Biodiversity and global land-use change in Bhutan: a model for the Himalayas

The eastern Himalayas are a global biodiversity hotspot with one of the highest rates of species endemism. But a high rate of habitat degradation and loss fuelled by anthropogenic disturbance and climate change is besieging biodiversity. Understanding the interaction between biodiversity and land-use change is particularly important in the context of the eastern Himalayan landscape in the face of global climate change. However, a synthesis of combined impacts of land use and climate change on biodiversity in this landscape is surprisingly rare. This thesis aims to fulfil that gap. In Chapter 2, using multi-scale models for terrestrial mammal communities, I show that protected areas (PA) and forest cover are the two most important variables associated with habitat use of most modelled species. Further, I show that both carnivores and herbivores are equally important umbrella species. The gap analysis shows that existing PAs and areas adjacent to them are crucial for overall species richness protection. Chapter 3 uses two spatially synoptic methods (i.e., resistant kernel density and factorial least cost path) to identify core habitats and corridors for terrestrial mammal communities. I show that Asian elephant (Elephas maximus) was the most effective umbrella species for the overall protection of core habitats. In terms of dispersal corridor protection, muntjac was the most effective umbrella species. Using cluster analysis, I identified six indicator species (Asian elephant, Asiatic black bear [Ursus thibetanus], clouded leopard [Neofelis nebulosa], dhole [Cuon alpinus], sambar deer [Rusa unicolor] and tiger [Panthera tigris]) for broad core habitat and corridor protection. Here, I show that dispersal is not just limited within PAs and the long-term viability of wildlife populations require habitats and corridors outside the existing PA network. In Chapter 4, I show that the realised functional space of the vertebrate groups (mammals and birds) is clumped around a small number of functional strategies. The loss of species at the edge of functional space is non-random and could result in the loss of irreplaceable traits impacting long-term ecological and evolutionary processes. Further, this study demonstrates the filtering effect of anthropogenic pressure and climate change on vertebrate functional and phylogenetic diversity. Chapter 5 demonstrates the complex effects of human settlement density on large carnivore interactions. I show that space-use patterns are driven by a combination of the behavioural mechanism of each species and its interactions with competing species. The duality of the effect of settlement density on species interactions suggests that the benefits of exploiting anthropogenic environments are a trade-off between ecological opportunity and the risk of conflict with humans. Taken together, this thesis highlights the importance of eastern Himalayan biodiversity and the need for integrated and synthetic research across the Himalayas to better understand the effects of anthropogenic land-use and climate change on distribution, connectivity, and behavioural ecology of terrestrial vertebrates and on the multiple facets of biodiversity per se

Vulnerability of mammal communities to the combined impacts of anthropic land-use and climate change in the Himalayan conservation landscape of Bhutan

Human land-use and climate change drive biodiversity loss, precipitating the extinction crisis. The fragility of the Himalayas makes species in this landscape vulnerable to land-use and climate change. We aim to quantify the response of terrestrial mammal community to land-use and climate scenarios in the Bhutan Himalaya. Using large-scale camera-trap dataset, we examine the effects of anthropic land-use and climate variables on the terrestrial mammal assemblage using Bayesian multi-species occupancy model. Most of the terrestrial mammals in our sample displayed a strong negative relationship with anthropic land-use variables (agriculture, roads and settlement). Further, the occurrence of most species decreased with likely projections for climate variables, illustrating threats to conservation if the current trend in global warming continues. Notably, we found that biodiversity conservation in this landscape can be achieved by protecting extensive forest cover. Our findings emphasize the importance of reconciling land-use management and mammal conservation in the face of climate change and provide vital information which can be used to optimize future conservation and development plans

Prioritizing areas for conservation outside the existing protected area network in Bhutan: the use of multi-species, multi-scale habitat suitability models

