Large mammals in the Western Ghats
A wide array of large mammals, including some that are globally rare and endangered, inhabit the Western Ghats. Yet, we do not know how they are distributed across this landscape today, or how their ranges here have changed over time. It is this gap in our knowledge that this project tries to address.
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- Journal Article2014Accounting for false positives improves estimates of occupancy from key informant interviewsDiversity and Distributions 20: 223-235Download
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Much research in conservation biogeography is fundamentally dependent on obtaining reliable data on species distributions across space and time. Such data are now increasingly being generated using various types of public surveys. These data are often integrated with occupancy models to evaluate distributional patterns, range dynamics and conservation status of multiple species at broad spatio-temporal scales. Occupancy models have traditionally corrected for imperfect detection due to false negatives while implicitly assuming that false positives do not occur. However, public survey data are also prone to false-positive errors, which when unaccounted for can cause bias in occupancy estimates. We test whether false positives in a dataset collected from public surveys lead to overestimation of species site occupancy and whether estimators that simultaneously account for false-positive and false-negative errors improve occupancy estimates.
Western Ghats, India.
We fit occupancy models that simultaneously account for false positives and negatives to data collected from a large-scale key informant interview survey for 30 species of large vertebrates. We tested their performance against standard occupancy models that account only for false negatives.
Standard occupancy models that correct only for false negatives tended to overestimate species occupancy due to false-positive errors. Occupancy models that simultaneously accounted for false positives and negatives had greater support [lower Akaike's information criterion (AIC)] and, consistent with predictions, generated systematically lower occupancy estimates than standard models. Furthermore, accounting for false positives improved the accuracy of occupancy estimates despite the added complexity to the statistical estimator.
Integrating large-scale public surveys with occupancy modelling approaches is a powerful tool for informing conservation and management. However, in many if not most cases, it will be important to explicitly account for false positives to ensure the reliability of occupancy estimates obtained from public survey datasets such as key informant interviews, volunteer surveys, citizen science programmes, historical archives and acoustic surveys.
- Popular Article2012A problem landscape in the Western GhatsHornbill, April-June, 2012 : 4-8
- Journal Article2011Patterns of spatiotemporal change in large mammal distribution and abundance in the southern Western Ghats, IndiaBiological Conservation 144: 1567-1576Download
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Large mammals face high risks of anthropogenic extinction owing to their larger body mass and associated life history traits. Recent worldwide mammal declines have highlighted the conservation importance of effective assessments of trends in distribution and abundance of species. Yet reliable data depicting the nature and extent of changes in population parameters is sparse, primarily due to logistical problems in covering large areas and difficulties in obtaining reliable information at large spatial scales, particularly over time. We used key informant surveys to generate detection histories for 18 species of large mammals (body mass > 2 kg) at two points in time (present and 30 years ago) in the Southern subregion of the Western Ghats global biodiversity hotspot. Multiple-season occupancy models were used to assess temporal trends in occupancy, detectability and vital rates of extinction and colonization for each species. Our results show significant declines in distribution for large carnivores, the Asian elephant and endemic ungulates and primates. There is a significant decline in detectability for 16 species, which suggests a decline in their abundance. These patterns of change in distribution and abundance repeat in our assessments of spatial variation in occupancy dynamics between the three contiguous forest complexes and two human-dominated landscapes into which the southern Western Ghats has been fragmented. Extinction rates are highest in the human-dominated landscapes. Declines in abundance for several species suggest the presence of extinction debts, which may soon be repaid with imminent range contractions and subsequent species extinctions unless immediate remedial conservation measures are taken. Detection/non-detection surveys of key informants used in an occupancy modeling framework provide potential for rapid conservation status assessments of multiple species across large spatial scales over time.
- Popular Article2010Lure of the wildFrontline 27(5): 64-73
- Journal Article2010Ensuring the future of the tiger and other large mammals in the southern portion of the Nilgiri Biosphere Reserve, southern IndiaJournal of the Bombay Natural History Society 107: 77-85Download
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The Nilgiri Biosphere Reserve, at the tri-junction of Tamil Nadu, Kerala and Karnataka, constitutes arguably one of the finest conservation landscapes in the global range of the tiger. We surveyed the southern part of this region, as well as the adjoining areas, to assess the status of large mammals both within and outside protected areas. Our field assessments suggest that large mammals are almost exclusively confined to protected areas with the few remaining populations outside under severe threat from habitat degradation and poaching. However, large stretches of contiguous forests still remain. We suggest the extension of the recently notified Mudumalai Tiger Reserve in Tamil Nadu such that connectivity is retained and strengthened with Biligiri Rangaswamy Temple Wildlife Sanctuary of Karnataka to the north-east and with Silent Valley National Park of Kerala to the south. We also provide suggestions on strengthening conservation in this landscape. The involvement of local communities in the establishment of the Siruvani Conservation Reserve in Kerala and Tamil Nadu, and Nilambur Conservation Reserve in Kerala, will bolster the conservation of large mammals in this landscape. With the suggested extension, Mudumalai Tiger Reserve has the potential of becoming arguably the finest habitat for tigers across Asia, given the variations in altitude, topography and climate which produce a diversity of vegetation types and consequently, provide the tiger with an assortment of prey ranging from Nilgiri Tahr in the high altitude montane grasslands to Blackbuck in the low-lying dry deciduous and thorn scrub forests.
