to occasional movements beyond home range boundaries. Home ranges were significantly smaller near the marine coastline and at higher human land use intensities, likely owing to higher food availability. These habitat features were also selected for within individual home ranges, confirming the importance of these habitats to red foxes on the tundra. High mobility necessitates large‐scale culling efforts aimed at achieving long‐term reductions in red fox densities. However, localised and temporary effects may be achieved by aligning culling with periods of reduced red fox movement and breeding of vulnerable species in late spring and summer. Additionally, reducing food subsidies associated with human land use could mitigate the underlying drivers of red fox expansion, offering a more sustainable approach to management.

The total expanse of hunting territories in Yakutia covers approximately 241 million hectares, providing substantial potential for hunting activities, which are a vital component of both the region’s cultural heritage and economic framework. The fur-bearing mammal fauna in Yakutia includes species such as sable (Martes zibellina), fox (Vulpes vulpes), brown bear (Ursus arctos), wolf (Canis lupus), muskrat (Ondatra zibethicus), squirrel (Sciurus vulgaris), white hare (Lepus timidus), ermine (Mustela erminea), Siberian weasel (Mustela sibiricus), arctic fox (Vulpes lagopus), wolverine (Gulo gulo), lynx (Lynx lynx), American mink (Neogale vison). This study used data derived from winter route surveys, questionnaires completed by hunting service providers and state inspectors, and records related to hunting and commercial animal production. Among the species studied, the sable holds particular significance. The consistent level of sable harvesting, alongside an observed increase in its population, suggests the effectiveness of conservation measures implemented to protect this valuable species. The muskrat ranks second in terms of harvest volume and exhibits a notably low seizure rate of 1–2%. Despite a 62% increase in squirrel populations over the past decade, squirrels remain economically unviable targets due to their low market prices. According to winter route surveys, populations of all fur-bearing animals in Yakutia are gradually increasing. However, this trend is accompanied by a rise in predator populations, raising ecological concerns and requiring prompt regulatory actions, including population control. The underexploited potential of fur-bearing animals in Yakutia stems from low market prices, limited consumer demand, underdeveloped processing and marketing infrastructure, and insufficient information and training for hunters. Addressing these challenges requires a comprehensive government strategy involving financial support for hunting, advancement of innovative processing and marketing technologies, hunter training programs, and initiatives promoting locally sourced fur products. This integrated approach would ensure the sustainable, efficient use of Yakutia’s natural resources and the long-term viability of its hunting industry.

Predator use of resource subsidies can strengthen top‐down effects on prey when predators respond numerically to subsidies. Although allochthonous subsidies are generally transported along natural gradients, consumers can cross ecosystem boundaries to acquire subsidies, thereby linking disparate ecosystems. In coastal Arctic ecosystems, terrestrial predators like Arctic foxes (Vulpes lagopus) cross into the marine environment (sea ice) during winter to access marine resources. Arctic foxes kill seal pups and scavenge seal carrion (often remains from polar bear Ursus maritimus kills), especially when rodent abundance is low. Terrestrial predator use of marine subsidies may strengthen the top‐down control of tundra food webs, but this hypothesis remained untested. We evaluated tundra food web dynamics at the terrestrial–marine interface from an ecosystem‐level perspective by assessing: (1) how winter environmental conditions affect rodent abundance and marine subsidy availability, (2) the response of the Arctic fox population to this seasonal food variability, and (3) the subsequent effects of Arctic foxes on Canada goose (Branta canadensis interior) reproduction. Arctic foxes responded numerically to rodent abundance, which was positively related to snow persistence. Arctic fox abundance was positively related to polar bear body condition metrics, which were used as a proxy for marine subsidy availability. Canada goose reproductive success, in turn, was negatively related to Arctic fox abundance. Long‐term trends in goose reproduction and snow persistence also indicate an ongoing phenological mismatch between nesting initiation and spring onset. Our results reveal near‐term apparent competition between rodents and geese through a shared predator, Arctic foxes, contrasting with prior studies evaluating rodent–goose–predator relationships. Moreover, we establish a link between tundra and sea ice food webs by demonstrating how seal availability can affect goose reproduction indirectly by increasing Arctic fox predation on goose nests via a population response of foxes to marine resources. These marine resources are often provisioned by polar bears, and with both Arctic foxes and polar bears undergoing long‐term regional declines evidently driven by climate‐related changes in prey abundance and availability, we contextualize our study within ongoing climate change and highlight the vulnerability of this likely widespread terrestrial–marine linkage in a warming Arctic.

