Large Mammals Research Articles

Additional Site Record of an Indian Giant Squirrel (Ratufa indica indica) with Potential Habitat Connectivity in Northern Sahyadri Western Ghats and Discussion on New Sighting Records across Maharashtra from Various News Sources

The Indian Giant Squirrel (Ratufa indica), a large arboreal rodent mammal endemic to India’s tropical forests, is experiencing population decline due to local hunting and habitat fragmentation and decline due to local hunting. During routine works in Biodiversity Park of Konkan Krishi Vidyapeeth, Dapoli in the summer month May, a sighting of R. i. indica was recorded for the first time in Dapoli, Ratnagiri district, Maharashtra, outside its previously known range. The squirrel was observed foraging and nesting in a biodiversity park surrounded by orchards and exotic plantations. Dapoli, located within the Northern Western Ghats, offers varied vegetation types and may serve as a corridor connecting known populations to new habitats. Study accumulates all the new sighting records from news reports to present the small-scale movement of species within the Maharashtra state. These records suggest a possible range expansion, potentially driven by habitat adaptability and the availability of food sources in orchards. The finding highlights the need for revisiting subspecies distribution and ensuring the conservation of emerging corridors vital for sustaining viable metapopulations of this iconic species.

Highlighting the drastic body size decline in Cantabrian Brown Bear, Chamois and Wild Horse during the Holocene

During the Holocene, Iberian ecosystems have changed dramatically in response to different biotic and abiotic drivers. Typically, the impact of these changes on ecosystems is assessed in terms of the variation of diversity in the communities that compose them. However, there are a wide variety of population-specific parameters of vital importance for the maintenance of the structure and health of these ecosystems. In this study, we have focused on the drastic decrease in body size (body mass) during the Holocene in three large mammal species in the Cantabrian Mountains. Namely, the brown bear ( Ursus arctos ), the chamois ( Rupicapra pyrenaica parva ) and the wild horse ( Equus ferus ferus ). The research combines the analysis of new findings with an exhaustive compilation of previously published data to assess changes in the body size of these species at different geographical (European, Iberian and Cantabrian Regions) and chronological scales (during the Quaternary – i.e. Pleistocene and Holocene). We aim at assessing the impact of anthropogenic and climatic factors on macromammal populations in the Iberian Peninsula, using new data obtained from the new archaeo-palaeontological site of Cueva de Llamazares (León, Spain). The results show that, although the final decline in body size during the Holocene occurred in the three species, each of them seems to have been driven by different factors. Bear populations seem more influenced by their mobility versus the potential impact of changing in human hunting dynamics, while changes in vegetation cover would have been most important for chamois, and the gradual effect of climate changes for horse populations. Research covering broad chronological ranges in the past helps understanding the present and future dynamics of these species, thus contributing to their conservation and management.

Pig models in translational surgery

Large mammals are required for surgical research since the small size of rodents does not allow the translation of the procedures to those of humans. The pig has a particularly high translational value due to its similar overall anatomy and physiology, thus used as a first choice in many fields of surgical research. In cardiovascular procedures, it contributed to stents development, coronary bypass grafting improvement and heart valve xenotransplantation. A particular focus will be done in the future to improve the models and consequently the reliability of the preclinical findings. In digestive surgery, the utility of pigs has been diverse, with the development of meshes for abdominal defects repair or improvement of surgical procedures aiming at compensate functional defects. A particular utilization has been made in liver regeneration and transplantation procedures, for which the future perspectives are wide, and in metabolic surgery research for metabolic diseases interventional therapy. In endocrine surgery, the use of the pig has mainly consisted in the development of pancreas and islets transplantation for type 1 diabetes therapy, whereas the research on the other glands is less represented. Osteoarticular and neurosurgery are fields where the use of the pig is increasing: for ethical reasons instead of non-human primate models in neurosurgery but also because the rapid growth of this species allows to test the biomechanical properties of orthopedic devices in context of skeletal growth. More generally, the pig has a particular present and future involvement for testing new surgical equipment or bioengineering solutions, developing new minimally invasive approaches and robotic surgery training, regardless of the field. Finally, pig-to-human organ xenotransplantation represents a major translational surgery challenge. If the research has reached a milestone with some living patients grafted with heart or kidney from pigs with multiple genetic modifications, additional findings are required to demonstrate the safety and the long-term benefit and to extend it to other organs like the liver. In summary, the pig model has led to many advances in surgical research, with future prospects focusing primarily on xenotransplantation. However, the use of the pig in biomedical research will have to deal with growing societal ethical expectations.

