Foraging ecology and coexistence of Asiatic black bears and sun bears in a seasonal tropical forest in Southeast Asia

Correlates and impacts of human-mammal conflict in the central part of Chitwan Annapurna Landscape, Nepal

Crop damage, predation on domestic animals and human attacks are often associated with human-wildlife conflict. The abundance and encounter rate of wild mammals are often associated with human wildlife conflict. Crop damage, livestock depredation and human injury and their relation with environmental factors and encounter rate of the mammals was evaluated in the central region of Chitwan Annapurna Landscape. The abundance and the encounter rate of large mammals were determined by dividing the study area into four different study blocks (A, B, C and D) based on river course and topography. A total of 150 transects (average length = 3.18 ± 0.11 km), were administrated for data collection. Similarly, information on human-wildlife conflict was collected using 600 semi-structured questionnaires (150 from each block). The chital was the most abundant mammal (encounter rate (ER) = 1.49 and relative abundance (RA) = 55.45%) in block A whereas muntjac had the highest encounter rate in blocks B, C and D (ER = 0.34, 0.31, 0.79 respectively) but the relative abundance of rhesus was comparatively higher in blocks B, C and D. The signs of tiger were reported from block A only whereas signs of leopard were reported from all blocks. But signs of Himalayan black bear were reported from B, C and D. The encounter rate of the mammals correlated with the monetary loss caused by them. Greater one-horned rhino, wild pig and chital in lowland and monkeys, northern red muntjac, and Himalayan black bear in mid-hills (blocks B, C and D) were the principal crop raiders with a total average annual loss of US$ 11.45 per household. Similarly, the total annual monetary loss by livestock depredation was US$ 76.60 per household. This study evaluated the encounter rate of mammals and their effects on the conflict with people. However, the negative effects arrived from human-wildlife conflicts always threaten large mammals. Hence, this study suggests future intensive studies related to mitigation and prevention methods to mitigate the issues of human-wildlife conflicts.

Lithocarpustapanuliensis (Fagaceae), a new stone oak from northern Sumatra and its role as an important resource for critically endangered orangutans

A new species of stone oak, Lithocarpustapanuliensis Harapan, W.H.Tan, Nurainas & Strijk from South Tapanuli, North Sumatra, Indonesia is described. We provide colour photographs, a distribution map and a new IUCN conservation status assessment for inclusion on the global Red List. The unique cupule morphology, particularly the shape, placement and distinctness of the cupule protuberances, are distinctive from other Lithocarpus species in the region. Ecological interactions (e.g. consumption and nesting) with Tapanuli orangutans were recorded in the field.

Coexistence patterns of sympatric giant pandas (Ailuropoda melanoleuca) and Asiatic black bears (Ursus thibetanus) in Changqing National Nature Reserve, China

Similar species may co-occur in sympatry because of the partitioning of habitat use and resources at different spatial and temporal scales. Understanding coexistence patterns of species may contribute to further uncovering the underlying coexistence mechanisms, and ultimately benefit the conservation of threatened species. In this study, camera trapping was used to investigate spatial and temporal activity patterns of sympatric giant pandas (Ailuropoda melanoleuca) and Asiatic black bears (Ursus thibetanus) in Changqing National Nature Reserve in Qinling Mountains, China. Our study obtained 281 independent detections of giant pandas and 185 of Asiatic black bears during 93,606 camera-trap days from April 2014 to October 2017. We performed occupancy modeling and temporal overlap analyses to examine the spatial-temporal relationships between pandas and bears, and results showed that: (1) giant pandas had higher detection probabilities than Asiatic black bears, while having lower occupancy probabilities; (2) Elevation positively predicted giant panda and negatively predicted Asiatic black bear occupancy, understory vegetation type negatively predicted giant panda occupancy, and distance to nearest settlement positively predicted Asiatic black bear occupancy; (3) giant pandas were more active in spring and winter, while Asiatic black bears were more active in summer, and the two species had low spatial overlap with one another throughout the year; (4) both giant pandas and Asiatic black bears showed mainly diurnal activity patterns, and had high temporal overlap with one another in spring and moderate temporal overlap with one another in autumn. Our results provide detailed information of the spatial and temporal ecology of sympatric giant pandas and Asiatic black bears in the Qinling Mountains of China, which could act as a guide to construct conservation priorities as well as design efficient management programs.

