Tiger Research Articles

Gut Microbiome Diversity and Composition in Captive Siberian Tigers (Panthera tigris altaica): The Influence of Diet, Health Status, and Captivity on Microbial Communities

The gut microbiome is essential for the health of carnivorous mammals, including the endangered Siberian tiger (Panthera tigris altaica). However, limited research exists on the gut microbiome of captive Siberian tigers, especially regarding how diet and health status influence microbial diversity. This study addresses this gap by investigating the gut microbiome diversity and composition of six captive-born Siberian tigers housed at the Baekdudaegan National Arboretum in South Korea, using 16S rRNA gene sequencing. The study aimed to examine how diet and health status influence microbial communities, providing baseline data for managing captive tigers. Alpha diversity analysis revealed significant variation in microbial richness and evenness, with Tigers 2 and 6 exhibiting the highest microbial diversity and Tiger 3 the lowest, likely due to its surgical history and limited diet. Beta diversity analysis showed distinct microbial community structures influenced by diet and health. Taxonomic profiling identified Firmicutes and Bacteroidota as the dominant phyla, with Clostridium sensu stricto more prevalent in healthier tigers, while Escherichia-Shigella and Proteobacteria were abundant in tigers with lower diversity, suggesting dysbiosis. Comparisons with other tiger species confirm that diet, health, and captivity significantly shape the gut microbiome. These findings highlight the need for personalized health management in captive environments.

SARS-CoV-2 within-host population expansion, diversification and adaptation in zoo tigers, lions and hyenas.

SARS-CoV-2 rapidly adapts to new hosts following cross-species transmission; this is highly relevant as novel within-host variants have emerged following infection of susceptible wild and domestic animal species. Furthermore, SARS-CoV-2 transmission from animals (e.g., white-tailed deer, mink, domestic cats, and others) back to humans has also been observed, documenting the potential of novel animal-derived variants to infect humans. We investigated SARS-CoV-2 evolution and host-specific adaptation during an outbreak in Amur tigers (Panthera tigris altaica), African lions (Panthera leo), and spotted hyenas (Crocuta crocuta) at Denver Zoo in late 2021. SARS-CoV-2 genomes from longitudinal samples collected from 16 individuals were evaluated for within-host variation and genomic signatures of selection. The outbreak was likely initiated by a single spillover of a rare Delta sublineage subsequently transmitted from tigers to lions to hyenas. Within-host virus populations rapidly expanded and diversified. We detected signatures of purifying and positive selection, including strong positive selection in hyenas and in the nucleocapsid (N) gene in all animals. Four candidate species-specific adaptive mutations were identified: N A254V in lions and hyenas, and ORF1a E1724D, spike T274I, and N P326L in hyenas. These results reveal accelerated SARS-CoV-2 adaptation following host shifts in three non-domestic species in daily contact with humans.

Intact, under-patrolled forests harbor widespread prey but a male-biased tiger population in the Ulu Masen Ecosystem, Sumatra, Indonesia

Conservation of threatened species is dependent on consistent population monitoring. We present the first status assessment of critically endangered Sumatran tigers (Panthera tigris sumatrae) and their prey in the Ulu Masen Ecosystem, Aceh, Indonesia. Our estimates of tiger habitat use are the first reported for a Sumatran ecosystem unprotected at the national level. During 6,732 trap nights accumulated over 23 months of camera-trap monitoring in 2020 and 2022, tigers were detected 39 times at 16 of the 52 stations. We identified 11 individual tigers but sex ratios were highly skewed: 8 males, 1 female, and 2 individuals of unknown sex. Cubs were not photographed either year and we did not observe evidence of tiger reproduction. Tiger habitat use (Ѱ = 0.52, SE = 0.15) was negatively influenced by human disturbance and positively influenced by elevation but those associations were not significant. Our study documents a widespread prey base but uncovers demographic characteristics of tigers indicative of heavy poaching pressures. We conclude that tiger-targeted protection is urgently needed to ensure the species’ persistence in Ulu Masen which, together with the adjacent Leuser Ecosystem, represents the largest contiguous tiger conservation landscape remaining in Sumatra.