Relationship Between Rotational Device Kinematics and Head Kinematics in a Large Animal Model of Traumatic Brain Injury.

Large mammal head injury models allow the pathophysiological response associated with traumatic brain injury (TBI) to be studied in vivo with precise control of the physical parameters. However, only some studies have used skull-mounted sensors to measure the kinematics of the animal head rather than relying on measurements of the system delivering the impact. Therefore, the aim of the current study was to compare the kinematics between a rotational injury device (HYGE, Inc., Kittanning, PA) and the head in a swine model of TBI across a range of target peak angular velocities. Sexually mature Yucatan swine were subjected to a rotational TBI via the HYGE device at one of three targeted peak angular velocities: 110rad/s (n = 16), 145rad/s (n = 12) or 170rad/s (n = 11). Sensor packages were used to measure both the angular kinematics of the animal head and HYGE deviceswing arm. Peak angular velocity of the animal head was on average 18-33% lower compared to that of the HYGE device swing arm with greater relative differences for greater target peak angular velocities. Similarly, peak angular acceleration of the animal head was lower than that of the HYGE device sing arm by 11-34% on average with greater relative differences for greater target peak angular velocities. This study highlights the importance of directly measuring the head kinematics of the animal in TBI models for the purpose of directional comparisons, finite element simulations, and/or scaling kinematics from human-to-animal to determine boundary conditions or animal-to-human to develop injury criteria.

Exposure to PFOS, PFBS, PFOA and PFBA impairs cell cycle progression in bovine brain (Bos taurus) endothelial cells.

Exposure to PFOS, PFBS, PFOA and PFBA impairs cell cycle progression in bovine brain (Bos taurus) endothelial cells.

Canine prostate cancer cell transcriptome reveals important dysregulation in PI3K/AKT/mTOR pathway.

Canine prostate cancer cell transcriptome reveals important dysregulation in PI3K/AKT/mTOR pathway.

Reproductive seasonality influences follicle dynamics and the ovarian extracellular matrix structural properties in ewes.

Ovarian function requires dynamic tissue remodeling provided by its extracellular matrix (ECM). In seasonal breeders, ovaries undergo an additional circannual cycle of recrudescence and regression. Whilst increasing evidence suggests that the ECM impacts normal ovarian cyclicity and function, how its components are remodeled across reproductive seasonality has not been explored in large mammals. Using immunohistological and in vitro experiments, we investigated the influence of reproductive seasonality on ovarian morphometry, ECM properties, and follicle developmental potential in vitro. Ovarian weight and volume were reduced during anestrus (P < 0.001). Neither follicular density nor the proportion of preantral follicles and earlier stage of development were impacted by the season, but the percentage of antral follicles increased during anestrus (P = 0.028) while corpora lutea were only present in ovaries collected during the breeding season. Concomitantly, ovarian ECM composition was significantly remodeled, with stromal collagen and fibronectin significantly increased (P < 0.01) and laminin decreased (P = 0.032) during anestrus compared to the breeding season. This correlated with thicker collagen fibers both in the stroma and in the tunica albuginea at anestrus. In vitro, preantral follicles isolated from their native environment exhibited a season-dependent pattern of follicular integrity, survival, antrum formation and growth. These results suggest the establishment of a stiffer ovarian microenvironment during anestrus, which, together with endocrine changes, regulate follicle growth, demise and the ovulatory response.

Marked regionalism during the Last Glacial across the Italian Peninsula: Evidence from the large mammal assemblage of Santa Maria di Agnano (Apulia, southern Italy)

Marked regionalism during the Last Glacial across the Italian Peninsula: Evidence from the large mammal assemblage of Santa Maria di Agnano (Apulia, southern Italy)

Genomes of critically endangered saola are shaped by population structure and purging.