- Popular Article2010Saving SahyadriFrontline 27(24):64-72Download
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Tigers are on the retreat from the Sahyadris and the predator’s preferred prey, the sambar, is on the decline.
- Popular Article2010The Mukurthy-Mudumalai Large Mammal CorridorSanctuary Asia, Oct 2010 : 72-73
- Popular Article2010Cry in the WildernessFrontline 26(26): 64-74
Many conservation issues need to be addressed to ensure the future of the wildlife in the Cauvery forests.
- Popular Article2009Mountain rainforests. Quest for large mammals in the southern Western GhatsSanctuary Asia 29 (April): 48-53Download
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The jeeps forming a crescent beside the forest stream switched on their headlights almost simultaneously, brightly illuminating
the drama unfolding before my eyes. Fifteen wild elephants were approaching the water from the forest beyond, unfazed by the presence of a horde of humans less than 20 m away. I was in Anakulam, a remote village in the rainforests near Eravikulam National Park in Kerala. During a field survey in the southern
Western Ghats, reports had filtered through of a fabled spot where elephants have been congregating since living memory to drink at a natural mineral spring. To ascertain the veracity of these stories, the Nature Conservation Foundation (NCF) team, led by Dr. A.J.T. Johnsingh, braved the rough, mountainous roads to Anakulam (meaning ‘elephant pond’) through dense Ochlandra reed brakes, arriving at dusk, only to find the locals playing cricket beside the stream!
- Conference Proceedings2009Opportunities and challenges for tiger (Panthera tigris) conservation in the southern Western Ghats, IndiaShifting Trajectories of Ecology and Coexistence: Proceedings of the National Seminar on People and Tigers. Kerala Forest Department, Periyar Tiger Reserve, Thekkady, India. pp. 135-147Download
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The southern Western Ghats is an important ecological subunit of the Western Ghats biodiversity hotspot. Dominated by moist forests, including tropical wet evergreen forests, it has higher levels of biodiversity and endemism than the rest of the Western Ghats. There are 19 Protected Areas in the southern Western Ghats that cover 36% of its total area, among which Parambikulam, Anamalai and Periyar Tiger Reserves stand out as primary source habitats for tigers. The region is fragmented from north to south into the Anamalai, Periyar and Agasthyamalai landscapes. Given the crucial need for large, contiguous areas to ensure the persistence of wide-ranging large predators such as the tiger Panthera tigris and its prey, it is important to establish and maintain habitat connectivity within and between these landscapes, whereas conservation efforts today are focused on small, insular protected areas. Possibilities for forging connectivity between the Anamalai and Periyar landscapes along Kerala state are nonexistent owing to the loss of Devikulam Range in Munnar Forest Division to cardamom cultivation and developments related to tourism and Kumily Range in Kottayam Forest Division to encroachment. The link on the Tamil Nadu side, along the steep eastern slopes of Theni Forest Division, is extremely narrow and consequently unsuitable for large mammal movement at present. Our surveys, however, point to the possibility of bridging this gap through a corridor at Kottavasal. Recent camera-trapping studies by the Wildlife Institute of India, Dehradun have highlighted the precarious situation of tigers in Kalakad-Mundanthurai Tiger Reserve in the Agasthyamalai landscape. Therefore, establishment of the Kottavasal corridor and the Kulathupuzha Conservation Reserve is a must to secure the future of tiger in the Agasthyamalai landscape. It is important that all endeavours now be made to enable the Anamalai and Periyar-Agasthyamalai landscapes to each sustain a minimum population of 100 adult tigers. Controlling poaching of prey species especially sambar Cervus unicolor, establishment of protected areas such as Kodaikanal, Megamalai and Kulathupuzha, acquisition of failed private estates to facilitate large mammal recolonization and restoration of native vegetation in exotic species plantations are priority tasks that need immediate attention in order to realize the huge opportunities for tiger conservation in the southern Western Ghats.