Patterns and Determinants of Habitat Occupancy by the Asian Elephant in the Western Ghats of Karnataka, India

Abstract

Understanding species distribution patterns has direct ramifications for the conservation of endangered species, such as the Asian elephant Elephas maximus. However, reliable assessment of elephant distribution is handicapped by factors such as the large spatial scales of field studies, survey expertise required, the paucity of analytical approaches that explicitly account for confounding observation processes such as imperfect and variable detectability, unequal sampling probability and spatial dependence among animal detections. We addressed these problems by carrying out ‘detection—non-detection’ surveys of elephant signs across a c. 38,000-km2 landscape in the Western Ghats of Karnataka, India. We analyzed the resulting sign encounter data using a recently developed modeling approach that explicitly addresses variable detectability across space and spatially dependent non-closure of occupancy, across sampling replicates. We estimated overall occupancy, a parameter useful to monitoring elephant populations, and examined key ecological and anthropogenic drivers of elephant presence. Our results showed elephants occupied 13,483 km2 (SE = 847 km2) corresponding to 64% of the available 21,167 km2 of elephant habitat in the study landscape, a useful baseline to monitor future changes. Replicate-level detection probability ranged between 0.56 and 0.88, and ignoring it would have underestimated elephant distribution by 2116 km2 or 16%. We found that anthropogenic factors predominated over natural habitat attributes in determining elephant occupancy, underscoring the conservation need to regulate them. Human disturbances affected elephant habitat occupancy as well as site-level detectability. Rainfall is not an important limiting factor in this relatively humid bioclimate. Finally, we discuss cost-effective monitoring of Asian elephant populations and the specific spatial scales at which different population parameters can be estimated. We emphasize the need to model the observation and sampling processes that often obscure the ecological process of interest, in this case relationship between elephants to their habitat.

Predicting range shifts of Asian elephants under global change

“…Human disturbance and land use change have historically been the main drivers of elephant population decline (Choudhury et al, ). Several studies have highlighted the sensitivity of Asian and African elephants to human disturbances (Buij et al, ; Jathanna, Karanth, Kumar, Karanth, & Goswami, ; Srinivasaiah, Anand, Vaidyanathan, & Sinha, ). Our results indicate here that human disturbances represented by the proportion of croplands in a 1.5 × 1.5 km area exerted negative influence on elephant occurrence patterns (Figure ).…”

“…The loss of habitat is projected to occur mostly in the human‐dominated regions, that is, the Central‐Eastern (Eastern Ghats) and the Southern Western Ghats of India and in the relatively flat areas of the Himalayan region (Figure a,b). Loss of native forests (Puyravaud, Davidar, & Laurance, ) and land degradation, which affects about 18% of its territory (Bai, Dent, Olsson, & Schaepman, ), are major threats to India's biodiversity that will decrease the availability of forage for wild herbivores (Jathanna et al, ; Madhusudan, ). Climate change will further amplify these threats leading to species declines and eventual extinction (Thomas et al, ).…”

Peer Review #2 of "Habitat suitability and connectivity inform a co-management policy of protected area network for Asian elephants in China (v0.2)"

“…Asian elephants frequently occur in areas of low altitude, flat terrain, and low human disturbance and feed on natural foods or crops near forest edge (Jathanna et al, 2015, Liu et al, 2016. Hence, we selected thirteen environmental variables in three categories for habitat suitability models (Table 1): i.e., geographic and topographic (altitude and terrain roughness index), land-cover (distance to, edge density of, and percentage of natural forest, pine plantation, and traditional farmland), and human disturbance (distance to town and distance to community).…”

“…Large animals are particularly affected because of their wide range (Ceballos & Ehrlich, 2002;Robert et al, 2006) and negative interactions with villagers (Acharya et al, 2017, AsERSM, 2017. Although Asian elephants (Elephas maximus) are endangered species and are important in ecosystem function (e.g., seed dispersal and nutrient recycling), culture, and fundraising for wildlife conservation (Campos-Arceiz et al, 2008;Ritchie & Johnson, 2009;Verissimo et al, 2011), only 29% of their distribution range is legally protected in 13 countries (Hedges et al, 2008), and most is in human-dominated landscapes (Jathanna et al, 2015, Calabrese et al, 2017. Enlarging PAN was suggested as a priority for their conservation (AsERSM, 2017).…”

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“…Asian elephant (Elephas maximus) is an endangered, flagship, and umbrella species in South and Southeast Asia. Despite their importance in ecosystem, culture, as well as fundraise for broader wildlife conservation (Campos-Arceiz et al, 2008;Ritchie & Johnson, 2009;Verissimo et al, 2011), only 29.1% of their distribution range was legally protected in thirteen countries (Hedges et al, 2008), most of them persist in human-dominated landscapes (Calabrese et al, 2017;Jathanna et al, 2015). Enlarging PAs network is a priority for their long-term viability (AsERSM, 2017).…”