Genomes of critically endangered saola are shaped by population structure and purging.

Effects of human disturbance on medium and large mammals in primary and secondary tropical forests in Southern Mexico

Introduction: In tropical forests, populations of medium and large mammals are being impacted by human activities. Understanding how species respond to land use conversion, fragmentation, and the encroachment of roads density and settlements is of conservation interest in highly biodiverse regions. Objetive: To assess the effect of human disturbance and environmental variables on trophic guilds of medium and large mammals in the tropical forests of the Sierra Negra-Mazateca in Southern Mexico. Methods: We characterized the landscape (land use and vegetation, number of fragments, and edge density) through supervised classification of Landsat 8 images. We recorded species using camera-trap stations and evaluated the relationship between the presence and relative abundance of species with human disturbance variables using zero-inflated regression models. Results: The landscape of the Sierra Negra-Mazateca is dominated by fragments of secondary forests (48.6 %) with a small proportion of primary forests (9.6 %). We found no differences in the overall relative abundance of species between primary and secondary forests, but differences were observed for omnivore and carnivore guilds. Human disturbances had a disparate effect among guilds, negatively affecting carnivores and positively herbivores. Conclusions: Secondary forests are refuges for tolerant species. Nevertheless, we emphasize the need to conserve primary forests to safeguard medium and large mammals, especially the carnivore guild. Extensive management in secondary forests is recommended to conserve remaining primary forests, alongside community awareness and empowerment for coexistence with wildlife.

The scaled sardine’s unique metabolic phenotype and its implications for the susceptibility of small tropical pelagic fishes to climate change

Small pelagic fishes (e.g., sardines, anchovies and their relatives) are preyed upon by large predatory fishes, birds and mammals, and thus, are key species in marine food webs and with respect to ecosystem health and productivity. However, we know little about their physiology, and such information will be critical to predicting how their populations may be impacted by human-induced rapid environmental change (HIREC) and in implementing effective conservation strategies. As a first step, we determined the maximum swimming speed, aerobic capacity [maximum metabolic rate (MMR) and aerobic scope (AS)] and cost of transport (COT; the energy required to swim a given distance) of scaled sardines (Harengula jaguana) collected in Eleuthera (The Bahamas). The scaled sardine’s critical swimming speed (Ucrit) was ~ 5–6 body length’s per second, and this agrees with data collected on free-swimming schools of similar fishes in the wild. However, they had unexpectedly high values for MMR and AS (~ 25% and 70% greater than tuna, respectively), and for COT. These findings have important implications with regard to how these ecologically important fishes will potentially respond to HIREC-related challenges such as increased temperature and decreases in the biomass and size of plankton upon which they feed.

Perception Toward Wolves Are Driven by Economic Status and Religion Across Their Distribution Range.

Effective conservation of large mammals depends on how people perceive them. Grey wolves have a widespread distribution globally, and their recent recolonization of human-dominated landscapes offers an excellent opportunity to understand the heterogeneity in their perception across continents. Our analysis included all quantitative studies (118 articles) conducted in 35 countries through a systematic review process, published globally between 1980-2023 and indexed in Web of Science and Google Scholar. Fifty-four percent of the studies reported a negative perception toward wolves. Most studies conducted in Asia reported a negative perception, while 56% of studies conducted in Europe and 48% in North America reported a positive perception. Fifty-four percent of studies from Western Europe and forty percent of studies from Slavic Russian cultural regions reported positive perceptions. Respondents from low-income countries elicited the most negative perceptions. We identified the predominant religion and economic status of a country as dominant factors determining perception. Studies conducted in countries with Hinduism as the predominant religion reported a negative perception toward wolves. We recommend that future studies on human-wolf interactions must prioritize regions within central Europe, parts of Asia, and Russia. A global human-wolf coexistence strategy should consider the social factors driving attitude toward the species.

