Camera Trap Distance Sampling (CTDS) enables population density estimation of unmarked species from camera trap data by incorporating animal-to-camera distances. In this study, we systematically evaluate the sensitivity of CTDS-derived density estimates to variation in key pipeline parameters, using a high-resolution camera trap dataset from Central Europe. Over a 12-month period, 110 cameras were deployed across a forested area of 94 km 2 . Animal-to-camera distances were estimated via monocular depth estimation. To reduce manual annotation effort, we introduce an automated masking approach for calibration images based on the Segformer model, saving an estimated minimum of two minutes per image. Using red deer ( Cervus elaphus ) as model species, a full-factorial sensitivity study (n = 135 parameter configurations) was conducted, varying MegaDetector confidence threshold, depth sampling method, mean trigger intervals and right-hand distance truncation schemes. Results show that population density estimates are highly sensitive to the choice of depth sampling method, MegaDetector confidence threshold and mean trigger interval. Parameter-induced variation led to differences of up to 200% in population estimates relative to the lowest estimate, twice as much as the variation observed between spatial subsets of the study area differing in vegetation characteristics. However, relative differences between the two sub-areas remained largely consistent across configurations. These results highlight the critical impact of technical choices within CTDS workflows and emphasize the need for transparent reporting and standardization of key pipeline parameters. All CTDS analyses using automated pipelines should therefore be accompanied by dataset-specific sensitivity analyses to account for parameter uncertainty and validation challenges. Overall, our study demonstrates both the methodological challenges and practical applicability of automated CTDS for large-scale wildlife monitoring. • Automated masking reduces manual effort in depth calibration by ∼ 2 min per image. • CTDS parameter variation caused 200% difference, twice our spatial density variation. • Depth sampling, confidence thresholds and trigger intervals affect density estimates. • Automated CTDS requires standardization and dataset-specific sensitivity analyses.

Tick-borne pathogens pose significant threats to wildlife health and may serve as sources of zoonotic infections. This study aimed to investigate the occurrence of Anaplasma spp., particularly Anaplasma ovis, in blood and tick samples from wild goats (Capra hircus aegagrus) and Caspian red deer (Cervus elaphus maral) in East Azerbaijan Province, Iran. A total number of 135 ticks and 59 blood samples were collected from live-captured and deceased animals. Molecular detection was initially performed using PCR to identify the genus Anaplasma. Subsequently, gene sequencing and phylogenetic analysis were conducted to determine the species Anaplasma. Positive blood samples were examined microscopically with Giemsa-stained smears. Key findings: In ticks from wild goats, A. ovis positivity was 6.52% and Anaplasma spp. 9.78%; corresponding rates in ticks from red deer were 4.65% and 6.98%. Blood samples were positive for A. ovis only in wild goats (11.11% prevalence), with all red deer blood samples negative. Anaplasma ovis DNA was detected in blood from one deceased wild goat, but this does not imply causality with mortality, given the typically mild nature of infections. Phylogenetic analysis confirmed strain identities and relationships with known sequences. These descriptive results revealed apparently higher detection rates in wild goats compared to red deer, suggesting species-specific differences in exposure or susceptibility. This study highlighted the role of wild goats as potential reservoirs of A. ovis in the region. This study highlighted the need for systematic surveillance of tick-borne pathogens in Iranian wildlife populations.

Abstract The transition from the Last Glacial Maximum to the Late Glacial marked a shift from the cold conditions of Greenland Stadial‐2 (GS‐2) to the warmer phases of Greenland Interstadial‐1 (GI‐1), enabling the reoccupation of Alpine regions by Late Palaeolithic hunter‐gatherers. Riparo Tagliente, a rockshelter in northeastern Italy, preserves the most extensive Late Glacial stratigraphy in the southeastern Alps and provides key evidence for early human re‐settlement by Late Epigravettian groups. To investigate environmental conditions and resource stability, we analyzed stable carbon and oxygen isotopes ( δ 13 C carb , δ 18 O carb ) in enamel carbonate from red deer ( Cervus elaphus ) second and third molars across stratigraphic units 13 to 5, spanning GS‐2.1a to GI‐1. Tooth δ 13 C values reflect a diet based on C3 plants within relatively open woodland environments, showing limited change across climatic transitions. Intra‐tooth δ 18 O profiles record seasonal conditions, summer in M2 and winter in M3, and were used to estimate past temperatures. Reconstructed mean monthly winter temperatures reached −3.1°C in layer 10, with summer temperatures rising to ~16°C in layer 9 during GI‐1. These results highlight environmental continuity in red deer ecology despite climate fluctuations, suggesting that stable, open habitats supported sustained human use of the site throughout the Late Glacial.

