BMC Zoology最新文献

{"title":"Morphometrics, growth allometry, and condition status of the dark mahseer (Naziritor chelynoides) in a Nepalese hill stream.","authors":"Pawan Rana","doi":"10.1186/s40850-026-00294-y","DOIUrl":"10.1186/s40850-026-00294-y","url":null,"abstract":"<p><p>This study assessed morphometric and meristic variation, length-weight relationship, and condition indices of Naziritor chelynoides from the Chidiyar River, Nepal. A total of 128 individuals were collected from September to December 2025, including 43 specimens examined for detailed morphometric and meristic variation. The length-weight relationship showed significant negative allometry (b = 2.519; 95% CI = 2.33-2.71; R² = 0.841). Mean Fulton's condition factor (K) and relative condition factor (Kn) were both 1.01 ± 0.26. Principal Component Analysis showed that the first two components explained 34.377% of the total variance, with higher loadings associated with fin-base, head, and body-proportion variables. Meristic characters exhibited limited variation, while morphometric variation was continuous without visually apparent discrete groups. These results provide baseline biometric information for the sampled N. chelynoides population in the Chidiyar River and a reference for future spatial and temporal comparisons. Further studies across populations and seasons are needed to assess the consistency of these patterns.</p>","PeriodicalId":48590,"journal":{"name":"BMC Zoology","volume":"11 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13662999/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149185300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Splenic plasticity at the arid limit: dehydration is associated with microanatomical remodelling and B-cell depletion in the dromedary camel (Camelus dromedarius).","authors":"Mohamed Amine Fares, Aicha Mouane, Najah Elmounedi, Randa Mlik, Maria Chikha, Aziza Ferag, Mohammed Messaoudi, Ayomide Victor Atoki, Bernard Faye","doi":"10.1186/s40850-026-00284-0","DOIUrl":"10.1186/s40850-026-00284-0","url":null,"abstract":"<p><strong>Background: </strong>The dromedary camel (Camelus dromedarius) is the exemplar of mammalian adaptation to hyper-arid environments, possessing specialized physiological mechanisms to tolerate extreme osmotic stress and hemoconcentration. While renal and thermoregulatory adaptations are well-characterized, the costs of these survival strategies on immune microanatomy remain poorly defined. Structural remodeling of lymphoid organs may accompany hydric and metabolic stress in xeric specialists, but whether such changes represent adaptive reallocation or a nonspecific consequence of physiological stress remains uncertain. This study investigates the plasticity of the splenic marginal zone (MZ), a critical reservoir for innate-like B cells, under naturally occurring dehydration gradients.</p><p><strong>Methods: </strong>We conducted a cross-sectional morphophysiological study on C. dromedarius (n = 100) in the hyper-arid El Oued region of the Algerian Sahara. Hydration status was defined via serum osmolality and hematocrit. We utilized quantitative histomorphometry and immunohistochemistry to assess MZ thickness and B-cell density. Multivariable linear regression was employed to control for covariates (age, sex, body condition). We applied statistical mediation analysis to examine whether MZ remodeling statistically accounted for part of the association between dehydration and B-cell density.</p><p><strong>Results: </strong>Dehydrated camels exhibited significant splenic plasticity, characterized by a marked reduction in MZ thickness (157.9 ± 10.8 μm vs. 183.1 ± 9.6 μm in hydrated controls; p < 0.001) and a concomitant 24% decline in B-cell density. MZ atrophy was strongly correlated with systemic hydration markers (serum osmolality: r = -0.72). Mediation modeling indicated that 59% of the dehydration-B-cell density association was statistically accounted for by the MZ-thickness pathway (ACME: -196.2 cells/mm²). Furthermore, animals from the hyper-arid Sahara micro-region displayed greater MZ contraction than those from the transitional Sahel, suggesting environmental modulation of splenic architecture.</p><p><strong>Conclusions: </strong>These findings demonstrate marked dehydration-associated plasticity of the splenic MZ in the dromedary camel. The concurrent reduction in MZ thickness and B-cell density, together with their statistical association, identifies a previously undercharacterized relationship between systemic hydration status and splenic microanatomy. The present data do not establish that lymphoid remodeling is itself beneficial, adaptive, or specific to water deprivation; it may also reflect a broader physiological response to metabolic, endocrine, hemodynamic, nutritional, or other stressors. The findings therefore provide a basis for further investigation of the mechanisms and functional significance of splenic remodeling during dehydration.