Protection beyond park boundaries: On the impact of systematic patrolling in Divisional Forest Office, Sarpang, Bhutan

AbstractProtected areas and biological corridors play a crucial role in conserving biodiversity and promoting connectivity between habitat patches. Bhutan, known as a stronghold for tigers (Panthera tigris), has dedicated a significant portion of its land to a network of protected areas and biological corridors. However, these areas face risks from illegal activities, posing challenges for their management. To address this, the Department of Forests & Park Services in Bhutan deployed an adaptive management framework, informed by the Spatial Monitoring and Reporting Tool in 2016 in the Divisional Forest Office, Sarpang, an important corridor area outside of official protected area boundaries. This study analyses 5 years of data (2017–2021) recorded through a monitoring tool to assess changes in ranger activities and on‐ground observations. The results show improved data availability, increased patrol effort, enhanced monitoring of wildlife, and a reduction in threat detection over time. Furthermore, camera trap surveys targeting tigers reveal a potential increase in the number of individual tigers utilizing the corridor since the adoption of the tool and other management actions. These findings highlight the effectiveness of these efforts in a critical wildlife corridor.

Tiger shikars: The Wodeyars’ construction of a Rajput identity through sport

Abstract This article explores the practice of the sport of tiger hunting among the Wodeyars, the maharajas of Mysore, through an examination of art, archival records, state gazetteers, and a tour diary of Krishnaraja Wodeyar IV. It argues that the Wodeyars only adopted the sport as an expression of kingship in the late nineteenth century, under British influence. This, I posit, was part of their larger attempt to align their kingship to more popular Indian modes, specifically the Rajputs. By reading accounts of the sport in Krishnaraja Wodeyar’s tour diary, along with examining the Wodeyars’ attempts at forging kinship relations with the Rajputs, the article demonstrates how the sport became crucial to the Wodeyars’ assertion of a Rajput identity and to attempts to obtain a higher position in the princely hierarchy of the colonial period. The recognition that the success of tiger hunts was significant to Rajput kingship and identity, along with rising concern over the diminishing tiger population, led the Wodeyars to enclose forests, establish private hunting preserves and a shikar department, and classify tiger as game in an attempt to improve the sport and make it exclusive.

Recent enrichment of megafauna in the north of Eurasia supports the concept of Pleistocene rewilding

‘Pleistocene rewilding' refers to the concept of restoring ecosystems to their state during the Pleistocene epoch, by (re‐)introducing species or their close relatives that were present during that time, in an effort to revive ecological processes that existed before human‐driven extinctions. This concept is highly controversial for both ethical and ecological reasons. Here I review evidence of recent northward range expansions of various large land mammals in boreal Eurasia, and discuss whether this provides evidence that rewilding projects might be justified and feasible. Around 100 years ago, the native boreal fauna of Eurasia included five species of large land mammals: moose Alces alces, brown bear Ursus arctos, wolf Canis lupus, reindeer Rangifer tarandus, and snow sheep Ovis nivicola, but since then the list has expanded. This is due to the introduction of bison Bison bonasus, Bison bison, muskox Ovibos moschatus, non‐native deer, and feral horses, as well as the northward expansion of wild boar Sus scrofa, roe deer Capreolus capreolus, Capreolus pygargus, and red deer Cervus canadensis. In addition, several southern species temporarily occurred in the north, including tiger Panthera tigris, sika deer Cervus nippon, and yak Bos grunniens. This ongoing enrichment of the boreal fauna is reminiscent to Pleistocene rewilding. However, so far, the abundance of expanding large mammals species remains low. Large‐scale projects on Pleistocene rewilding are labor‐intensive, expensive, and not popular enough to receive support, and therefore their realization is problematic

Dimensions of human–tiger conflict and solutions for coexistence in the forests of the Khata Corridor, Bardiya, Nepal

