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Browsing by Author "Dhakal, Maheshwar"

Now showing 1 - 3 of 3
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    Assessment of genetic diversity, population structure, and gene flow of tigers (Panthera tigris tigris) across Nepal's Terai Arc Landscape
    Thapa, Kanchan; Manandhar, Sulochana; Bista, Manisha; Shakya, Jivan; Sah, Govind; Dhakal, Maheshwar; Sharma, Netra; Llewellyn, Bronwyn; Wultsch, Claudia; Waits, Lisette P.; Kelly, Marcella J.; Hero, Jean-Marc; Hughes, Jane; Karmacharya, Dibesh (PLOS, 2018-03-21)
    With fewer than 200 tigers (Panthera tigris tigris) left in Nepal, that are generally confined to five protected areas across the Terai Arc Landscape, genetic studies are needed to provide crucial information on diversity and connectivity for devising an effective country-wide tiger conservation strategy. As part of the Nepal Tiger Genome Project, we studied landscape change, genetic variation, population structure, and gene flow of tigers across the Terai Arc Landscape by conducting Nepal's first comprehensive and systematic scat-based, non-invasive genetic survey. Of the 770 scat samples collected opportunistically from five protected areas and six presumed corridors, 412 were tiger (57%). Out of ten microsatellite loci, we retain eight markers that were used in identifying 78 individual tigers. We used this data set to examine population structure, genetic variation, contemporary gene flow, and potential population bottlenecks of tigers in Nepal. We detected three genetic clusters consistent with three demographic sub-populations and found moderate levels of genetic variation (H-e = 0.61, A(R) = 3.51) and genetic differentiation (F-ST = 0.14) across the landscape. We detected 3-7 migrants, confirming the potential for dispersal-mediated gene flow across the landscape. We found evidence of a bottleneck signature likely caused by large-scale land-use change documented in the last two centuries in the Terai forest. Securing tiger habitat including functional forest corridors is essential to enhance gene flow across the landscape and ensure long-term tiger survival. This requires cooperation among multiple stakeholders and careful conservation planning to prevent detrimental effects of anthropogenic activities on tigers.
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    Leopard Panthera pardus fusca Density in the Seasonally Dry, Subtropical Forest in the Bhabhar of Terai Arc, Nepal
    Thapa, Kanchan; Shrestha, Rinjan; Karki, Jhamak; Thapa, Gokarna Jung; Subedi, Naresh; Pradhan, Narendra Man Babu; Dhakal, Maheshwar; Khanal, Pradeep; Kelly, Marcella J. (Hindawi, 2014-07-16)
    We estimated leopard (Panthera pardus fusca) abundance and density in the Bhabhar physiographic region in Parsa Wildlife Reserve, Nepal. The camera trap grid, covering sampling area of 289 km2 with 88 locations, accumulated 1,342 trap nights in 64 days in the winter season of 2008-2009 and photographed 19 individual leopards. Using models incorporating heterogeneity, we estimated 28 (±SE 6.07) and 29.58 (±SE 10.44) leopards in Programs CAPTURE and MARK. Density estimates via 1/2 MMDM methods were 5.61 (±SE 1.30) and 5.93 (±SE 2.15) leopards per 100 km2 using abundance estimates from CAPTURE and MARK, respectively. Spatially explicit capture recapture (SECR) models resulted in lower density estimates, 3.78 (±SE 0.85) and 3.48 (±SE 0.83) leopards per 100 km2, in likelihood based program DENSITY and Bayesian based program SPACECAP, respectively. The 1/2 MMDM methods have been known to provide much higher density estimates than SECR modelling techniques. However, our SECR models resulted in high leopard density comparable to areas considered better habitat in Nepal indicating a potentially dense population compared to other sites. We provide the first density estimates for leopards in the Bhabhar and a baseline for long term population monitoring of leopards in Parsa Wildlife Reserve and across the Terai Arc.
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    On the tiger trails: Leopard occupancy decline and leopard interaction with tigers in the forested habitat across the Terai Arc Landscape of Nepal
    Thapa, Kanchan; Malla, Sabita; Subba, Samundra Ambuhang; Thapa, Gokarna Jung; Lamichhane, Babu Ram; Subedi, Naresh; Dhakal, Maheshwar; Acharya, Krishna Prasad; Thapa, Madhuri Karki; Neupane, Pramod; Poudel, Shashank; Bhatta, Shiv Raj; Jnawali, Shant Raj; Kelly, Marcella J. (2021-01)
    Better conservation planning requires updated information about leopard distribution to prioritize and allocate limited resources available. The long-term persistence of leopards and sympatric tigers can be compromised by linear infrastructure development such as roads that fragment habitat. We used detection and non-detection data collected along walking search paths (similar to 4140 km) in 96 grid cells (each cell 15 km by 15 km) spread across potential habitat (similar to 13,845 km(2)) in the Terai Arc Landscape, Nepal. Multi-season occupancy models allowed us to make both spatial and temporal inferences between two surveys in 2009 and 2013, based on ecologically relevant covariates recorded in the field or remotely sensed. Additionally, we used 2013 data to make inferences on co-occurrence between tigers and leopards at the landscape level. We found the additive model containing deforestation and district roads negatively influenced leopard detection across the landscape. Although weak, we found anthropogenic factors such as extent of deforestation (decrease in forest cover) negatively affected leopard occupancy. Road abundance, especially for the east-west highway and district roads, also negatively (but weakly) influenced leopard occupancy. We found substantially lower occupancy in the year 2013 (0.59 (SE 0.06)) than in 2009 (0.86 (SE 0.04)). Tigers and leopards co-occurred across the landscape based on the species interaction factor (SIF) estimated at 1.47 (0.13) but the amount of available habitat and the prey index mediated co-occurrence. The SIF decreased as habitat availability increased, reaching independence at large habitat patches, but leopard occupancy declined in sites with tigers, primarily in large patches. The prey index was substantially lower outside of protected areas and leopards and tigers co-occurred more strongly in small patches and at low prey indices, indicating potential attraction to the same areas when prey is scarce. Mitigation measures should focus on preventing loss of critical leopard, tiger, and prey habitat through appropriate wildlife-friendly underpasses and avoiding such habitat when building infrastructure. Leopard conservation has received lower priority than tigers, but our metrics show a large decline in leopard occupancy, thus conservation planning to reverse this decline should focus on measures to facilitate human-leopard coexistence to ensure leopard persistence across the landscape.