Providing more protected space for tigers Panthera tigris : a landscape conservation approach in the Western Ghats, southern India

Advances and challenges in ecological connectivity science

Maintaining and restoring ecological connectivity will be key in helping to prevent and reverse the loss of biodiversity. Fortunately, a growing body of research conducted over the last few decades has advanced our understanding of connectivity science, which will help inform evidence-based connectivity conservation actions. Increases in data availability and computing capacity have helped to dramatically increase our ability to model functional connectivity using more sophisticated models. Keeping track of these advances can be difficult, even for connectivity scientists and practitioners. In this article, we highlight some key advances from the past decade and outline many of the remaining challenges. We describe the efforts to increase the biological realism of connectivity models by, for example, isolating movement behaviors, population parameters, directional movements, and the effects of climate change. We also discuss considerations of when to model connectivity for focal or multiple species. Finally, we reflect on how to account for uncertainty and increase the transparency and reproducibility of connectivity research and discuss situations where decisions may require forgoing sophistication for more simple approaches.

Determinants of habitat occupancy and spatial segregation of primates in the central Western Ghats, India

Primates are among the globally imperiled fauna requiring urgent conservation interventions to protect their habitat. Information on species distribution and factors influencing it are vital to species management and habitat protection. In this study, we assessed habitat occupancy of the lion-tailed macaque (Macaca silenus), bonnet macaque (M. radiata), and black-footed gray langur (Semnopithecus hypoleucos) that occur in the Kudremukh Wildlife Division, a large protected area network in the central Western Ghats. We examined the influence of habitat variables on the occupancy probability of these primates. We carried out four temporally replicated detection/non-detection surveys to assess detection probability and site occupancy of the primate species. We surveyed 244 sites of 5 Km², with each site surveyed for 4 days, to assess detection probability and site occupancy. Among the three species, the langur had the highest habitat occupancy estimate (0.66 ± 0.05_SE) and the lion-tailed macaque had the lowest estimate (0.28 ± 0.08_SE). The habitat occupancy estimate for the bonnet macaque was (0.56 ± 0.05_SE)_. Wet and semi-evergreen forest cover and mean elevation positively influenced the lion-tailed macaque's occurrence. Covariates influencing bonnet macaque's occurrence were plantations, semi-evergreen and moist deciduous forests, and non-forest areas. Mean elevation negatively affected its occurrence. Wet evergreen forests and plantations positively influenced the occurrence of the langur. We examined spatial segregation between the species based on their site occupancy. Pairwise comparisons revealed a significant negative association between the bonnet macaque and the other two primates. However, we found a significant positive association between the lion-tailed macaque and the langur. We discuss these results and their implications for conservation of primates in the region. Given the cost-effectiveness of carrying out surveys at large spatial scales, we recommend occupancy surveys for future surveys of forest primates.

Effects of faecal inorganic content variability on quantifying glucocorticoid and thyroid hormone metabolites in large felines: Implications for physiological assessments in free-ranging animals

Faecal glucocorticoid (GC) and triiodothyronine (T3) metabolites and their interactions are increasingly used to monitor perceived stress and nutritional challenges in free-ranging animals. However, a number of extrinsic and intrinsic factors including hormone-inert dietary materials, inorganic matters etc. are known to affect reliable hormone metabolite quantifications. In this study, the impacts of inorganic matter (IOM) on faecal GC (fGCMs) and T3 (fT3Ms) metabolite measure were addressed in wild tiger (n = 193 from Terai Arc landscape, India) and captive lion (n = 120 from Sakkarbaug Zoological Garden, Gujarat, India) and possible corrective measures were evaluated. The wild tiger samples contained highly variable IOM content (9-98%, mostly with > 40% IOM) compared to captive Asiatic lion (17-57%, majority with < 40% IOM). Significant correlations were observed between IOM content and tiger fGCM (r = -0.46, p = 0.000), fT3M (r = -0.58, p = 0.000) and lion fT3M measures (r = -0.43, p = 0.003). Two corrective measures viz. removing samples with ≥ 80% IOM and subsequently expressing concentrations as per gram of organic dry matter (instead of total dry matter) reduced IOM influence on tiger fGCM, fT3M and lion fT3M, without affecting lion fGCM measures. The corrective measures changed the interpretations of fT3M data of field-collected tiger samples with no significant changes in fGCM (both tiger and lion) and fT3M (lion) data. As faecal IOM content is common in many wild species, the results emphasize the need to reduce IOM-driven hormone data variation for ecologically relevant interpretations towards species conservation.