Abstract Khata Corridor forest, which serves as a border crossing for wildlife between Nepal and India, is one of the areas in Nepal with the highest incidence of human–wildlife conflict. In recent years both the tiger Panthera tigris tigris and human populations in this region have increased, leading to more frequent conflict. We aimed to determine whether increased conflict risk was primarily from tigers entering human settlements or whether there are additional drivers associated with human use of forested areas. We conducted the study in four settlements that varied in socio-economic status and distance from Bardiya National Park, through field visits and household surveys. Tiger records (sightings, pug marks and attacks) were most frequent far from Bardiya National Park, in settlements without benefits from tiger-based tourism and nearer the periphery of forest, and were rarely associated with the interior of settlements. Human visitation into forests was also highest in the most remote settlement. Our findings suggest that conflict risk is driven by the extent of human activity in forested areas, reflecting an unequal distribution of the conservation benefits of tourism amongst settlements. In the long-term, continued coexistence between people and tigers will depend on minimizing conflict risk across settlements through establishing an equitable distribution of conservation benefits. In the short term, we recommend raising public awareness of tiger behaviour to emphasize that tigers are highly unlikely to enter and occupy the interior of human settlements, mitigating negative perceptions of conflict risk.

Did Panthera gombaszogensis reach the Sunda shelf?

ABSTRACT The history of Panthera throughout Asia is dependent on a very scant fossil record. Dominating Asia in the Holocene, Pleistocene Panthera fossils have often been attributed to Panthera tigris. However, newer finds suggest that there was more than just P. tigris in Pleistocene Asia. Rather, species previously thought to be only from western Eurasia have been uncovered in South and East Asia, including Panthera spelaea and Panthera gombaszogensis. Therefore, re-evaluation of the fossil Panthera from Pleistocene Sunda is indicated. A partial mandible from Kedung Brubus (MIS 20–15) shows characteristics distinct from both contemporary Pleistocene P. tigris and Holocene Sunda populations. Rather, this specimen shows strong affinities with the Eurasian P. gombaszogensis. The Kedung Brubus mandible therefore provides the first evidence for the presence of P. gombaszogensis in Middle Pleistocene Sunda, becoming extinct some time after the arrival of P. tigris.

Human-Wildlife Conflict in Bardia-Banke Complex: Patterns of Human Fatalities and Injuries Caused by Large Mammals.

Human fatalities and injury from wildlife attacks often result in a negative attitude toward conservation. This research was undertaken to investigate the patterns and conflict-causing factors of human killing and injury by large mammals, especially by Asian elephant (Elephas maximus), common leopard (Panthera pardus), and Bengal tiger (Panthera tigris tigris) in the Bardia-Banke Complex of western Nepal. We collected human death and injury records caused by wildlife in the Bardia-Banke Complex between 2019 and 2023, based on relief applications submitted by the victim's family. Additionally, camera trap monitoring was conducted following incidents of human-tiger and human-leopard conflicts. A total of 76 incidents involving human casualties and injuries were considered for analysis. Incidents of livestock depredation, crop raiding, and property damage were excluded from the analysis. Most of the attacks on humans were caused by tigers (75%), followed by elephants (16%) and leopards (9%). Almost all incidents occurred in daytime (97%). The highest number of conflicts were recorded in 2021, with 20 incidents. Most of the cases (84%) occurred within 1 km of forest edge. Khata corridor and the western side of the Bardia National Park, i.e., Karnali River corridor, were identified as high-conflict areas. The primary causes of the conflict manifested in cattle grazing (28%), grass cutting (28%), firewood collection (11%), fishing (8%), vegetable collection (5%), sand collection (4%), during rescuing friends (3%), grazing captive elephants (3%), highway rides (3%), sleeping in Chaupadi Goth (3%), walking nearby forest areas (3%), playing nearby forest areas (1%), while feeding pig (1%), and working in agricultural lands (1%). To promote human-wildlife coexistence, community-based patrols (33%), habitat restoration (26%), electric fencing (26%), and insurance (7%) were identified as the preferred strategies. Therefore, we recommend that stakeholders and concerned bodies increase awareness among local community about the use of forest resources, wildlife behavior, and human-wildlife conflict mitigation strategies.