Context Understanding the environmental and anthropogenic factors influencing habitat selection of multiple species is a foundation for quantifying human impacts on biodiversity and developing effective conservation measures. Objectives To determine the effect of multiple scales of environmental/topographic and anthropogenic variables and landscape patterns on habitat suitability of terrestrial mammals in Bhutan, assess the effectiveness of the current protected area network, identify areas of high species richness outside of the existing protected area, and evaluate the potential effectiveness of indicator and umbrella species for conservation planning. Methods We modelled multi-scale habitat selection of sixteen species of terrestrial mammals across Bhutan using data from a nation-wide camera trap survey. We used the predicted species distribution maps to assess the multi-species conservation effectiveness of the existing protected area network. We performed simulations to identify high priority areas for multiple species based on their habitat suitability, proximity to existing protected areas and overall connectivity within the predicted distribution of species. We used correlation analysis among predicted occurrence maps and multivariate cluster analysis to identify potential indicator species. We evaluated the potential utility of each species as umbrella species by assessing how well optimal protected areas for that species would protect suitable habitat for all 16 species simultaneously. Results Protected areas and forest cover were strongly associated with habitat use of most modelled species. Additionally, topographical features, like terrain roughness and slope position, contributed to habitat selection of multiple species, but often in different ways. Environmental and topographical variables were mostly selected at medium to broad scales. Anthropogenic variables (agriculture and built-up areas) were negatively associated with habitat suitability of most species at both fine and broad scales. Conservation effectiveness assessment of existing protected areas found protected areas in south-central Bhutan have high effectiveness in terms of both mean and total richness protected. Similarly, biological corridors in the south-central region offered high mean richness protection. Our simulation of optimal areas for additional protection found areas abutting protected areas in southern Bhutan offered high relative species richness protection. Our umbrella species analysis found muntjac, wild pig, serow, sambar and Asian golden cat are the most effective umbrella species for broader biodiversity protection. Our indicator species analysis found tiger, gaur, dhole, clouded leopard, Asian black bear and common leopard as effective indicator species. Conclusions This study highlights the need to protect optimally located species-rich areas outside the current protected areas. This kind of multi-species habitat assessment provides important information to optimize future conservation and development plans at national and regional scales

Understanding the environmental and anthropogenic correlates of tiger presence in a montane conservation landscape

Management of tigers is a response to a global conservation crisis. Range contraction, population decline, habitat fragmentation, prey loss, and poaching cause and aggravate this crisis. There is a debate as to whether conserving source sites or maintaining landscape connectivity is the greater priority. Both approaches rely on understanding environmental and anthropogenic factors. We used a large dataset from a nation-wide camera trapping survey to investigate factors affecting habitat use of tigers across the montane landscape of Bhutan. We tested the effects of environmental and anthropogenic covariates on habitat use while accounting for imperfect detection using a hierarchical occupancy model. Tiger habitat use showed a strong positive association with closeness to protected area, greater distance from human settlement and availability of abundant large prey. Our findings can help to identify the drivers of tiger decline and contribute to the refinement of conservation strategies to combat that decline in this montane conservation landscape. We provide a general approach to tiger conservation by highlighting the importance of understanding the basic ecology of this apex predator, including the relationship between environmental and anthropogenic variables and habitat use. Bhutan, with unusually strong environmental legislation, and a high percentage of its area protected and under contiguous forest cover, set the global standard in large carnivore conservation and is an important component of a wider conservation complex in South Asia

Identifying important conservation areas for the clouded leopard Neofelis nebulosa in a mountainous landscape: Inference from spatial modeling techniques

The survival of large carnivores is increasingly precarious due to extensive human development that causes the habitat loss and fragmentation. Habitat selection is in-fluenced by anthropogenic as well as environmental factors, and understanding these relationships is important for conservation management. We assessed the en-vironmental and anthropogenic variables that influence site use of clouded leopard Neofelis nebulosa in Bhutan, estimated their population density, and used the results to predict the species’ site use across Bhutan. We used a large camera-trap dataset from the national tiger survey to estimate for clouded leopards, for the first time in Bhutan, (1) population density using spatially explicit capture–recapture models and (2) site-use probability using occupancy models accounting for spatial autocorrela-tion. Population density was estimated at ̂DBayesian=0.40 (0.10 SD) and ̂Dmaximum−likelihood=0.30 (0.12 SE) per 100 km2. Clouded leopard site use was positively associated with forest cover and distance to river while negatively associated with elevation. Mean site-use probability (from the Bayesian spatial model) was ̂ψspatial=0.448 (0.076 SD). When spatial autocorrelation was ignored, the probability of site use was overestimated, ̂ψnonspatial=0.826 (0.066 SD). Predictive mapping al-lowed us to identify important conservation areas and priority habitats to sustain the future of these elusive, ambassador felids and associated guilds. Multiple sites in the south, many of them outside of protected areas, were identified as habitats suitable for this species, adding evidence to conservation planning for clouded leopards in continental South Asia

