Abstract
Asiatic lions (Panthera leo persica) are an icon of conservation success, yet their status is inferred from total counts that cannot account for detection bias and double counts. With an effort of 4,797 km in 725 km2 of western Gir Protected Area, India, we used polygon search based spatially explicit capture recapture framework to estimate lion density. Using vibrissae patterns and permanent body marks we identified 67 lions from 368 lion sightings. We conducted distance sampling on 35 transects with an effort of 101.5 km to estimate spatial prey density using generalized additive modeling (GAM). Subsequently, we modeled lion spatial density with prey, habitat characteristics, anthropogenic factors and distance to baiting sites. Lion density (>1-year-old lions) was estimated at 8.53 (SE 1.05) /100 km2 with lionesses having smaller movement parameter (σ = 2.55 km; SE 0.12) compared to males (σ = 5.32 km; SE 0.33). Detection corrected sex ratio (female:male lions) was 1.14 (SE 0.02). Chital (Axis axis) was the most abundant ungulate with a density of 63.29 (SE 10.14) as determined by conventional distance sampling (CDS) and 58.17 (SE 22.17)/km2 with density surface modeling (DSM), followed by sambar (Rusa unicolor) at 3.84 (SE 1.07) and 4.73 (SE 1.48)/km2 estimated by CDS and DSM respectively. Spatial lion density was best explained by proximity to baiting sites and flat valley habitat but not as much by prey density. We demonstrate a scientifically robust approach to estimate lion abundance, that due to its spatial context, can be useful for management of habitat and human-lion interface. We recommend this method for lion population assessment across their range. High lion densities in western Gir were correlated with baiting. The management practice of attracting lions for tourism can perturb natural lion densities, disrupt behavior, lion social dynamics and have detrimental effects on local prey densities.
Highlights
Conservation management of any endangered species depends on information of its population extent, abundance, and current threats [1]
Our results show that current management practices, catering towards reducing conflict and enhancing lion viewing for tourism by baiting them had profound effect on lion spatial density and artificially inflated local densities
Gir Protected Area (PA) extending over an area of 1,883 km2 from 21 ̊ 20’ N to 20 ̊ 57’ N latitude to 70 ̊ 27’ E 71 ̊ 13’ E longitude [30]; (Fig 1) is a dry deciduous forest [31] situated in Gujarat province, western India and is made up of a Sanctuary covering 1,153 km2, a 259 km2 National Park and 471 km2 of additional reserve, protected and unclassified forests [32] (Fig 1)
Summary
Conservation management of any endangered species depends on information of its population extent, abundance, and current threats [1]. Monitoring large carnivore populations with robust scientific methodology is essential because of their. Spatial density of lion and their prey umbrella status [5], their charismatic persona that intrigues societies and political interest [6], and in many cases their endangered nature that requires unbiased estimates [7] for resource allocation and conservation management [8]. Inappropriate monitoring methodology can result in biased estimates that subsequently lead to incorrect policy and management decisions that may be counterproductive for conservation [9]. Use of robust methods that provide unbiased and precise estimates to underpin correct management and policy decisions are an essential part of applied ecology [10]
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