Between 7 June and 5 September 2025, 183 highly pathogenic avian influenza (HPAI) A(H5) virus detections were reported in domestic (27) and wild (156) birds across 15 countries in Europe. Although HPAI A(H5N1) virus detections were predominant in western and southwestern Europe, they also occurred on the northernmost coast of Norway. More than 75% of the detections in wild birds related to colony‐breeding seabirds, particularly European herring gulls, while the number of detections in waterfowl decreased compared to the previous months. Less poultry establishments were affected during the current reporting period, with no secondary spread occurring. Regarding mammals in Europe, HPAI A(H5N5) virus detections were reported in four Arctic foxes in Norway. In the United States of America (USA), the number of HPAI A(H5N1) virus detections in dairy cattle stagnated, while the muskrat and round‐tailed ground squirrel were reportedly affected for the first time. Between 7 June and 8 September 2025, 19 cases of avian influenza virus infection in humans, including three deaths, were reported in four countries: Bangladesh (one A(H5N1) case), Cambodia (11 A(H5N1) cases), China (one A(H10N3), five A(H9N2) cases) and India (one A(H5N1) case). Most of the A(H5N1) human cases (n = 12/13) reported exposure to poultry prior to detection or onset of illness. Given the widespread circulation of avian influenza viruses in animal populations, human infections remain rare. No human‐to‐human transmission was documented during the reporting period. The risk of infection with the avian A(H5) clade 2.3.4.4b influenza viruses currently circulating in Europe remains low for the general public in the European Union/European Economic Area (EU/EEA) and low‐to‐moderate for those occupationally or otherwise exposed to infected animals or contaminated environments.

Birds generally rely on proactive anti‐predator strategies when selecting nest sites, as they have limited options to adapt to changing levels of risk once incubation begins. Arctic waterfowl often nest colonially as an anti‐predator strategy, but dispersed‐breeding species may use other proactive strategies, such as nesting in areas perceived to be safer. However, empirical links between spatial patterns of predation risk and nest habitat selection or success are needed to better understand how predator activity shapes Arctic waterfowl reproduction.Using activity data from the main cursorial nest predators, Arctic and red foxes (Vulpes lagopus, Vulpes vulpes), and aerial predators, we evaluate the influence predator activity has on Canada goose (Branta canadensis interior) nest habitat selection and success, and how nesting phenology mediates these effects.We compared habitat selection models fit to (i) goose nest locations and (ii) fox locations obtained from GPS collars and found that geese and foxes displayed nearly opposite patterns of selection for the same landscape traits. Geese selected sites that minimized their probability of encountering foxes while also maximizing their ability to detect foxes. Spatial predictions of fox activity revealed nests located in areas with higher probability of fox use had lower nest success, indicating fox space‐use patterns reflect predation risk.Landscape heterogeneity influenced both fox and goose nest habitat selection patterns and, consequently, spatial variation in predation risk and reproductive success. Aerial predators appeared to have a lesser effect on spatial patterns of goose nest habitat selection and success.Spatial patterns of nest success were, however, strongly influenced by nesting phenology. Nests initiated earlier had a greater probability of successfully hatching, but these patterns depended on location; the benefits of nesting early decreased in areas of high fox activity.Our study demonstrates the mechanisms by which nesting phenology, predator activity and landscape heterogeneity interact to shape bird reproduction and provides an empirical demonstration of how our understanding of predation risk is enhanced by integrating both spatial and temporal dynamics.