A simple, fast, and cost-effective organic solvent-based protocol was developed for DNA extraction from deer antlers and prepared trophy skulls, eliminating the need for commercial kits or cryogenic grinding. The method combines bead-based mechanical homogenization with a 4 h enzymatic digestion in EDTA buffer containing N-lauryl sarcosine and Proteinase K, followed by phenol-chloroform-isoamyl alcohol purification and centrifugal filtration. DNA quality and quantity were evaluated using agarose gel electrophoresis, Qubit fluorometry, and Nanodrop spectrophotometry. The protocol was tested on 60 samples, comprising 30 antlers and 30 pedicle parts from prepared trophy skulls of roe deer (Capreolus capreolus), fallow deer (Dama dama), and red deer (Cervus elaphus). To assess suitability for downstream applications, species-specific microsatellite markers were amplified using multiplex PCR, successfully generating complete genotypes from all 60 samples. These results, along with a demonstrated case study, confirm that the developed protocol provides high-quality DNA suitable for molecular genetic investigations, enabling reliable genotyping from small amounts of both antler and processed trophy materials in forensic and conservation contexts.

Onchocerca flexuosa is a vector-borne filarial nematode infecting red deer (Cervus elaphus) throughout Europe. Despite numerous reports from Central, Northern, and Southern Europe, its occurrence in South-Eastern Europe has remained largely undocumented. This study provides the first molecularly confirmed report and the first systematic epidemiological assessment of O. flexuosa in red deer in Croatia. During the 2024-2025 hunting season, 110 legally harvested red deer from central Croatia were examined for subcutaneous nodules. Nodules were evaluated morphologically, and adult nematodes were identified and confirmed by sequencing of a fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene. Subcutaneous nodules were detected in 53.6% (59/110) of examined animals. O. flexuosa was confirmed in 52 deer, corresponding to an overall prevalence of 47.3%. Co-infection with Hypoderma diana occurred in 21.2% of infected animals. Sequence similarity ranged from 96.37% to 99.85% compared to published European O. flexuosa isolates. Phylogenetic analysis placed Croatian sequences within the established European lineage, without evidence of regional genetic divergence. The observed prevalence falls within the intermediate range reported across Europe and indicates stable local transmission. These findings close an important geographical knowledge gap and demonstrate that nodular onchocercosis is established in red deer populations in South-Eastern Europe.

The Carpathian Basin is a coherent biogeographic unit whose wildlife populations and pathogen dynamics are increasingly reshaped by administratively fragmented governance, land-use change and linear infrastructure. This review synthesizes evidence that the permeability patterns governing host movement also structure the transboundary exchange of genes and infections, creating a connectivity substrate for conservation genetics and One Health risk. Focusing on wild boar (Sus scrofa), red deer (Cervus elaphus), roe deer (Capreolus capreolus), fallow deer (Dama dama) and the expanding golden jackal (Canis aureus), we integrate population genetic inferences with wildlife epidemiology to examine how highways, border fences and asymmetric management (e.g., supplemental, feeding practices, hunting pressure and surveillance regimes) can generate biological asymmetries across boundaries. We highlight African swine fever as an emblematic disturbance in wild boar populations, discuss cervid risks including tick-borne pathogens and chronic wasting disease (CWD) preparedness and evaluate zoonotic threats associated with carnivore expansion (e.g., Echinococcus spp.). We propose a Carpathian Basin-level monitoring and data-sharing architecture, coupling harmonized passive surveillance, strategic active surveillance for priority pathogens, and standardized genetic marker panels supported by interoperable metadata. A Basin-scale One Health approach is a pragmatic prerequisite for the coordinated prevention, early detection and resilient management of cross-border epizootics and zoonotic threats.