External and internal driving forces of community and functional group stability in the forest mammal community

Conserving mammal community stability in forest ecosystems is an urgent challenge in the face of global biodiversity threats and complex trophic interaction. However, understanding of the stability of mammal communities and targeted functional groups is still limited, hindering adaptive strategy development. We collected 210 120 camera trap photos across 5897 km 2 within the Amur tiger ( Panthera tigris altaica ) range in China’s natural forests. We decomposed stability into compensatory effects, statistical-averaging effects and population stability. Using structural equation modelling, we explored the impact of external factors, species diversity and vertical effects on the stability of the community and of four functional groups. As external factors, primary productivity increased the stability of top predators, while precipitation had inconsistent effects. Horizontal diversity (richness and evenness) positively impacted community stability. However, the vertical structure of the community, including trophic-level richness and functional groups’ compensatory dynamics, were the largest drivers for maintaining community stability. Horizontal diversity within functional groups and the diversity or biomass of their food resources/consumers both influenced the stability of functional groups. Our results recognize the importance of conserving and even re-establishing vertical trophic structures in forest communities. Acknowledging multiple levels of stability, from functional groups to communities, is an indispensable step for effective conservation strategies.

Графовые алгоритмы для расчёта распределения следов амурского тигра на территории Приморского края

The paper analyzes the distribution of the Amur tiger (Panthera tigris altaica) tracks in the Primorsky Krai municipalities according to observations obtained during the one-time winter count organized by the Pacific Institute of Geography of the Far Eastern Branch of the Russian Academy of Sciences in 2005. This task is related to the need to calculate the number of animals based on the tracks of their vital activity. Based on the initial data we form a sample to analyze a set of tracks to identify intersection areas of various tiger habitats in Primorsky Krai. The map of Primorsky Krai municipalities was presented in the form of a planar graph to identify their intersections. A recurrent algorithm for identifying tiger clusters was developed using graph theory methods. According to them, the territory of Primorsky Krai is divided into northern, central, southern and southwestern zones with intersections. The districts of Primorsky Krai included in the designated zones are listed. The total number of tracks in intersecting adjacent zones was counted to identify possible tiger migrations in Primorsky Krai. A quantitative assessment of the degree of intersection of the selected zones by the number of tiger tracks is given. The proposed calculation scheme can be used to clarify and verify the results of modeling the spatial distribution and total population size of the Amur tiger.

Gut microbiota dynamics of adult and sub‐adult sika deer during reintroduction

AbstractPrey populations significantly influence the distribution of top predators. The sika deer (Cervus nippon), a key prey species for the Amur tiger in Northeast China, plays a critical role in the recovery and dispersal of Amur tiger populations. Reintroduction is a pivotal strategy for restoring prey populations, but it presents challenges, especially in terms of adaptation to the natural environment during the natural training process before animals are released. In this study, we sampled six adult and six sub‐adult sika deer and employed high‐throughput sequencing of the 16S ribosomal RNA gene to investigate changes in gut microbial diversity, composition, and function during natural training. The results showed that adult sika deer had higher gut microbiota diversity compared to sub‐adults. However, as natural training progressed, the gut microbial diversity in sub‐adults approached that of adults. Additionally, beneficial, fiber‐digesting bacteria associated with adaptation to the natural environment tended to increase during nature training in both adult and sub‐adult sika deer, while pathogenic bacteria tended to decrease. We also compared the metabolic function of the gut microbiota in adult and sub‐adult sika deer, which showed that the carbohydrate metabolic function of both adults and sub‐adults decreased significantly with natural training, declining more rapidly in sub‐adults. Conversely, the lipid metabolic function in sub‐adults increased significantly with natural training. Overall, a period of nature training is necessary before reintroducing animals to their natural habitats, and sub‐adult sika deer, in particular, exhibit greater adaptability to environmental changes as reflected by their gut microbiota dynamics. These findings offer valuable insights for the reintroduction of sika deer and other ungulates. We recommend incorporating natural training in reintroduction programs and prioritizing sub‐adult animals for reintroduction.