Abstract Demographic declines have important consequences for population viability, since they can lead to losses in genome diversity, as well as increased inbreeding and expression of deleterious mutations. Scandinavia was colonized by the Arctic fox (Vulpes lagopus) at the Pleistocene/Holocene transition, and the population has since been on the periphery of the global distribution. The Scandinavian population became even more fragmented in the early 1900s due to human persecution, and experienced an additional decline in the 1980s. We generated high-coverage genomes from pre-bottleneck, as well as modern Scandinavian and Russian specimens, and found that genome-wide diversity was lower and inbreeding higher in Scandinavia compared to the Siberian population, even prior to the historical bottleneck, most likely reflecting the long-term partial isolation and recent postglacial origin of the Scandinavian population. The southern subpopulation has the highest inbreeding levels, likely due to having been recently founded and highly isolated. Our results also show that although inbreeding increased substantially over the past century, the amount of total genetic load did not change. Overall, these findings illustrate the utility of a temporal approach to disentangle the genomic consequences of recent declines from ancient biogeographic processes.

This Scientific Opinion (SO) addresses a mandate from the EC regarding welfare of the following animals when farmed for their fur: (i) American mink (Neogale vison or Neovison vison), (ii) Red fox (Vulpes vulpes, also known as 'silver fox'), (iii) Arctic fox (Vulpes lagopus, also known as 'blue fox'), (iv) Raccoon dog (Nyctereutes procyonoides, also known as 'Finnraccoon') and (v) Chinchilla (Chinchilla lanigera). The request was to identify the most relevant welfare consequences (WCs) for each species and to determine whether these could be prevented or substantially mitigated in the current husbandry systems. 'Current system' refers strictly to the cage systems and cage dimensions as described in the EFSA Technical report produced under this mandate, as there was no or very limited information available on animals kept in alternative farming systems. Using information obtained from a review of literature, consultations with stakeholders and consideration by EFSA experts, the SO addresses for each species these WCs along with their underlying hazards and potential preventive or mitigating measures. In all species, Restriction of movement, Inability to perform exploratory or foraging behaviour, and Sensorial under- and overstimulation were selected as the most relevant WCs, sharing common hazards linked to current cage size and barrenness. Species-specific WCs include: soft tissue lesions and integument damage (mink), and handling stress (mink and foxes); locomotory disorders (Arctic fox); group stress (red fox), locomotory disorders and isolation stress (raccoon dog); and inability to perform comfort behaviour, resting problems and predation stress (chinchilla). In the majority of cases, it is concluded that neither prevention nor substantial mitigation of the identified WCs is possible in the current system. The SO also includes conclusions on limited or substantial mitigation measures in the current system and, when not possible, on substantial mitigating measures which would require a change to a different system.

Abstract This Technical Report was prepared in response to a mandate from the European Commission under Article 31 of Regulation (EC) No 178/2002. The request focused on updating the literature review from the 2001 report “The Welfare of Animals Kept for Fur Production” (SCAHAW, 2001), specifically addressing Section 4 (general aspects of carnivore biology—mink, foxes, and raccoon dog) and Section 5 (general aspects of rodent biology—chinchilla). Using information obtained from a review of literature, a call for evidence from stakeholders, field visits and consideration by experts in an EFSA working group, this report reviews the most up to date information on the species’ biology, production cycles, most common husbandry systems, including field‐tested systems, and farming practices used for the commercial fur production of the following species: i) American mink (Neogale vison or Neovison vison, previously classified as Mustela vison), ii) Red fox (Vulpes vulpes, and also known as 'silver fox'), iii) Arctic fox (Vulpes lagopus, previously classified as Alopex lagopus and also known as 'blue fox'), iv) Raccoon dog (Nyctereutes procyonoides, also known as ‘finnraccoon’), and v) Chinchilla (Chinchilla lanigera).

It is of interest for many linguists that in some languages animal coloration is described by colour terms that seem unusual at first glance, e.g. zelen konj in Serbian, голубой песец in Russian and blue fox in English, as there are no green horses or blue arctic foxes in nature. This issue is also relevant for the Yakut language, where not only horses (күөх бороҥ ат) and arctic foxes (күөх кырса) are associated with the blue-green colour through the colour term күөх ‘blue/green’, but also wolves (күөх бөрө), bulls/cows (күөх оҕус/ынах), squirrels (күөх тииҥ) and, presumably, the Yakut “green fox” (саһыл ‘fox’ < Old Turkic jašїl ‘green’). In order to explain the phenomenon, the author examined these lexical units using various linguistic research methods (lexicographic, component, cognitive and etymological analyses) and correlated them with objects of reality in synchrony and diachrony. Preliminary results demonstrate that in the cases under consideration, the Yakut colour term күөх expresses not a solid blue/green colour, but rather a grey shade of a complex, uneven coloration, which can be explained etymologically as a result of the complex semantic evolution of the syncretic Proto-Turkic *gȫk ‘sky; any colour of the sky; green, light blue, blue, blue-grey’. When it comes to the Yakut fox, it is probably “green” due to the fading of the green colour (light green – yellow-green – yellow – yellow-grey), similar to the colour of withered grass when animal fur is compared to grass.