Fascioloidosis is a parasitic disease caused by allochthonous parasite Fascioloides magna. In Europe, three types of final hosts are recognised: definitive, aberrant, and dead end. Several countries have launched disease control programmes using medicated feed, with different drugs, to control F. magna infections. In this study, we used corn treated with Albix® 10 in a total dose of 60 mg/kg of body weight for five consecutive days (12 mg/kg per day). Following successful treatment, a destroyed pseudocyst with different amounts of degrading material and decaying flukes was detected. A total of 136 livers was examined. The average number of pseudocysts per positive liver was seven (min. 1-max. 45), while the average number of adult flukes was 14.17 (2-70). On average, 1.34 juvenile flukes in the migratory phase were detected per infected liver. The average number of pseudocysts was 7.07 per liver in total. Degrading pseudocysts were either absent or present to a maximum of 120 per liver, with an average of 7.99 per liver. Some livers had multifocal to confluent nodules bulging from the liver parenchyma, which were up to 7 cm in diameter. Histologically, these areas showed disruption, containing bands of fibrous connective tissue, dividing parenchyma into pseudolobules of varying size and shape. These septa contained dark brown to black pigment (iron porphyrin), along with remnants of elliptical, operculated, mainly empty trematode eggs. Nodules were surrounded with fibrous tissue and disorganised hyperplastic hepatocytes arranged in irregular trabeculae supported by fibrous bands occasionally containing blood vessels. This study shows the potential of liver regeneration in the case of acute and chronic liver injury, as well as in cases of fatty liver disease.

Satellite-derived vegetation indices provide a powerful means to quantify habitat variation in long-term ecological studies, but their reliability as proxies for forage availability in wild herbivore populations remains underexplored. We used three decades of Landsat satellite imagery (1991-2023) to generate a 30 m resolution dataset of a proxy for annual vegetation greenness - the Normalised Difference Vegetation Index (NDVI) - for the Isle of Rum, Scotland, home to a long-term study of wild red deer (Cervus elaphus). We ground-truthed the NDVI data against live vegetation biomass data collected from calcareous grassland, which is preferred by the deer, and compared it with a coarser-resolution (500 m) MODIS Enhanced Vegetation Index (EVI) metric. Landsat NDVI was positively correlated with both live biomass and EVI, supporting its ecological relevance as a measure of forage availability. All three metrics have increased over the last three decades, indicating a long-term greening trend, with the higher resolution Landsat dataset revealing variation in the rate of change among vegetation groups, including grassland habitats preferred by deer. These findings suggest an increase in forage availability over time, which may have important consequences for the red deer on Rum. Our approach provides a transferable framework for integrating satellite data with individual-based field studies, demonstrating how remote sensing can enhance ecological inference in long-term wildlife research.

Central Europe faces an overabundance of wild ungulates, which is driven by several factors, including traditional hunting practices. The harvest of females is insufficient and recorded without verification, even when they were not actually hunted. This practice contributes to further population growth through accurate hunting records. Therefore, basic procedures for automated registration based on muzzle pattern animal biometric evaluation of harvested wild ungulates were proposed. The red deer (Cervus elaphus) served as the model species. For the assessment of biometric characteristics, 2,193 photographs were taken from the frontal and overhead directions of 972 harvested red deer during regular game management. A comparison of the collected images using the LoFTR (Local Feature TRansformer) method revealed the potential for individual identification, with the peak accuracy of 95.048%. On the contrary, the minimum accuracy was 90.048% using a combination of overhead and frontal images of high and medium quality. Because there is no solution for the recognition of ungulates the comparison of these results was performed with the recognition systems for pets and livestock. Achieved accuracy is around 2% better than comparable recognition systems (with similar dataset size, number of feature points, etc.). The results confirmed that biometric methods can be used to identify and record harvested game. This can be achieved by developing a mobile application that transmits images for automated comparison and evaluation. Once individual identity is confirmed, the animal will be registered. This ensures a verifiable record of harvested game and provides a solid foundation for sustainable hunting planning.