Unraveling the genomic diversity and admixture history of captive tigers in the United States

Genomic studies of endangered species have primarily focused on describing diversity patterns and resolving phylogenetic relationships, with the overarching goal of informing conservation efforts. However, few studies have investigated genomic diversity housed in captive populations. For tigers (Panthera tigris), captive individuals vastly outnumber those in the wild, but their diversity remains largely unexplored. Privately owned captive tiger populations have remained an enigma in the conservation community, with some believing that these individuals are severely inbred, while others believe they may be a source of now-extinct diversity. Here, we present a large-scale genetic study of the private (non-zoo) captive tiger population in the United States, also known as "Generic" tigers. We find that the Generic tiger population has an admixture fingerprint comprising all six extant wild tiger subspecies. Of the 138 Generic individuals sequenced for the purpose of this study, no individual had ancestry from only one subspecies. We show that the Generic tiger population has a comparable amount of genetic diversity relative to most wild subspecies, few private variants, and fewer deleterious mutations. We observe inbreeding coefficients similar to wild populations, although there are some individuals within both the Generic and wild populations that are substantially inbred. Additionally, we develop a reference panel for tigers that can be used with imputation to accurately distinguish individuals and assign ancestry with ultralow coverage (0.25×) data. By providing a cost-effective alternative to whole-genome sequencing (WGS), the reference panel provides a resource to assist in tiger conservation efforts for both ex- and in situ populations.

TigerBase: A DNA registration system to enhance enforcement and compliance testing of captive tiger facilities

The illegal trade in tigers (Panthera tigris) and their derivatives, such as bones, teeth and pelts, is a major threat to the species’ long-term persistence. As wild tiger populations have dwindled, a large proportion of trafficked tiger products now derive from captive breeding facilities found throughout Asia. Moreover, wild tigers have been poached and laundered into captive facilities, then falsely designated as captive-bred. The establishment of a DNA registration system is recognized as a key tool to monitor compliance of captive facilities, support tiger trade investigations and improve prosecution outcomes. Here, we present a standardised wildlife forensic DNA profiling system for captive tigers called TigerBase. TigerBase has been developed in four South-East Asia countries with captive tiger facilities: Malaysia, Vietnam, Thailand and Lao PDR. TigerBase DNA profile data is based on 60 single nucleotide polymorphism (SNP) markers, genotyped using two different TaqMan®-based approaches: OpenArray® chip (capable of genotyping 60 SNPs for 48 samples in a single chip), and singleplex TaqMan® assays (capable of genotyping one SNP for one sample per reaction). Of the 60 SNPs, 53 are autosomal nuclear markers, suitable for individualisation and parentage applications, two are sex-linked markers, suitable for sexing, and five are mtDNA markers, suitable for maternal subspecies identification. We conducted a series of validation experiments to investigate the reliability and limitations of these SNP genotyping platforms. We found that the OpenArray® chip platform is more appropriate for generating reference data given its greater throughput, while the singleplex TaqMan® assays are more appropriate for genotyping lower quality casework samples, given their higher sensitivity and throughput flexibility. Only 19 autosomal nuclear markers were validated as singleplex TaqMan® assays, which generally provides ample power for individualisation analysis (probability of identity among siblings was <6.9 ×10−4), but may lack power for specific parentage questions, such as determining parentage of an offspring when one of the parent’s genotypes is missing. Further, we have developed pipelines to support standardised SNP calling and decrease the chance of genotyping errors through the use of analytical workflows and synthetic positive controls. We expect the implementation of TigerBase will enhance enforcement of tiger trafficking cases and encourage compliance among captive tiger facilities, together contributing to combatting the illegal tiger trade.

An Analysis of Welfare Standards Within Tiger (Panthera tigris) Facilities in Thailand.