</p>","PeriodicalId":48590,"journal":{"name":"BMC Zoology","volume":"11 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13540909/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148867560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of livestock depredation by hamadryas baboons (Papio hamadryas) in and around Borena-Sayint National Park, northern Ethiopia.","authors":"Hussein Ibrahim, Afework Bekele, Dereje Yazezew, Amera Moges, Meseret Chane, Addisu Mekonnen","doi":"10.1186/s40850-026-00283-1","DOIUrl":"10.1186/s40850-026-00283-1","url":null,"abstract":"<p><strong>Background: </strong>As human populations expand and natural habitats become increasingly fragmented, the interface between agricultural activities and wilderness areas has become a focal point of ecological tension. Livestock depredation is a prevalent form of human-wildlife conflict, particularly in landscapes bordering protected areas. Beyond causing substantial financial losses for subsistence communities, these conflicts often generate negative attitudes toward wildlife, ultimately hindering long-term conservation efforts. Hamadryas baboon (Papio hamadryas) is distributed across diverse environments in Ethiopia, ranging from the lowlands to the highlands. Across its range, the species is known to prey on small livestock, particularly goats and sheep. Despite this, knowledge of human-hamadryas baboon interactions, especially those involving livestock depredation in the Ethiopian highlands, remains scarce. Therefore, this study aimed to gather data on the extent of conflict between hamadryas baboons and local communities in and around Borena-Sayint National Park (BSNP), northern Ethiopia.</p><p><strong>Methods: </strong>We collected livestock depredation data from January to July 2018 through a questionnaire survey of 300 sample households in surrounding local communities. We used descriptive and inferential statistics to analyze local communities' attitudes and perceptions toward hamadryas baboons' livestock-depredating behaviour.</p><p><strong>Results: </strong>Respondents in the study area primarily reported livestock depredation (74.6%) and drought (18.4%) as the main challenges in livestock rearing. Respondents estimated that hamadryas baboons caused damage to an average of 3.84 (± 0.36) livestock per household over five years in and around BSNP. Hamadryas baboons were reported to cause the greatest losses (average, range) to sheep (1.3, 0-5), lambs (1.1, 0-10), goat kids (0.7, 0-8), and goats (0.6, 0-4) per household over five years. Reported livestock attacks varied significantly between the wet and dry seasons. The vast majority of respondents (93.9%) reported that they did not kill hamadryas baboons in retaliation for livestock losses. Following livestock attacks, respondents primarily reported the incidents to park scouts (80.5%), doing nothing (11.8%), or attempting to scare the animals by making noise (6.0%). The intense conflict between hamadryas baboons and the local communities could seriously threaten the species' survival unless appropriate management measures are implemented.</p><p><strong>Conclusion: </strong>The results of this study provide essential information for developing management plans and implementing effective conservation strategies, and we recommend the adoption of community-based conflict mitigation approaches, including improved livestock husbandry and collaborative monitoring with park authorities, to reduce depredation and promote coexistence between local communities and hamadryas baboons.</p>","PeriodicalId":48590,"journal":{"name":"BMC Zoology","volume":"11 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13501626/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148814480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relative abundance of Osteolaemus tetraspis in Uwa, Edumanom and Ogbe-Ijaw bushmeat markets in the Niger Delta region, Nigeria.","authors":"Israel O Ogorode, Edore E Ito, Obemeata E Oriakpono, Ijeoma F Vincent-Akpu, Bolaji B Babatunde, Francis D Sikoki","doi":"10.1186/s40850-026-00281-3","DOIUrl":"10.1186/s40850-026-00281-3","url":null,"abstract":"<p><p>The dwarf crocodile Osteolaemus tetraspis is globally listed as Vulnerable, yet remains heavily harvested across West and Central Africa particularly in the Niger Delta, Nigeria. This study assessed the spatio-temporal variation in the relative abundance of O. tetraspis across three major bushmeat markets: Uwa (Edo State), Edumanon (Bayelsa State), and Ogbe-Ijaw (Delta State) to inform conservation and management interventions. Bushmeat market surveys were conducted fortnightly between October 2021 and April 2022. All crocodiles encountered were counted and measured across three size classes (60, 90, and ≥ 120 cm). A negative-binomial