Norway spruce Picea abies is an economically important tree species in Europe, actively managed for forestry. Among the most negative biotic factors for growth and hence forest production is damage caused by wildlife, such as damage through bark stripping by red deer Cervus elaphus . We quantified bark stripping damage on Norway spruce trees in across 450 stands (aged 20–72 years) spanning a 400 km latitudinal range along Norway's west coast and analysed the underlying mechanisms driving increased probability of bark stripping by red deer. A total of 74% of tree stands had bark stripping damage. The mean percentage of damaged trees was 16.0%, but 50 stands (11.1% of the stands) had more than 50.0% damaged trees. The most important factor determining probability for bark stripping was broad‐scale red deer density, where the probability increased markedly when density reached approximately two harvested red deer per km 2 . In addition, proximity to agricultural farmland, distance from roads, site productivity, distance between twig whorls and terrain ruggedness index increased the probability of bark stripping. Our study on bark stripping on Norway spruce highlights the importance of red deer population control, but also the importance of evaluating environmental factors as well as site factors and tree characteristics in forestry planning to mitigate damage from red deer.

Epizootic haemorrhagic disease virus serotype 8 (EHDV-8) emerged in southern Europe in 2022-2023, but clinical and pathological characterization in free-ranging wildlife remains limited. This study investigated EHDV-8-associated morbidity and mortality in wild ruminants in a 2023 outbreak in Sierras de Cazorla, Segura y Las Villas Natural Park (Jaén, Andalusia, Spain). Moribund animals demonstrated a consistent acute neuro-respiratory syndrome characterized by weakness, ataxia, nystagmus and severe dyspnoea with frothy oral discharge. On the carcasses of 39 red deer, two fallow deer, and one mouflon, necropsy was performed and subsequently histopathology and a real-time polymerase chain reaction (RT-PCR) on the collected samples. Gross lesions included marked pulmonary oedema, tracheal foam and widespread congestion, while histopathology revealed lymphoid depletion, pulmonary haemorrhage, vascular injury and renal tubular necrosis. All animals tested positive for EHDV-8 with low RT-qPCR cycle threshold values, indicating high viral loads. This series provides the first confirmed clinical, pathological, and molecular evidence of EHDV-8 infection in fallow deer and mouflon in Europe. The observations demonstrate that EHDV-8 causes a peracute systemic haemorrhagic disease in susceptible wild ruminants and underline the importance of integrated wildlife surveillance and timely diagnostic sampling during peak vector activity.

Lungworms from the genus Dictyocaulus are known to cause catarrhal bronchitis and pulmonary atelectasis in domestic and wild ruminants. In red deer (Cervus elaphus), four Dictyocaulus species can be present in the respiratory tract. This study describes the investigation of mortalities in red deer (Cervus elaphus) in a commercial farm for red deer from Romania, associated with the presence of lungworms. Postmortem examination revealed the presence of nematodes in the bronchial lumen in all cases. Morphological and molecular examination of the nematodes recovered confirmed Dictyocaulus cervi as the species involved. The most probable cause of death in all four cases was respiratory failure due to the severe parasitic infection and cachexia. This study represents the first report of mortality associated with Dictyocaulus cervi in farmed deer and the first report of the species in Romania, highlighting the need for further epidemiological studies to assess its distribution and potential impact on other cervids in the country.

Precise and accurate information about population density, crucial for wildlife management, is difficult to obtain for elusive species living in dense forests or steep and inaccessible terrain. Using unmanned aerial vehicles (UAVs), we developed a method for obtaining absolute population estimates of ungulates living in steep, rugged, and partly forested terrain. The UAVs were used to collect data from four different case study areas in two consecutive months in winter/early spring (before leaf growth) in Lærdal, Norway. The detections of red deer Cervus elaphus from UAV images were done using a double observer protocol, and hierarchal state–space models were fitted to the data using a Bayesian framework to obtain posterior distributions of absolute deer density. Results indicate that availability bias was negligible when deer can be searched for in multiple UAV images of the sites (sample plots) taken from different angles by a UAV at 60 m above ground level but detection probability in the images was significantly below one and must hence be accounted for. Although the credible intervals were rather wide, our results demonstrate that absolute red deer density estimates with quantifiable uncertainties can be produced using this method. Lower credible limits for the estimates indicate that densities in two of the study areas were consistently well above management target densities during the two consecutive months. The high spatial variation in deer densities (at various scales) in our study pose a major challenge, as large areas with a high number of sampling sites must be covered to model the spatial variation and obtain reliable and precise density estimates at a scale relevant for management. We nevertheless conclude that the method has potential for reliable spatiotemporal deer density estimation, given sufficient resources and field efforts.

