3,744 research outputs found

    Where will the dhole survive in 2030? Predicted strongholds in mainland Southeast Asia

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    Dhole (Cuon alpinus) is threatened with extinction across its range due to habitat loss and prey depletion. Despite this, no previous study has investigated the distribution and threat of the species at a regional scale. This lack of knowledge continues to impede conservation planning for the species. Here we modeled suitable habitat using presence-only camera trap data for dhole and dhole prey species in mainland Southeast Asia and assessed the threat level to dhole in this region using an expert-informed Bayesian Belief Network. We integrated prior information to identify dhole habitat strongholds that could support populations over the next 50 years. Our habitat suitability model identified forest cover and prey availability as the most influential factors affecting dhole occurrence. Similarly, our threat model predicted that forest loss and prey depletion were the greatest threats, followed by local hunting, non-timber forest product collection, and domestic dog incursion into the forest. These threats require proactive resource management, strong legal protection, and cross-sector collaboration. We predicted <20% of all remaining forest cover in our study area to be suitable for dhole. We then identified 17 patches of suitable forest area as potential strongholds. Among these patches, Western Forest Complex (Thailand) was identified as the region's only primary stronghold, while Taman Negara (Malaysia), and northeastern landscape (Cambodia) were identified as secondary strongholds. Although all 17 patches met our minimum size criteria (1667 km(2)), patches smaller than 3333 km(2) may require site management either by increasing the ecological carrying capacity (i.e., prey abundance) or maintaining forest extent. Our proposed interventions for dhole would also strengthen the conservation of other co-occurring species facing similar threats. Our threat assessment technique of species with scarce information is likely replicable with other endangered species

    Orbital Polarons in the Metal-Insulator Transition of Manganites

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    The metal-insulator transition in manganites is strongly influenced by the concentration of holes present in the system. Based upon an orbitally degenerate Mott-Hubbard model we analyze two possible localization scenarios to account for this doping dependence: First, we rule out that the transition is initiated by a disorder-order crossover in the orbital sector, showing that its effect on charge mobility is only small. Second, we introduce the idea of orbital polarons originating from a strong polarization of orbitals in the vicinity of holes. Considering this direct coupling between charge and orbital degree of freedom in addition to lattice effects we are able to explain well the phase diagram of manganites for low and intermediate hole concentrations

    Periodic One-Dimensional Hopping Model with one Mobile Directional Impurity

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    Analytic solution is given in the steady state limit for the system of Master equations describing a random walk on one-dimensional periodic lattices with arbitrary hopping rates containing one mobile, directional impurity (defect bond). Due to the defect, translational invariance is broken, even if all other rates are identical. The structure of Master equations lead naturally to the introduction of a new entity, associated with the walker-impurity pair which we call the quasi-walker. The velocities and diffusion constants for both the random walker and impurity are given, being simply related to that of the quasi-particle through physically meaningful equations. Applications in driven diffusive systems are shown, and connections with the Duke-Rubinstein reptation models for gel electrophoresis are discussed.Comment: 31 LaTex pages, 5 Postscript figures included, to appear in Journal of Statistical Physic

    Evidences of Interaction Homo-Cuon in three Upper Pleistocene Sites of the Iberian Mediterranean Central Region

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    Several cuon bones were discovered recently in three Upper Pleistocene archeological sites in the central area of the Iberian Mediterranean. This has proved that there were different types of interactions between dholes and prehistoric human groups. Firstly, evidence found in the archeological sites of Cova Negra and Coves de Santa Maira shows the use of carcasses of dholes by human hunter-gatherers. Secondly, the dhole remains recovered in Cova del Parpalló shows the dholes and humans could occupy the same habitat. In this case, the dhole died by natural causes in a small and isolated gallery before the human groups occupied the cave during the gravettian period. Associated with the dhole bones, there were also many ungulate mammal remains found. Some of these bones shows carnivore tooth marks. Due to these findings, we can presume that the dhole might have been the predator responsible for the bones discovered within the chamber. With the data provided we can come to the conclusion that this species had a more prominent role than we originally thought

    Photographic evidence of dholes in Gunung Gede Pangrango National Park, Indonesia.

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    For many years the dhole was believed to have been undetected in Gunung Gede Pangrango National Park (GGPNP). Nevertheless, in 2012 and 2013, we were able to photograph this elusive creature. We report the photographic evidence of the endangered dhole (Cuon alpinus) using camera trap di GGPNP.

    On a Dhole trail: examining ecological and anthropogenic correlates of Dhole habitat occupancy in the Western Ghats of India

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    Although they play a critical role in shaping ecological communities, many threatened predator species are data-deficient. The Dhole Cuon alpinus is one such rare canid with a global population thought to be < 2500 wild individuals. We assessed habitat occupancy patterns of dholes in the Western Ghats of Karnataka, India, to understand ecological and anthropogenic determinants of their distribution and habitat-use. We conducted spatially replicated detection/non-detection surveys of dhole signs along forest trails at two appropriate scales: the entire landscape and a single wildlife reserve. Landscape-scale habitat occupancy was assessed across 38,728 km2 surveying 206 grid cells of 188-km2 each. Finer scale habitat-use within 935 km2 Bandipur Reserve was studied surveying 92 grid cells of 13-km2 km each. We analyzed the resulting data of dhole signs using likelihood-based habitat occupancy models. The models explicitly addressed the problematic issue of imperfect detection of dhole signs during field surveys as well as potential spatial auto-correlation between sign detections made on adjacent trail segments. We show that traditional ‘presence versus absence’ analyses underestimated dhole habitat occupancy by 60% or 8682 km2 [naïve  =  0.27; ≏ ψL (SE) =  0.68 (0.08)] in the landscape. Addressing imperfect sign detections by estimating detection probabilities [ˆpt(L) (SE)  =  0.12 (0.11)] was critical for reliable estimation. Similar underestimation occurred while estimating habitat-use probability at reserve-scale [naïve  =  0.39; ˆψs (SE) =  0.71 (0.06)]. At landscape scale, relative abundance of principal ungulate prey primarily influenced dhole habitat occupancy. Habitat-use within a reserve, however, was predominantly and negatively influenced by anthropogenic disturbance. Our results are the first rigorous assessment of dhole occupancy at multiple spatial scales with potential conservation value. The approach used in this study has potential utility for cost-effectively assessing spatial distribution and habitat-use in other species, landscapes and reserves

    The Overlap Package

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    Camera traps - cameras linked to detectors so that they fire when an animal is present - are a major source of information on the abundance and habitat preferences of rare or shy forest animals. Modern cameras record the time of the photo, and the use of this to investigate diel activity patterns was immediately recognised (Gri?ffiths and van Schaik, 1993). Initially this resulted in broad classfication of taxa as diurnal, nocturnal, crepuscular, or cathemeral (van Schaik and Gri?ths, 1996). More recently, researchers have compared activity patterns among species to see how overlapping patterns may relate to competition or predation (Linkie and Ridout, 2011; Carver et al., 2011; Ramesh et al., 2012; Carter et al., 2012; Kamler et al., 2012; Ross et al., 2013). Ridout and Linkie (2009) presented methods to fit kernel density functions to times of observations of animals and to estimate the coe?cient of overlapping, a quantitative measure ranging from 0 (no overlap) to 1 (identical activity patterns). The code they used forms the basis of the overlap package. Although motivated by the analysis of camera trap data, overlap could be applied to data from other sources such as data loggers, provided data collection is carried out around the clock. Nor is it limited to diel cycles: tidal cycles or seasonal cycles, such as plant flowering or fruiting or animal breeding seasons could also be investigated
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