Contrasting effects of human settlement on the interaction among sympatric apex carnivores

In the face of a growing human footprint, understanding interactions among threatened large carnivores is fundamental to effectively mitigating anthropogenic threats and managing species. Using data from a large-scale camera trap survey, we investigated the effects of environmental and anthropogenic variables on the interspecific interaction of a carnivore guild comprising of tiger, leopard, and dhole in Bhutan. We demonstrate the complex effects of human settlement density on large carnivore interactions. Specifically, we demonstrate that leopard-dhole co-occupancy probability was higher in areas with higher human settlement density. The opposite was true for tiger-leopard co-occupancy probability, but it was positively affected by large prey (gaur) abundance. These findings suggest that multi carnivore communities across land-use gradients are spatially structured and mediated also by human presence and/or the availability of natural prey. Our findings show that space-use patterns are driven by a combination of the behavioural mechanism of each species and its interactions with competing species. The duality of the effect of settlement density on species interactions suggests that the benefits of exploiting anthropogenic environments are a trade42 off between ecological opportunity (food subsidies or easy prey) and the risk of escalating conflict with humans

Current trends suggest most Asian countries are unlikely to meet future biodiversity targets on protected areas

Aichi Target 11 committed governments to protect ≥17% of their terrestrial environments by 2020, yet it was rarely achieved, raising questions about the post-2020 Global Biodiversity Framework goal to protect 30% by 2030. Asia is a challenging continent for such targets, combining high biodiversity with dense human populations. Here, we evaluated achievements in Asia against Aichi Target 11. We found that Asia was the most underperforming continent globally, with just 13.2% of terrestrial protected area (PA) coverage, averaging 14.1 ± SE 1.8% per country in 2020. 73.1% of terrestrial ecoregions had <17% representation and only 7% of PAs even had an assessment of management effectiveness. We found that a higher agricultural land in 2015 was associated with lower PA coverage today. Asian countries also showed a remarkably slow average annual pace of 0.4 ± SE 0.1% increase of PA extent. These combined lines of evidence suggest that the ambitious 2030 targets are unlikely to be achieved in Asia unless the PA coverage to increase 2.4-5.9 times faster. We provided three recommendations to support Asian countries to meet their post-2020 biodiversity targets: complete reporting and the wider adoption “other effective area-based conservation measures”; restoring disturbed landscapes; and bolstering transboundary PAs

Density and occupancy of leopard cats across different forest types in Cambodia

The leopard cat (Prionailurus bengalensis) is the most common wild felid in Southeast Asia, yet little is known about the factors that affect their population density and occupancy in natural habitats. Although leopard cats are highly adaptable and reportedly can attain high densities in human-modified habitats, it is not clear which natural habitat is optimal for the species. Also, this felid has been preyed upon by large carnivores in Southeast Asia, yet the intra-guild effects of large carnivore presence on leopard cats are almost unknown. To shed light on these fundamental questions, we used data from camera trap surveys for felids to determine the leopard cat densities in three different forest types within Cambodia: continuous evergreen, mosaic dominated by evergreen (hereafter evergreen mosaic), and mosaic dominated by open dry deciduous forests (hereafter DDF mosaic). We also conducted occupancy analyses to evaluate the interactions of the leopard cats with three large carnivores: leopards (Panthera pardus), dholes (Cuon alpinus), and domestic dogs (Canis familiaris). The estimated density (individuals/100 km2 ± SE) was highest in the continuous evergreen (27.83 ± 7.68), followed by evergreen mosaic (22.06 ± 5.35) and DDF mosaic (13.53 ± 3.23). Densities in all three forest types were relatively high compared to previous studies. Domestic dogs were detected on all 3 sites, and leopards and dholes had sufficient records on only one site each. The occupancy probability of leopard cats was not affected by the presence or absence of any large carnivore, indicating that large carnivores and leopard cats occurred independently of each other. Our findings support the claim that leopard cats are habitat generalists, but we show that evergreen forest is the optimum natural habitat for this species in the region. The DDF mosaic appears to sustain lower densities of leopard cats, probably due to the harsh dry season and wildfires that led to reduced prey base, although this generalist felid was still able to occupy DDF in relatively moderate numbers. Overall, the adaptability of leopard cats to various forest types, and lack of negative interaction with large carnivores, helps to explain why this species is the most common and widespread felid in Southeast Asia