Winter enclosures are an important wildlife management tool in mountainous regions of Central Europe. They are implemented to reduce browsing pressure and bark peeling caused by red deer ( Cervus elaphus ) during winter by lowering their numbers in the surrounding landscape. However, the enclosures require high levels of maintenance and increase local animal densities, which could potentially enhance the spread of diseases and parasites. Therefore, it is of great interest to evaluate the effectiveness of winter enclosures in restricting red deer movement and minimizing browsing damage. Thus, this study employs an experimental approach to analyse the impact of winter enclosure management on these two parameters in the Bohemian Forest Ecosystem. Three treatments were implemented: (1) four winter enclosures kept closed (regular management), (2) four winter enclosures opened earlier (opened earlier), and (3) two winter enclosures left open all winter (open fences).The median winter home range of red deer increased sixfold under the open fences treatment compared to the previous year, though the home ranges still did not extend beyond the borders of the protected area. At the same time, browsing probabilities for all tree species decreased in the vicinity of the enclosures in the open fences treatment. No change in browsing probability was observed around the enclosures opened earlier compared to the previous year. These results suggest that the main factor contributing to changes in browsing pressure caused by the experimental treatments was that red deer overwintering outside the open fences enclosures gained access to supplementary feeding in winter, consequently reducing their browsing activities in the vicinity of these enclosures. Therefore, winter enclosures may not always outperform unfenced feeding stations as a management tool to reduce browsing pressure. • Winter enclosures confine red deer during winter and spring. • Our treatments allowed animals to leave earlier in spring or at all times (open fences). • Winter home ranges increased six times when fences were opened. • Nevertheless, browsing pressure decreased near open fences enclosures. • Winter enclosures are not always the most effective tool for browsing mitigation.

Since its first description in southern Spain, Lipoptena andaluciensis (Diptera: Hippoboscidae) has drawn increasing attention due to its uncertain origin and distribution. In this study, we report new records of L. andaluciensis from geographically distant regions, including the Castelo Branco district in Portugal and three different northern Spanish provinces (Lérida, Tarragona, and Aragón). A total of 26 specimens, identified as unwinged L. andaluciensis based on morphological traits and COI barcoding, were collected between 2022 and 2024 during several field surveys on red deer (Cervus elaphus) and roe deer (Capreolus capreolus). Additionally, Lipoptena cervi and Hippobosca equina were also collected on hosts. These recent records, indicate that the species may have been previously overlooked or misidentified, underscores the need for enhanced taxonomic resolution and expanded surveillance. To facilitate accurate identification, we provide a pictorial key to distinguish among the six European Lipoptena species, with special emphasis on Lipoptena fortisetosa, L. cervi, and L. andaluciensis. We also highlight the importance of combining detailed morphological and molecular analyses of both recent and historical specimens to prevent misidentifications and to better understand the biogeography of this emerging species.

Abstract Social connections affect important components of fitness above and beyond environmental or morphological effects. In some primates and carnivores, females live in stable groups, supporting each other in competitive interactions and breeding within their birth groups. Social status and breeding success are linked to close social connections. However, it is unclear how important social bonds are in open membership fission–fusion societies. Recent work suggests that the strength of social bonds and the centrality of individuals within groups in these types of societies might be equally beneficial and important as in closed-membership groups, influencing population dynamics on par with morphological or environmental effects. Using social network analysis, we studied free-ranging adult female red deer (Cervus elaphus) on the Isle of Rum, confirming that they preferentially associate with relatives while forming open groups. It turned out that the strength of close social bonds in female red deer is a vital fitness correlate. Females’ lifetime breeding success and lifetime reproductive success positively correlated with the strength of their associations, as did female survival. Although home range overlap, matriline size and spatial measures were included in models of social network measures and fitness, the strength of social bonds was more crucial for fitness than spatial variables, except for calf survival, which was not linked to the strengths of associations between females. This study suggests that social bonds among female red deer are essential for reproductive success and survival, highlighting the importance of social network analysis in understanding fitness correlates in species with open group structures.