generalized linear mixed model (GLMM) was fitted to monthly counts of Osteolaemus tetraspis to account for overdispersion in the abundance data. Temporal (Month) and spatial (Market location) effects, as well as their interaction, were treated as fixed effects. A total of 158 O. tetraspis individuals were recorded, dominated by medium-sized (39.24%) and large-sized (39.24%) individuals. Uwa accounted for the highest proportion of individuals (60.76%), followed by Edumanon (25.32%) and Ogbe-Ijaw (13.92%). The negative-binomial GLMM model indicated significant effects of Month (χ²₆ = 19.82, p < 0.01) and Market Location (χ²₂ = 10.46, p = 0.005), as well as a significant Month × Market interaction (χ²₁₂ = 23.17, p = 0.018), demonstrating that temporal patterns in abundance differed among markets. The marginal R² value (R²ₘ = 0.48) indicated that fixed effects accounted for a substantial variation in monthly abundance. Temporal declines were pronounced in April across all markets. Trade pressure on O. tetraspis is greatest during the dry-season months of October-February, with Uwa and Edumanon emerged as the principal markets contributing to the observed trade. The dominance of medium- and large-bodied crocodiles in the trade raises concerns about depletion of reproductive adults and long-term population collapse. These findings highlight the need for market-specific regulatory strategies, dry-season harvest restrictions, enhanced monitoring in high-pressure markets, and livelihood support programs. Integrating these actions with community-based conservation are critical for sustaining remaining O. tetraspis populations in the Niger Delta.</p>","PeriodicalId":48590,"journal":{"name":"BMC Zoology","volume":"11 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13471313/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148723396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Habitat-related variation in daily activity patterns of Boutourlini's blue monkey (Cercopithecus mitis boutourlinii) in Saja Forest, Kafa Biosphere Reserve, Southwest Ethiopia.","authors":"Mulu Negesse, Tsegaye Gadisa, Tadesse Habtamu","doi":"10.1186/s40850-026-00280-4","DOIUrl":"10.1186/s40850-026-00280-4","url":null,"abstract":"<p><strong>Background: </strong>Activity budgets provide insights into how primates respond to habitat variation. Through behavioural flexibility, primates, including blue monkeys, can adjust their activity patterns and resource use under changing environmental conditions. This study compared the activity budgets of two Boutourlini's blue monkey groups inhabiting different forest zones of Saja Forest: the core and transition zones. We collected Behavioral data from August 2024 to October 2025 using the instantaneous scan sampling method.</p><p><strong>Results: </strong>A total of 19,725 behavioral observations were recorded. Feeding was the dominant activity (29.6%), while times allocated for other activities were a smaller proportion (7.5%). The core-zone group spent significantly more time on feeding (33.0%), whereas those in the transition study group spent more time on movement (29.5%), and both showed statistically significant differences. Social activity was also higher in the transition zone group (13.5%), but it was not significant. Feeding was higher in the dry season (32.11%), whereas moving was higher in the wet season (28.67%). Diurnal patterns were observed, with feeding peaking in the morning and afternoon, while resting was highest at midday. Activity budgets varied among sex-age categories, with adult females showing the highest proportion of feeding activity (33.3%).</p><p><strong>Conclusions: </strong>These findings provide baseline information on the activity budgets of two Boutourlini's blue monkey groups occupying different forest zones. The observed variation in activity budgets between study groups and across seasons suggests behavioural flexibility under different environmental conditions. Future studies involving multiple independent groups per habitat type and direct measurements of habitat characteristics are needed to better understand the ecological factors influencing behavioural variation and to support conservation planning.</p>","PeriodicalId":48590,"journal":{"name":"BMC Zoology","volume":"11 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13419307/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148622218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Leveraging biologgers to better forecast animal movement and range shifts across scales.","authors":"Alexa L Fredston, Roxanne S Beltran","doi":"10.1186/s40850-026-00276-0","DOIUrl":"10.1186/s40850-026-00276-0","url":null,"abstract":"<p><p>To predict how movement strategies shape fitness in a changing world, we must build mechanistic models of species' ranges and range shifts that align environmental data with the scales of individual perception and decision-making and jointly model biological processes from the individual to the population scale.