Multi-scale habitat modelling identifies spatial conservation priorities for mainland clouded leopards (Neofelis nebulosa)

Diversity and Distributions Published by John Wiley &amp; Sons Ltd. Aim: Deforestation is rapidly altering Southeast Asian landscapes, resulting in some of the highest rates of habitat loss worldwide. Among the many species facing declines in this region, clouded leopards rank notably for their ambassadorial potential and capacity to act as powerful levers for broader forest conservation programmes. Thus, identifying core habitat and conservation opportunities are critical for curbing further Neofelis declines and extending umbrella protection for diverse forest biota similarly threatened by widespread habitat loss. Furthermore, a recent comprehensive habitat assessment of Sunda clouded leopards (N. diardi) highlights the lack of such information for the mainland species (N. nebulosa) and facilitates a comparative assessment. Location: Southeast Asia. Methods: Species–habitat relationships are scale-dependent, yet &lt;5% of all recent habitat modelling papers apply robust approaches to optimize multivariate scale relationships. Using one of the largest camera trap datasets ever collected, we developed scale-optimized species distribution models for two con-generic carnivores, and quantitatively compared their habitat niches. Results: We identified core habitat, connectivity corridors, and ranked remaining habitat patches for conservation prioritization. Closed-canopy forest was the strongest predictor, with ~25% lower Neofelis detections when forest cover declined from 100 to 65%. A strong, positive association with increasing precipitation suggests ongoing climate change as a growing threat along drier edges of the species’ range. While deforestation and land use conversion were deleterious for both species, N. nebulosa was uniquely associated with shrublands and grasslands. We identified 800 km2 as a minimum patch size for supporting clouded leopard conservation. Main conclusions: We illustrate the utility of multi-scale modelling for identifying key habitat requirements, optimal scales of use and critical targets for guiding conservation prioritization. Curbing deforestation and development within remaining core habitat and dispersal corridors, particularly in Myanmar, Laos and Malaysia, is critical for supporting evolutionary potential of clouded leopards and conservation of associated forest biodiversity

Multi-scale habitat modelling identifies spatial conservation priorities for mainland clouded leopards (Neofelis nebulosa)

Diversity and Distributions Published by John Wiley and Sons Ltd. Aim: Deforestation is rapidly altering Southeast Asian landscapes, resulting in some of the highest rates of habitat loss worldwide. Among the many species facing declines in this region, clouded leopards rank notably for their ambassadorial potential and capacity to act as powerful levers for broader forest conservation programmes. Thus, identifying core habitat and conservation opportunities are critical for curbing further Neofelis declines and extending umbrella protection for diverse forest biota similarly threatened by widespread habitat loss. Furthermore, a recent comprehensive habitat assessment of Sunda clouded leopards (N. diardi) highlights the lack of such information for the mainland species (N. nebulosa) and facilitates a comparative assessment. Location: Southeast Asia. Methods: Species–habitat relationships are scale-dependent, yet <5% of all recent habitat modelling papers apply robust approaches to optimize multivariate scale relationships. Using one of the largest camera trap datasets ever collected, we developed scale-optimized species distribution models for two con-generic carnivores, and quantitatively compared their habitat niches. Results: We identified core habitat, connectivity corridors, and ranked remaining habitat patches for conservation prioritization. Closed-canopy forest was the strongest predictor, with ~25% lower Neofelis detections when forest cover declined from 100 to 65%. A strong, positive association with increasing precipitation suggests ongoing climate change as a growing threat along drier edges of the species’ range. While deforestation and land use conversion were deleterious for both species, N. nebulosa was uniquely associated with shrublands and grasslands. We identified 800 km2 as a minimum patch size for supporting clouded leopard conservation. Main conclusions: We illustrate the utility of multi-scale modelling for identifying key habitat requirements, optimal scales of use and critical targets for guiding conservation prioritization. Curbing deforestation and development within remaining core habitat and dispersal corridors, particularly in Myanmar, Laos and Malaysia, is critical for supporting evolutionary potential of clouded leopards and conservation of associated forest biodiversity