Activity patterns of Asiatic black bear (Ursus thibetanus) in the moist temperate forests of Machiara National Park, Azad Jammu and Kashmir, Pakistan

The Asiatic black bear (Ursus thibetanus) is an environmental indicator species whose activity patterns may be highly impacted by habitat changes. We monitored the monthly and daily activity patterns of black bears in the moist temperate forests of Machiara National Park. We used infrared camera traps and local ecological knowledge for data collection from April 2019 to April 2021. Camera traps recorded 109 [inside forest = 107, outside forest (near crop fields and human settlements) = 2] independent registrations (IR) in 5541 (692.63 ± 36.72, mean ± SD) camera days. We found (i) spring and autumn to be the lowest activity seasons for black bears inside the forest. (ii) The highest activity was recorded in summer, with a peak in August followed closely by July. (iii) The activity level sharply declined after August and halted from December to March, indicative of the bears' hibernation period. Local knowledge revealed that (i) bears remained active from May to November and hibernated the rest of the period. (ii) Bear activity was at its peak inside the forest in summer and outside the forest in autumn when bears sought to raid the widely cultivated maize crop (Zea mays) planted along forest edges. This increased activity outside of the forest is likely driven by decreased food availability inside the forest area and maize crop being a preferred anthropogenic food type for bears. Based on the daily activity pattern, bears exhibited cathemeral behavior (i.e., active throughout the day) with maximum overlap between camera trap and local ecological knowledge data. Human activity may be impacting the daily activity patterns of bears via disturbance and interference. The data collected in this study can help mitigate conflicts between humans and black bears and consequently assist in future conservation of black bears in the area.

Understanding Species–Habitat Associations: A Case Study with the World’s Bears

Habitat modeling is one of the most common practices in ecology today, aimed at understanding complex associations between species and an array of environmental, bioclimatic, and anthropogenic factors. This review of studies of seven species of terrestrial bears (Ursidae) occupying four continents examines how habitat models have been employed, and the functionality of their predictions for management and conservation. Bear occurrence data have been obtained at the population level, as presence points (e.g., sign surveys or camera trapping), or as locations of individual radio-collared animals. Radio-collars provide greater insights into how bears interact with their environment and variability within populations; they are more commonly used in North America and Europe than in South America and Asia. Salient problematic issues apparent from this review included: biases in presence data; predictor variables being poor surrogates of actual behavioral drivers; predictor variables applied at a biologically inappropriate scale; and over-use of data repositories that tend to detach investigators from the species. In several cases, multiple models in the same area yielded different predictions; new presence data occurred outside the range of predicted suitable habitat; and future range projections, based on where bears presently exist, underestimated their adaptability. Findings here are likely relevant to other taxa.

First attempt at rehabilitation of Asiatic Black Bear cubs to the wild in Thailand

Returning orphan bear cubs to the wild can benefit bear welfare and conservation but is hindered in Asia by the scarcity of documented experience.  We experimented with rehabilitation of two Asiatic Black Bear cubs in Thailand using the assisted method of soft-release.  We raised the 5-month old cubs for 11 months with minimal human contact in a remote enclosure in high quality habitat, letting cubs out periodically to walk with caretakers in the forest.  The caretakers acted as surrogate mothers, allowing cubs to safely acquire foraging skills and familiarity with the forest.  Supplementary feeding resulted in the cubs’ rapid weight gain (average 157g/day), faster than would occur in the wild.  Faster growth allowed the cubs to be released sooner, reducing the likelihood of long-term habituation.  After three months of rehabilitation, the bear cubs started showing signs of being wary of the caretakers (e.g., cautious when we approached their enclosure) and their focus during walks switched from play to foraging.  After seven months they began to spend nights away from their enclosure, thus declining the supplemental food.  This sequence and timing of increasing separation and independence from people matched other assisted soft releases in the region.  The cubs went missing in month 12, shortly before planned collaring and release. They were seen together 2.5 months later on a fruiting tree and ran away when approached.  Assisted soft releases might be a promising option for bear rehabilitation in Asia but more data are needed to evaluate their effectiveness relative to other methods.  This method affords direct observations of bears in the wild that can augment our knowledge of bear behavior and ecology.

Activity pattern study of Asiatic black bear (Ursus thibetanus) in the Qinling Mountains, China, by using infrared camera traps

The study of activity patterns is important for understanding the capacity of animals for adapting their behavior based on their habitat conditions. Among bears, daily activity patterns are considered to be strongly influenced by regional climate conditions. We monitored the activity patterns (active vs. inactive) of the Asiatic black bear (Ursus thibetanus) using infrared camera traps (from May 2013 to November 2016) in the Qinling Mountains, China. We used 125 photos, with 19,132 camera days from 55 camera locations. Based on relative independent capture (RIC), bears were found to be intensively active during June (5.86 ± 1.05 SE), July (8.45 ± 2.74), September (14.83 ± 6.13), and October (8.70 ± 3.43), with activity levels gradually decreasing beyond October. After this decline, activities eventually come to a halt when the bears enter in hibernation. We found that their hibernation period was shorter in the Qinling bears, with only 3 months of denning from January to March. Based on their daily patterns, bears were predominantly active during the daytime both in spring (70.83 ± 35.41%) and summer (52.09 ± 28.89%), but more active at twilight during autumn (51.12 ± 42.88%). We assumed that food preferences and food availability (due to warmer regional climatic conditions) might be responsible for such deviations in daily and monthly activity patterns.