Effects of cost surface uncertainty on current density estimates from circuit theory

Background

Conservation practitioners are often interested in developing land use plans that increase landscape connectivity, which is defined as the degree to which the landscape facilitates or impedes movement among resource patches. Landscape connectivity is often estimated with a cost surface that indicates the varying costs experienced by an organism in moving across a landscape. True, or absolute costs are rarely known however, and therefore assigning costs to different landscape elements is often a challenge in creating cost surface maps. As such, we consider it important to understand the sensitivity of connectivity estimates to uncertainty in cost estimates.

Methods

We used simulated landscapes to test the sensitivity of current density estimates from circuit theory to varying relative cost values, fragmentation, and number of cost classes (i.e., thematic resolution). Current density is proportional to the probability of use during a random walk. Using Circuitscape software, we simulated electrical current between pairs of nodes to create current density maps. We then measured the correlation of the current density values across scenarios.

Results

In general, we found that cost values were highly correlated across scenarios with different cost weights (mean correlation ranged from 0.87 to 0.92). Changing the spatial configuration of landscape elements by varying the degree of fragmentation reduced correlation in current density across maps. We also found that correlations were more variable when the range of cost values in a map was high.

Discussion

The low sensitivity of current density estimates to relative cost weights suggests that the measure may be reliable for land use applications even when there is uncertainty about absolute cost values, provided that the user has the costs correctly ranked. This finding should facilitate the use of cost surfaces by conservation practitioners interested in estimating connectivity and planning linkages and corridors.

Insights from distribution dynamics inform strategies to conserve a dhole Cuon alpinus metapopulation in India

Most large carnivore populations currently occur in heterogeneous landscapes, with source populations embedded in a matrix of human-dominated habitats. Understanding changes in distribution of endangered carnivores is critical for prioritizing and implementing conservation strategies. We examined distribution and dynamics of a dhole Cuon alpinus metapopulation, first in 2007 and subsequently in 2015, based on indirect sign surveys across 37, 000sq. km of India's Western Ghats. Predicted dhole occupancy declined from 0.62 (95% CI: 0.58-0.66) in 2007 to 0.54 (95% CI: 0.50-0.58) in 2015. Occupancy was associated with abundance of primary prey species and anthropogenic disturbance. Local extinction appeared to be influenced by forest cover loss, and offset by protected reserves; colonization was influenced by occupancy in neighbouring sites. Perturbation analysis indicated that occupancy was more sensitive to local extinction within reserves and to colonization in sites abutting reserves. The Western Ghats could serve as a stronghold for the endangered dhole, provided future colonizations are facilitated through habitat consolidation beyond reserve boundaries, and local extinctions are prevented by increasing protection efforts within select reserves. We advocate for wildlife managers to adopt a landscape-based approach and periodic monitoring to ensure persistence of the dhole metapopulation in Western Ghats, and in other critical conservation regions across the species' geographic range.

Understanding drivers of human-leopard conflicts in the Indian Himalayan region: Spatio-temporal patterns of conflicts and perception of local communities towards conserving large carnivores