</p>","PeriodicalId":48590,"journal":{"name":"BMC Zoology","volume":"11 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13398092/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148585552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Migration dynamics of acoustic-tagged hatchery and natural atlantic salmon smolts.","authors":"James P Hawkes, Graham S Goulette, Alejandro Molina-Moctezuma","doi":"10.1186/s40850-026-00278-y","DOIUrl":"https://doi.org/10.1186/s40850-026-00278-y","url":null,"abstract":"<p><p>We investigated the migration dynamics of two Atlantic salmon (Salmo salar) smolt origin groups (hatchery, n = 374; natural, n = 231) in the Penobscot River Estuary and Bay, Maine, U.S.A., during the springs of 2010-2012. Smolts were acoustic-tagged and tracked for approximately 100 km to evaluate differences in movement rate, migration duration, path choice, and survival. While the behavioral differences between origin groups were not consistent, differences in survival were evident. Using a Cormack-Jolly-Seber mark-recapture model, we found that rearing origin and river discharge were the primary factors influencing smolt survival. Survival decreased with increasing river discharge across the observed range. Hatchery smolts (cumulative survival: 0.40-0.69) presented higher survival rates than their natural counterparts did (0.32-0.64), a finding that is inconsistent with much of the literature on hatchery versus river-reared fish. We hypothesize that the collection method for natural smolts at a dam bypass facility, which involves novel handling and dam interaction, may have contributed to their lower survival, potentially masking any inherent advantage over hatchery smolts. These findings underscore the importance of minimizing dam-related stressors and informing management actions aimed at improving the survival of outgoing smolt cohorts.</p>","PeriodicalId":48590,"journal":{"name":"BMC Zoology","volume":"11 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149225303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Contrasting urban ecology of two hedgehog species in Central European contact zone.","authors":"Ema Cetkovská, Anita Klímová, Zuzana Pokorná, Barbora Černá Bolfíková","doi":"10.1186/s40850-026-00279-x","DOIUrl":"10.1186/s40850-026-00279-x","url":null,"abstract":"<p><strong>Background: </strong>Understanding how closely related species coexist in shared environments provides key insights into their ecological differentiation and adaptive potential. In Central Europe, the European hedgehog (Erinaceus europaeus, EE) and the Northern white-breasted hedgehog (E. roumanicus, ER) meet in an extensive contact zone that includes large urban areas. Using a seven-year dataset from the Prague Wildlife Rehabilitation Centre, we compared the two species in terms of spatial distribution, seasonal activity, and rehabilitation outcomes to assess their ecological patterns in an urban environment.</p><p><strong>Results: </strong>The species exhibited distinct spatiotemporal patterns. While the EE was mainly confined to the southwestern part of the city, the ER dominated in the east, suggesting a dispersal barrier associated with the Vltava River. The EE showed a later and narrower reproductive period, consistent with one annual litter, whereas the ER showed earlier juvenile admissions and a pattern consistent with two litters per year. The EE further showed increased late-season admissions and lower release rates, while the ER had higher rehabilitation success.</p><p><strong>Conclusions: </strong>These differences suggest an ecological asymmetry between the EE and the ER within the Prague contact zone, with the ER showing signs of greater tolerance of urban conditions and the EE appearing more constrained under local urban conditions. Our findings demonstrate that wildlife rehabilitation center data can serve as an important source of comparative ecological information and help reveal how closely related species respond to human-dominated environments when interpreted with caution.