Abstract 6715: Cross-species investigation of gene copy number and cancer resistance

Low cancer incidence rates are observed in large mammals such as elephants and whales, despite their mass and long lifespan hypothetically contributing to a higher lifetime probability of acquiring oncogenic mutations. Few studies have investigated cancer-related genes in these animals. One reported that bowhead whales possess two functional copies of PCNA. Multiple studies have investigated the presence of multiple retrogene copies of TP53 in elephants. Extra copies of genes involved in DNA damage detection and repair could contribute to cancer resistance. Droplet digital PCR (ddPCR) was used to quantify gene copy number for TP53, PCNA, HER2, DLG1, and DLG2 in genomic DNA extracted from frozen skin samples of beluga, narwhal and bowhead whales (n=20 each). Results showed that all 3 whale species had more than one copy of PCNA. Agarose gel PCR showed the simultaneous presence of wild-type PCNA (possessing introns) and variable numbers of pseudogene sequences (lacking introns) within individuals for belugas, narwhals, and bowheads. ddPCR found that elephants did not have increased PCNA copy number, but agarose gel PCR showed the presence of PCNA pseudogenes. Similar patterns were also observed in rhinos, horses, cows and other ungulate species. To investigate copy number loss in cancer, ddPCR was performed on formalin-fixed, paraffin embedded normal and matched tumor tissue of 7 individual belugas from the St. Lawrence estuary, an area that was historically contaminated with industrial carcinogens. Copy number loss was not observed for any investigated tumor suppressor gene in tumor tissue compared to normal tissue. Our results show that bowhead whales are not unique in having multiple copies of PCNA. The presence of incomplete copies with unknown function may influence copy number quantification. Further study is required to understand the significance of the variable PCNA pseudogene copies. Understanding natural copy number variation in tumor suppressor genes may provide insight into risk factors and prevention methods across species. Citation Format: Morla Phan, Thompson Worden, Sarah Adamowicz, Stéphane Lair, Mauricio Seguel, Claire Jardine, Geoffrey Wood, Dirk Steinke. Cross-species investigation of gene copy number and cancer resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6715.

Unraveling the relationships between midge abundance and incidence, microbial communities, and soil and water properties in a protected natural tallgrass prairie

BackgroundBiting midges (Culicoides spp.) are small blood-feeding flies (Diptera: Ceratopogonidae) that transmit numerous pathogens that impact animal and human health. The larvae of several Culicoides spp., including vectors, are often found in organically enriched, moist soil habitats. However, the influence of biotic (e.g., cohabiting fauna, potential prey taxa) and abiotic factors (e.g., soil or water properties, time) on abundance and incidence of larval Culicoides in natural habitats is not well understood. This study evaluated the relationships between bacterial and protistan communities, soil and water physicochemical properties, and the abundance and incidence of Culicoides species in larval habitats at the Konza Prairie Biological Station in Kansas.MethodsSoil and water samples were collected monthly from March 2021 to February 2022 from four midge larval habitat sites, including three grazed (low-production cattle-grazed (LPCG), high-production cattle-grazed (HPCG), and bison-grazed sites) and one formally ungrazed (i.e., no managed large mammals) site. Midge incidence and abundance were evaluated using emergence assays, which assessed the number of adults emerging from collected soil samples, and bacterial and protistan communities in these samples were characterized through amplicon sequencing of the 16S and 18S rRNA genes. Physicochemical properties of water and soil were also analyzed.ResultsIrrespective of site, the highest midge abundance was reported in warmer months between March and September, except June. Moreover, the greatest midge abundance, incidence, and prevalence occurred at the HPCG and bison-grazed sites, which had a persistent water source. Specific lineages of bacterial and protistan communities, soil texture, organic matter, and total dissolved solids in water samples were directly associated with the abundance of Culicoides spp. that emerged from soil samples.ConclusionsBoth biotic (bacterial and protistan communities, presence of host animals), and abiotic (soil and water properties, season) factors affected the abundance and incidence of Culicoides spp. in natural habitats. The results presented in this study expand our understanding of the ecological and environmental factors influencing larval ecology of biting midges in natural developmental substrates. These insights have important implications for identifying potential developmental sites, which can be used for targeted management of Culicoides.Graphical

Splenic Modulation of the Early Inflammatory Response to Regional and Global Ischemia/Reperfusion Injury in Swine.