In Thailand, tigers are more numerous in captivity than they are in the wild, with 51 facilities housing approximately 1962 tigers. As charismatic fauna, tigers are popular with tourists, and the majority of facilities offer a variety of entertainment activities with controversial reports towards the animals' welfare. The aim of this research was to investigate tiger welfare in Thai zoos to identify specific welfare issues. We assessed 34 tourism facilities holding tigers in Thailand in 2019 using a 25-point welfare assessment that utilizes the Five Domain model (incorporating all five domains: nutrition, physical environment, health, behavioural interactions and mental state). The mental domain score was derived from the scores of the other four domains. Additional data were collected from each facility, including the number of tigers, any colour variants, types of human interaction and admission cost. Welfare scores for each domain were calculated by totalling the scores per domain and dividing by the number of points allocated to that domain. A multiple regression was used to identify any significant predictors of mental domain score. The results revealed that the provision of a suitable physical environment scored the lowest, while nutrition scored the highest though this was still a low score overall. The multiple regression showed that 45.4% of the variance for the mental domain score was significantly affected by the number of colour variants housed and the types of human interaction available with facilities, with more of both these factors contributing to a more negative score. Our results demonstrate the need for urgent, comprehensive infrastructural, species-appropriate environment and design and animal management improvements to increase animal welfare. Informed institutional change toward the breeding and use of tigers for public interactions is also required. This is the first assessment completed of captive tiger welfare of tiger facilities in Thailand and shows that the welfare concerns encountered are within a high proportion (67%) of Thailand's facilities. This supports the need for the creation and enforcement of effective and clear captive wildlife operational standards to provide a sustained solution for captive tiger welfare and can provide a considered approach to ex-situ tiger management that, in conjunction with in-situ efforts, can improve much needed conservation efforts of this species.

Gut Microbiota Plasticity and Metabolic Implications in Asian Tiger Populations

Gut Microbiota Plasticity and Metabolic Implications in Asian Tiger Populations

SERIAL CHANGES IN METABOLIC ACID-BASE STATUS IN THREE SPECIES OF ANESTHETIZED CAPTIVE LARGE FELID.

Determination of acid-base status contributes important information about patient health, including for patients under anesthesia. There is a paucity of information about the determinants of acid-base status of large felids managed under anesthesia, and advancement of such knowledge may contribute to patient safety. This study serially monitored the individual metabolic acid-base status of 11 large felids, including lions (Panthera leo), tigers (Panthera tigris), and cheetahs (Acinonyx jubatus), under general anesthesia. We analyzed the contributions of measured strong ions (sodium, chloride, potassium, lactate), weak acids and buffers (albumin, phosphate and bicarbonate), and unmeasured anions to standardized extracellular base excess (SBE). A general linear model assessed for species differences in these parameters, with time since immobilization, SBE, and mean arterial pressure as covariates. By employing a Stewart-based analytical approach, it was possible to separate chloremic and unmeasured anion contributions to metabolic acid base status. This provided a basis for identifying mixed metabolic processes, generating differentials for underlying causes. Using normal acid base parameters for domestic felids, metabolic acidosis was found to be prevalent. Frequent evidence of unmeasured anion accumulation was also found, with unmeasured anions occasionally exceeding 5mmol/L. These findings warrant further inquiry into the drivers and clinical significance of metabolic acidosis and unmeasured anion accumulations in anesthetized large felids, encouraging further anion identity studies to elucidate possible causes. Reference ranges need to be established for acid-base parameters in large felids as a foundation for interpreting more controlled, prospective research into determinants of metabolic acid-base status in these animals under anesthesia.

USE OF SOLENSIA (FRUNEVETMAB) IN NONDOMESTIC FELIDS (PANTHERA TIGRIS, LYNX RUFUS, PANTHERA UNCIA) GUIDED BY PROTEIN SEQUENCE ANALYSIS.