Human killing is the decisive and most critical expression of human-leopard conflict and needs to be addressed sensitively to maintain local support for leopard conservation in India. This research was undertaken to investigate the ecological aspects of human killing and injury, spatial characteristic and pattern of such sites, temporal and seasonal trends of attacks and perception of local communities towards leopard in the Indian Himalayan region (IHR). We surveyed two sites i) Pauri Garhwal in the western part and ii) North Bengal (Dooars) in the eastern part of IHR, compiled secondary data on human-leopard conflict records and made field visits to (N = 101) conflict sites. We also conducted (N = 186) semi-structured questionnaire surveys in each of the sites to assess perception of local communities towards leopard. We analyzed the conflict data using rare events model in a binary logistic regression framework to understand spatial patterns of such incidents for Pauri Garhwal and North Bengal. The average number of injuries and deaths to leopard attacks in Pauri was estimated to be 11 (SE 1.13) and 3 (SE 0.6) per year between 2006-2016 whereas in North Bengal it was estimated to be 70 (SE 9.2) and 1.6 (SE 0.3) respectively between 2004-2016. About 97% of the leopard attacks in North Bengal and 60% of the leopard attacks in Pauri resulted in human injuries. Majority of the leopard attack victims in Pauri were children and young people, whereas in North Bengal it was middle aged tea estate workers. Attack on humans in Pauri were recorded mostly near areas with dense scrub cover whereas in North Bengal it was reported within tea-estates. The percentage of human deaths to leopard attacks in Pauri were higher (40%) compared to a mere (3%) in North Bengal. Forty-one percent of respondents in Pauri and 75% in North Bengal were positive towards presence and conservation of leopard. A predictive risk map revealed central and northern regions of Pauri Garhwal and protected areas, peripheral areas in central and south-western dooars (North Bengal) as high "human-leopard conflict risk zones". This analytical procedure can be adopted in other sites to identify potential human-carnivore conflict risk zones.

Multi-species genetic connectivity in a terrestrial habitat network

BACKGROUND

Habitat fragmentation reduces genetic connectivity for multiple species, yet conservation efforts tend to rely heavily on single-species connectivity estimates to inform land-use planning. Such conservation activities may benefit from multi-species connectivity estimates, which provide a simple and practical means to mitigate the effects of habitat fragmentation for a larger number of species. To test the validity of a multi-species connectivity model, we used neutral microsatellite genetic datasets of Canada lynx (Lynx canadensis), American marten (Martes americana), fisher (Pekania pennanti), and southern flying squirrel (Glaucomys volans) to evaluate multi-species genetic connectivity across Ontario, Canada.

RESULTS

We used linear models to compare node-based estimates of genetic connectivity for each species to point-based estimates of landscape connectivity (current density) derived from circuit theory. To our knowledge, we are the first to evaluate current density as a measure of genetic connectivity. Our results depended on landscape context: habitat amount was more important than current density in explaining multi-species genetic connectivity in the northern part of our study area, where habitat was abundant and fragmentation was low. In the south however, where fragmentation was prevalent, genetic connectivity was correlated with current density. Contrary to our expectations however, locations with a high probability of movement as reflected by high current density were negatively associated with gene flow. Subsequent analyses of circuit theory outputs showed that high current density was also associated with high effective resistance, underscoring that the presence of pinch points is not necessarily indicative of gene flow.

CONCLUSIONS

Overall, our study appears to provide support for the hypothesis that landscape pattern is important when habitat amount is low. We also conclude that while current density is proportional to the probability of movement per unit area, this does not imply increased gene flow, since high current density tends to be a result of neighbouring pixels with high cost of movement (e.g., low habitat amount). In other words, pinch points with high current density appear to constrict gene flow.

When, where and whom: assessing wildlife attacks on people in Chitwan National Park, Nepal

Wildlife attacks on people in and around protected areas have become one of the main challenges for wildlife management authorities. We assessed all correlates of wildlife attacks during 2003–2013 in the vicinity of Chitwan National Park, Nepal. We used data from various sources (discussion with stakeholders, field observations, questionnaire surveys). Wildlife attacks were significantly correlated to factors such as site, season and time, activity, gender and awareness. Moreover, 89% of recorded attacks occurred outside the Park. The number of attacks fluctuated widely and patterns of attacks were significantly uneven across seasons and months. Of the 87% of attacks that occurred during the day, 63% occurred in the morning. Most victims were male and c. 45% of attacks occurred when people were collecting forest resources or working on croplands. Attacks were carried out predominantly by rhinoceros Rhinoceros unicornis (38%), tigers Panthera tigris (21%), sloth bears Melursus ursinus (18%), elephants Elephas maximus (9%) and wild boar Sus scrofa (8%). The people attacked lived close to the Park, depended on farming for their livelihoods, and had little knowledge of animal behaviour. Attacks can be mitigated through proper management of habitats inside the Park and raising awareness of wildlife behaviour among local people. We recommend establishing a participatory emergency rescue team to deal with problematic animals in high-risk areas.