Background: The spleen has been identified as a source of pro-inflammatory leukocytes mobilized after local ischemic injury in rodents. However, the role of the spleen in the inflammatory response to regional or global ischemia/reperfusion injury (IRI) in larger mammals is unknown. We investigated the spleen's contribution to early IRI-associated inflammation in porcine models of acute reperfused myocardial infarction (AMI) and sudden cardiac arrest (SCA). Methods: Swine were randomized to splenectomy (SPLX; n=15) or sham surgery (SHAM; n=15) 1-week before a 75-minute coronary occlusion (AMI; n=6/group) or 8-minutes of ventricular fibrillation and CPR (SCA; n=9/group). Hemodynamic assessment and echocardiography were performed before and after IRI, with serial blood sampling to assess leukocyte mobilization and cytokine release. Heart and brain samples were collected for post-mortem evaluation of injury and leukocyte infiltration. Results: Early post-IRI leukocyte mobilization, cytokine levels, and leukocyte infiltration were similar between groups in each protocol. After SCA, SHAM animals showed a significant 41±5% increase in hematocrit and 30±4% rise in arterial O2-content during CPR that was absent after SPLX. These differences persisted for up to 90-minutes and were associated with prolonged time to return of spontaneous circulation (ROSC) and increased vasopressor support in the SPLX group. Conclusions: Contrary to findings in rodents, the spleen is not required for the early inflammatory response to regional or global IRI in swine. However, splenic erythrocyte mobilization during SCA leads to an increase in arterial O2-content that is associated with earlier ROSC and reduced reliance on vasopressors during CPR and the post-resuscitation period.

Sodium Retention in Large Herbivores: Physiological Insights and Zoogeochemical Consequences.

The assimilation, retention, and release of nutrients by animals fundamentally shapes their physiology and contributions to ecological processes (e.g., zoogeochemistry). Yet, information on the transit of nutrients through the bodies of large mammals remains scarce. Here, we examined how sodium (Na), a key element for animal health and ecosystem functioning, travels differently through fecal and urinary systems of cows (Bos taurus) and horses (Equus ferus caballus). We provided a large dose of Na and compared its timing of release in feces and urine to that of nonabsorbable markers. Na excretion by urine occurred approximately twice as fast as excretion by feces, yet both were shorter than indigestible particle markers. These differences correspond to rapid absorption of Na in the upper gastrointestinal tract and transport by blood to the kidneys (urine Na excretion) or resecretion of Na into the lower intestinal tract (fecal Na excretion). Interestingly, for cows, we found a second peak of Na excretion in urine and feces > 96 h after dosage. This result may indicate that surplus Na can be rapidly absorbed and stored in specific body cells (e.g., skin), from which it is later released. Using a propagule dispersal model, we found that the distance of cattle- and horse-driven nutrient dispersal by urine was 31% and 36% less than the fecal pathway and 60% and 41% less than the particle marker pathway, which is commonly used to estimate nutrient dispersal. Future physiological and zoogeochemical studies should resolve different pathways of nutrient retention and release from large mammals.

The range of large terrestrial mammals has expanded into human-dominated landscapes in Japan

Large terrestrial mammals have generally declined due to human activity, but the recovery of some populations poses new issues for coexistence. Few studies to date have investigated drivers of this recovery and its impacts on human societies at the national scale. Here we assessed the range expansion of six large terrestrial mammal species over 40 years—sika deer, wild boar, Japanese serow, Japanese macaque, Asiatic black bear, and brown bear—by comparing newly occupied and unoccupied areas using distribution data in Japan. We found evidence that increased agricultural abandonment and decreased snowfall drove these range expansions. The range of all six species expanded from mountainous landscapes to those closer to human settlements, leading to increased conflicts that threaten people’s property and safety. We predict that accelerating depopulation and climate warming could further expand the range of these species, and call for measures to mitigate conflicts and achieve coexistence with them.