</p>","PeriodicalId":48590,"journal":{"name":"BMC Zoology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13670561/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148537374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing the 12S rRNA reference library of South African chondrichthyans to aid in eDNA metabarcoding.","authors":"Kristina Loosen, Sara Andreotti, Conrad A Matthee","doi":"10.1186/s40850-026-00272-4","DOIUrl":"10.1186/s40850-026-00272-4","url":null,"abstract":"<p><strong>Background: </strong>The rapid expansion of environmental DNA (eDNA)-based biodiversity monitoring has heightened the need for accurate and well-curated taxonomic reference databases. Although mitochondrial cytochrome oxidase I (COI) is widely used, the mitochondrial 12S ribosomal RNA gene (12S rRNA) has increasingly demonstrated strong taxonomic assignment success in chondrichthyan metabarcoding applications. The South African coastline supports one of the most diverse chondrichthyan faunas globally. However, as in many regions, coverage of 12S rRNA reference databases has remained limited. Well-represented reference libraries are critical for improving the accuracy of eDNA-based species detection. Here, we aimed to expand the regional 12S rRNA reference database for South African chondrichthyans, thereby supporting both local and global eDNA applications for widely distributed species.</p><p><strong>Results: </strong>A total of 36 chondrichthyan species, represented by 69 individuals, were sequenced to expand the 12S rRNA reference library for sharks, rays and chimaeras from South Africa's Indian and Atlantic Ocean coastlines. A newly developed primer set (V05F_898E / teleoR_Elas), designed to overlap with the commonly used Elas02 region, achieved consistent amplification across diverse lineages. The new data increased regional reference coverage from 50.3% to 69.1% and added 18 species globally. Sequence authenticity was confirmed through comparison with GenBank, and Bayesian phylogenetic analyses showed that 97.2% of sequences clustered within their expected family-level lineages, although some uncertainties remained in groups with low mitochondrial divergence or complex taxonomic histories. Percent identity analyses revealed high intraspecific similarity and clear interspecific separation across taxa. However, comparative in silico analyses of the shorter Elas02 fragment demonstrated reduced phylogenetic resolution and less consistent clustering among closely related taxa. While the Elas02 region is suitable for accurate amplicon sequence variant (ASV) matching in eDNA metabarcoding, the longer 12S rRNA fragment generated here provides improved phylogenetic resolution and may aid in the identification of unknown or ambiguous ASVs.</p><p><strong>Conclusion: </strong>The expanded 12S rRNA reference library and associated phylogenetic analyses expanded genetic resources for South African chondrichthyans and support global applications. The newly developed marker can be incorporated in future eDNA studies dealing with elasmobranchs, since it can have the added benefit of providing more phylogenetic resolution than the short Elas02 fragment.</p>","PeriodicalId":48590,"journal":{"name":"BMC Zoology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13339552/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148387888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Marine or freshwater food? The dilemma of Eurasian otter (Lutra lutra) along Bulgarian Black Sea coast.","authors":"Stanislava Peeva, Evgeniy Raichev, Dilian Georgiev, Vanesa Vassileva, Hiroshi Tsunoda, Yayoi Kaneko","doi":"10.1186/s40850-026-00275-1","DOIUrl":"10.1186/s40850-026-00275-1","url":null,"abstract":"<p><strong>Background: </strong>The Eurasian otter (Lutra lutra Linnaeus, 1758) is an endangered species in Bulgaria and is protected under national legislation. Under harsh environmental conditions, as well as the increasing anthropogenic pressure, knowledge about this species is fundamental for conservation planning. The otter occupies a broad range of freshwater habitats, and the species has also been recorded along the Bulgarian Black Sea coast. The contribution of both components of this complex habitat-freshwater and marine environments-to the otter's diet has been demonstrated.</p><p><strong>Results: </strong>The study confirmed that the otter is primarily piscivorous, consuming predominantly freshwater fish during the cold season, and - marine fish during the warm season. Non-marine arthropods were found as an essential secondary food for the otter with a relative frequency of occurrence (RFO) of 22.2%. Each of the other food categories (birds, anurans, marine-arthropods, rodents and reptiles) accounted for less than 10% RFO in the diet. Seasonality in consumption of reptiles, birds, fish, non-marine arthropods was established.</p><p><strong>Conclusions: </strong>Eurasian coastal otters used both marine and inland habitats for foraging along the Bulgarian Black Sea coast and were predominantly piscivorous overall. Among identifiable fish remains, freshwater fish occurred more frequently during the cold season, whereas marine fish were more frequent during the warm season. However, a substantial proportion of fish remains could not be assigned to either marine or freshwater origin.</p>","PeriodicalId":48590,"journal":{"name":"BMC Zoology","volume":" ","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13584275/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148340686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}