Osteoarthritis and degenerative joint disease affect many species of nondomestic felid and negatively impact quality of life in managed care settings. Previously, pain management options were limited because of the frequency of comorbidities such as renal disease and common difficulty encountered in medication administration. SolensiaTM (frunevetmab) is a felinized monoclonal antibody that binds to nerve growth factor in arthritic joints, thereby inhibiting pain response cascades, and produces marked improvement in clinical signs and quality of life in domestic cats diagnosed with osteoarthritis. Protein sequence analysis was performed to inform the application of frunevetmab in four individuals from three nondomestic felid species (Panthera tigris, Lynx rufus, and Panthera uncia) diagnosed with degenerative joint disease to predict safety, contraindications, and likely response to treatment. Patients were then treated utilizing doses extrapolated from domestic cats and following manufacturer guidelines for administration, and clinical response was evaluated over a minimum 2-mon period. Significant improvement was noted in clinical signs in all four animals, resulting in marked improvement in mobility, lameness, activity level, demeanor, and overall quality of life. Frunevetmab presents an excellent adjunctive therapeutic alternative for nondomestic felids suffering from degenerative joint disease and may complement or decrease the need for other conventional therapeutic regimens.

BILIARY DUCTAL PLATE MALFORMATION WITH SECONDARY PORTAL HYPERTENSION AND MULTIPLE ACQUIRED SHUNTS IN A LITTER OF AMUR TIGERS (PANTHERA TIGRIS ALTAICA).

Congenital abnormalities in tigers (Panthera tigris) are infrequently reported but have included ectrodactyly, cataracts, and vestibular disease. Primary hepatic disease has been documented in multiple nondomestic felid species but is considered uncommon in tigers. To the authors' knowledge, there are no previous reports of congenital abnormalities of the liver in tigers. In May 2022, two male Amur tiger cubs (Panthera tigris altaica) were born at a zoological institution via cesarean section to address dystocia, following the natural birth of a female cub. Between two and six months of age, all three cubs developed progressive lethargy, inappetence, and neurological signs consistent with hepatic encephalopathy, including obtundation and ataxia. In all three cases, serum biochemical values revealed progressive, marked elevations in hepatic enzyme levels with reduction in hepatic synthetic products (albumin, urea, cholesterol). Computed tomographic imaging showed a large cluster of aberrant tortuous vessels craniomedial to the left kidney in all three tigers, consistent with acquired extrahepatic portosystemic shunts. Histologic examination of the livers identified biliary ductal plate malformations. This report details the presentation, clinical findings, diagnoses, and therapeutic interventions attempted in three Amur tiger cubs with biliary ductal plate malformation and subsequent portal hypertension with multiple acquired portosystemic shunts, an unusual abnormality not previously reported in non-domestic felids.

Does presence of top predator improve forest birds' survival and diversity? An ecological case study assessing umbrella conservational impact of tiger using carrion

After hunting, predators tend to leave a large amount of carrion behind. It is widely reported that this resource is commonly used by various species in the ecosystem and is essential for the survival of scavengers, particularly in winter. Although recent studies are focused on mammals, little is known about how this works with facultative scavenger birds, which may lead to a serious underestimation of the key role that top predators such as the Amur tiger (Panthera tigris altaica) play in ecosystems. Here, we conducted a field feeding experiment to quantitatively evaluate the effects of Amur tiger on avian scavengers by simulating their predation residue. The results show that the Corvidae is the main bird species that consumes carrion, while woodpeckers and some insectivorous songbirds also benefit from the remains that Amur tiger leaves behind. We assumed that in winter, if the daily energy demand for the six main scavenger birds completely relied on the predation residues of Amur tiger separately, the prey remains of one Amur tiger could feed about 28 crows, 49 Azure-winged magpies, 61 Eurasian jays, 235 Eurasian nuthatches, 96 Great spotted woodpeckers, or 385 Willow tits. It means that the prey remains of top predators like Amur tiger may be an extremely important resource to avian scavengers and carrion could be a potential ecological indicator of Amur tiger keystone effect. This study provides experimental evidence from the field for the first time, and reveals the ecological mechanism of the role of keystone species of the Amur tiger, i.e., how to indirectly protect other animal groups in the forest ecosystem that have important ecological value for the biodiversity and the health of local forest vegetation through the protection of the Amur tiger.