Red deer (Cervus elaphus) populations are increasing in both number and range, raising concerns that parasite abundance, such as gastrointestinal nematodes, may be influenced by host density. Research exploring this relationship in wildlife remains scarce, particularly in Mediterranean ecosystems. This field study aimed to investigate the impact of red deer overabundance on gastrointestinal nematode parasitism in two Mediterranean areas: Quintos de Mora (central Spain) and Muela de Cortes (eastern Spain). We used four enclosures, comprising two overabundance scenarios: high density (~ 45–58 deer/km²) and hyper density (~ 93–106 deer/km²). Parasite burdens were initially assessed using individual fecal samples, revealing low nematode loads across all individuals. Parasite dynamics were then monitored through pooled fecal samples over a 15–18-month period, while deer diet composition was analyzed to provide ecological context. Nematode egg excretion declined over time in all enclosures, reaching undetectable loads in three enclosures by 11 months after deer introduction, regardless of host density. Diet analyses indicated a clear dominance of woody vegetation, accounting for up to 86% of the diet in Quintos de Mora and up to 68% in Muela de Cortes, while the proportion of graminoids remained minimal. This depletion of herbaceous structure and the dominance of tannin-rich woody species containing high antiparasitic properties could contribute to reduced low parasite loads. Additional work testing the hypothesis would benefit from increased replication and higher initial worm loads. Clinical trial number: Not applicable.

ABSTRACT Mammals play a crucial role in maintaining ecosystems through complex plant-animal interactions. Non-native mammals can disrupt these ecological relationships, affecting both native and non-native species. We examined the diet and seed dispersal of non-native mammals: red deer (Cervus elaphus), European hare (Lepus europaeus), and wild boar (Sus scrofa), focusing on their interactions with the invasive rosehip shrub (Rosa rubiginosa). We conducted a microhistological analysis of fecal pellets to identify diet components and assess seed viability. The mammals consumed 27 food items, predominantly native plants. However, the presence of nutritious rosehip fruits resulted in a high proportion of the diet and the dispersal of a large number of seeds. Wild boar, in particular, consumed the largest proportion of the fruits and was the main disperser of viable seeds. Our results indicate that non-native mammals act as vectors for the dispersal of viable rosehip seeds. This interaction could promote a positive relationship between invasive species, facilitating the spread of R. rubiginosa in accordance with the ‘invasional meltdown’ hypothesis. Identifying such invasive interactions provides insights for management strategies aimed at preventing or delaying the spread of invasive species in the natural ecosystems of Northwest Patagonia

This paper presents a new method for differentiating postcranial bone remains of red deer (Cervus elaphus), fallow deer (Dama dama), and roe deer (Capreolus capreolus) from European archaeological contexts. These species have very similar bone morphology and partly overlapping size ranges, often preventing species-level identification in zooarchaeological research. Traditional methods, such as the use of diagnostic morphological criteria, or aDNA analysis, present practical and methodological limitations. In this study, bone biometric data from modern specimens, sourced from various institutions across northern and southern Europe, are analysed to determine size ranges and shape indices that can separate the three species, focussing on both adult and immature individuals. By comparing measurement values from archaeological remains against these biometric criteria, species identification can be attempted. The low-tech nature of this approach and the transparent, diagrammatic presentation of biometric results make the new method objective and highly accessible. In European and Mediterranean historical archaeology, the species-level identification of cervid remains is crucial in the investigation of biogeography, trading activities, hunting strategies, cultural values, and social status.

Species interactions are crucial for understanding how species will respond to future climate change. Incorporating interspecific relationships into mammalian distribution prediction models will significantly impact model outcomes, especially those for animals on the Qinghai-Tibet Plateau (QTP). Thus, we incorporated interspecific relationships into species distribution models to assess and predict the future distributions of five ungulates, including the Red deer (Cervus elaphus), the Kiang (Equus kiang), the Tibetan gazelle (Procapra picticaudata), the Tibetan antelope (Pantholops hodgsonii), and the Bharal (Pseudois nayaur). We found that (1) the suitable habitats of these five ungulates were all predicted to increase between the present and 2050; (2) the suitable distribution areas of four of these ungulates were predicted to be smaller when interspecific relationships were incorporated into the models, with the exception of the Red deer, whose suitable habitat was estimated to be larger; and (3) the centroids of suitable habitat for the five ungulates were predicted to shift to the southern part of the QTP by 2050. Our results demonstrated that interspecific relationships could influence predictions of species distributions, and thus incorporating interspecific relationships will facilitate better assessments and predictions of the future distributions of species.