Epidemiology and pathological progression of erythematous lip lesions in captive sun bears (Helarctos malayanus)

This study investigates the occurrence of erythematous lip lesions in a captive sun bear population in Cambodia, including the progression of cheilitis to squamous cell carcinoma, and the presence of Ursid gammaherpesvirus 1. Visual assessment conducted in 2015 and 2016 recorded the prevalence and severity of lesions. Opportunistic sampling for disease testing was conducted on a subset of 39 sun bears, with histopathological examination of lip and tongue biopsies and PCR testing of oral swabs and tissue biopsies collected during health examinations. Lip lesions were similarly prevalent in 2015 (66.0%) and 2016 (68.3%). Degradation of lip lesion severity was seen between 2015 and 2016, and the odds of having lip lesions, having more severe lip lesions, and having lip lesion degradation over time, all increased with age. Cheilitis was found in all lip lesion biopsies, with histological confirmation of squamous cell carcinoma in 64.5% of cases. Single biopsies frequently showed progression from dysplasia to neoplasia. Eighteen of 31 sun bears (58.1%) had at least one sample positive for Ursid gammaherpesvirus 1. The virus was detected in sun bears with and without lip lesions, however due to case selection being strongly biased towards those showing lip lesions it was not possible to test for association between Ursid gammaherpesvirus 1 and lip squamous cell carcinoma. Given gammaherpesviruses can play a role in cancer development under certain conditions in other species, we believe further investigation into Ursid gammaherpesvirus 1 as one of a number of possible co-factors in the progression of lip lesions to squamous cell carcinoma is warranted. This study highlights the progressively neoplastic nature of this lip lesion syndrome in sun bears which has consequences for captive and re-release management. Similarly, the detection of Ursid gammaherpesvirus 1 should be considered in pre-release risk analyses, at least until data is available on the prevalence of the virus in wild sun bears.

The distribution of plant consumption traits across habitat types and the patterns of fruit availability suggest a mechanism of coexistence of two sympatric frugivorous mammals

Understanding the mechanisms governing the coexistence of organisms is an important question in ecology, and providing potential solutions contributes to conservation science. In this study, we evaluated the contribution of several mechanisms to the coexistence of two sympatric frugivores, using western lowland gorillas (Gorilla gorilla gorilla) and central chimpanzees (Pan troglodytes troglodytes) in a tropical rainforest of southeast Cameroon as a model system. We collected great ape fecal samples to determine and classify fruit species consumed; we conducted great ape nest surveys to evaluate seasonal patterns of habitat use; and we collected botanical data to investigate the distribution of plant species across habitat types in relation to their "consumption traits" (which indicate whether plants are preferred or fallback for either gorilla, chimpanzee, or both). We found that patterns of habitat use varied seasonally for both gorillas and chimpanzees and that gorilla and chimpanzee preferred and fallback fruits differed. Also, the distribution of plant consumption traits was influenced by habitat type and matched accordingly with the patterns of habitat use by gorillas and chimpanzees. We show that neither habitat selection nor fruit preference alone can explain the coexistence of gorillas and chimpanzees, but that considering together the distribution of plant consumption traits of fruiting woody plants across habitats as well as the pattern of fruit availability may contribute to explaining coexistence. This supports the assumptions of niche theory with dominant and subordinate species in heterogeneous landscapes, whereby a species may prefer nesting in habitats where it is less subject to competitive exclusion and where food availability is higher. To our knowledge, our study is the first to investigate the contribution of plant consumption traits, seasonality, and habitat heterogeneity to enabling the coexistence of two sympatric frugivores.

OPEN RESEARCH BADGES

This article has earned an Open Data Badge for making publicly available the digitally-shareable data necessary to reproduce the reported results. The data is available at https://datadryad.org/resource/doi:10.5061/dryad.ms65f29.

Eco-evolutionary causes and consequences of temporal changes in intratumoural blood flow

Temporal changes in blood flow are commonly observed in malignant tumours, but the evolutionary causes and consequences are rarely considered. We propose that stochastic temporal variations in blood flow and microenvironmental conditions arise from the eco-evolutionary dynamics of tumour angiogenesis in which cancer cells, as individual units of selection, can influence and respond only to local environmental conditions. This leads to new vessels arising from the closest available vascular structure regardless of the size or capacity of this parental vessel. These dynamics produce unstable vascular networks with unpredictable spatial and temporal variations in blood flow and microenvironmental conditions. Adaptations of evolving populations to temporally varying environments in nature include increased diversity, greater motility and invasiveness, and highly plastic phenotypes, allowing for broad metabolic adaptability and rapid shifts to high rates of proliferation and profound quiescence. These adaptive strategies, when adopted in cancer cells, promote many commonly observed phenotypic properties including those found in the stem phenotype and in epithelial-to-mesenchymal transition. Temporal variations in intratumoural blood flow, which occur through the promotion of cancer cell phenotypes that facilitate both metastatic spread and resistance to therapy, may have substantial clinical consequences.