Abstract Just before World War I, the Hudson’s Bay Company (HBC) geographically expanded its trade in the Canadian Arctic to derive profits from Arctic fox fur and secure its position in a global value chain (GVC) delivering fur to metropolitan consumers. The “problem of nature” challenged the company’s business venture. Furthermore, “nature” was made and remade by the HBC’s own capital investments. The fox trade itself changed human ecology. Technology transfers to Inuit modified their hunting regimes to increase the company’s returns of polar bear skins. Though these skins had high potential market value, modes of production introduced by the HBC to the Arctic precluded the company from sending high-quality products to metropolitan dressers. Within a changing Arctic human ecology, the HBC produced one highly valued commodity for the market while producing another from which it could derive only modest profit. The HBC’s fox and polar bear trade at the onset of the last century suggests ways that business empires can set off complex and unanticipated changes in human ecologies and, therefore, the dynamics of nature and business at their very peripheries.

The article presents the results of the pathological examination of the corpse of an arctic fox delivered from Copper Island (Commander Islands). Due to the sharp depression of the unique population of the Mednovsky (commander) Arctic fox – the only predator of Medny Island and the key element of the local ecosystem, the preservation of this subspecies is an urgent task for researchers. Parasitic diseases are widespread in arctic foxes and researchers consider arctic fox helminthiasis as one of the possible limiting factors in population depression. In this connection, the purpose of our study was to analyze pathological changes in organs and tissues, including parasitological research, which entailed the cause of death of the animal. The work was carried out at the departments of pathological anatomy and forensic veterinary medicine, pathological physiology and parasitology named after V.L. Yakimov FSBEI HE SPbGUVM. According to the results of the postmortem autopsy of the animal, signs of alimentary dystrophy, as well as acute catarrhal erosive gastritis with hemorrhage to the stomach cavity were found. According to the results of parasitological research, 11 adult nematodes of red color, 40–60 mm long, were found in the tumor-like granuloma of the gastric wall and in its cavity. Morphological data and localization of nematodes gave reason to identify them up to the river. Spirocerca. Previously, about the finds of helminths p. Spirocerca in arctic foxes Copper Island did not communicate.

The article presents the results of a parasitological study of scrapings from the skin of the inner surface of the auricle, scalp, back, side surfaces, front and hind limbs, hair with epidermal scales of the corpse of Arctic fox puppy (Vulpes lagopus semenovi Ognev) at the age of 3-4 months, delivered from Medny Island, which is part of the Commander Islands (Russia). At the Department of Parasitology named after V.L. Yakimov of the St. Petersburg State University of Veterinary Medicine biological material was placed in 50% glycerin and examined by light microscopy using a Primo Star Zeizz microscope (Germany) under magnification of 40 and 100. Microscopy revealed acariform mites in all phases of development: egg, larvae, nymphs and adults. According to morphological features, such as: body shape, limb length, location of ambulacres on them, structure of the gnatosome, ticks are identified to the genus Otodectes. Microscopy of scrapings from the scalp, back, lateral surfaces, front and hind limbs of the arctic fox and wool with epidermal scales revealed ticks with morphological features characteristic of the genus. Otodectes. In the scrapings in the field of view at 40-fold magnification, the number of ticks ranged from 12 to 20 and indicated a high intensity of invasion. Since skin-eating ticks, including otodectes, have high specificity for the localization site, therefore, the detection of ticks of the genus. Otodectes in places of localization not specific to them is interesting in order to study their species affiliation. The purpose of further research will be a genetic analysis of ticks found on the surface of the arctic fox body to confirm the validity of the species parasitizing in carnivores - O.cynotis.