Climate change impacts on altitudinal movements of society large mammals in the Alborz

This study examines the impact of climate change on the altitudinal movement patterns and number of individuals of four large mammal species within the Central Alborz Protected Area (CAPA) region of the Alborz Mountains, a biodiversity hotspot, over a 23-year period (1999 to 2022). During the warm season (May 25–September 29), temperatures were reported to have increased by 2–2.5 °C, while relative humidity was observed to have decreased by 4–4.5%. Compared to the past two decades (2000–2022), Caspian red deer were observed to initiate their annual high-altitude migrations 15–20 days earlier, with the number of individuals in the summer range increasing more than threefold. Wild goats also migrated earlier, with peak arrivals increasing from 20–36 (1999–2003) to 36–57 (2018–2022) between May 25 and May 31, highlighting temperature as the primary driver of herbivore movement. In contrast, brown bears exhibited more subtle altitudinal movement, likely influenced by both temperature and humidity. Wild boars, with an approximate 40% increase in the number of individuals, tended to return to lower elevations earlier than in previous years (1999–2003). These patterns highlight the role of climate as a significant regulator of movement ecology, influencing high-altitude habitat use. However, human-induced barriers, such as roads and settlements, present additional threats to these seasonal migrations. This underscores the urgent need for adaptive management strategies, including the protection of movement corridors, the expansion of core zones, and enhanced community engagement, to support the resilience of these species under changing climatic conditions.

The cave hyena den of Grotta Guattari (San Felice Circeo, central Italy): first faunal and environmental data from the MIS 4 deposit

Grotta Guattari (San Felice Circeo, central Italy) is a key site of Italian and European prehistory. The cave was a Late Pleistocene hyena den that became famous in 1939 following the discovery of one of the best-preserved Neanderthal skulls in the World. New archaeological investigations were carried out between 2019 and 2023 in a peripheral chamber previously unexcavated, known as the Antro del Laghetto. Thousands of bone remains, tens of coprolites and a small lithic collection were recovered from a deposit dating to 66-65 ka. This paper presents the archaeological investigations conducted and the recently uncovered large mammal assemblage. Taxonomic and taphonomic analyses allowed us to identify at least 25 different taxa, some of which had never before been recorded at this site, and which were hunted or scavenged and transported by cave hyenas. However, for the first time at Grotta Guattari, cut marks were identified on two bones, prompting further investigation into the possible human role at the site. On this topic, the discovery of several fragmented Neanderthal bones displaying evidence of gnawing is particularly noteworthy. The palaeoecology of the identified taxa provides an opportunity to propose an environmental reconstruction of the area at the end of MIS 4. This study highlights that this coastal region was characterised by different habitats, within which several faunal and floral species survived minor climate oscillations, probably due to the climate mitigation provided by the Tyrrhenian Sea.

A multi-species corridor between the Andean Amazonian and Amazon floodplain landscapes: prioritizing ecological connectivity areas for jaguar and threatened ungulates in the north-eastern of South America

The spatial heterogeneity and variability of environmental conditions in the Colombian Amazon, located in north-western South America, are key factors explaining the high diversity of mammal species, representing 49% of those reported for Colombia. In recent decades, the Amazon forest system has experienced accelerated transformation due to deforestation, forest fires, extensive cattle ranching, and road infrastructure development, leading to degraded natural habitats and reduced connectivity among populations of large mammals in areas ecologically important for these species. However, there has been a lack of structural connectivity analysis in the Andean Amazonian and Amazon floodplain landscapes using a multi-species approach that considers predator–prey relationships among representative groups such as large felids and wild ungulate species. To address this gap, we utilized occurrence data for focal species including the jaguar, lowland tapir, and collared peccary. We developed potential distribution models, conducted binarization processes, analyzed spatial morphological patterns, and constructed a resistance matrix. This information was used to model dispersal corridors and identify nodes connecting core habitats of the focal species using the randomized shortest path algorithm, along with quantifying weighted global connectivity metrics. Our findings indicate the presence of an integrated corridor comprising potential low-cost dispersal routes for the focal species, primarily associated with the hydric network of the upper and middle Caquetá River basin. These corridors connect key protected areas such as Alto Fragua Indi Wasi, La Paya, and Serranía del Chiribiquete National Natural Parks, as well as the Cerro Páramo de Miraflores Rigoberto Urriago, Miraflores, and Picachos Regional Parks.