- Popular Article2013A morning with ‘Bloated Stomach’The Hindu in School, 8 May
- Popular Article2013Not so deserted, after all!The Hindu in School, 6 November
- Journal Article2013Design and Evaluation of a Robust Optical Beam-Interruption-Based Vehicle Classiﬁer SystemIEEE Transactions on Intelligent Transportation Systems 14(3): 1043-1052Download
PDF, 833 KB
This paper presents the design and development of a novel optical vehicle classifier system, which is based on interruption of laser beams, that is suitable for use in places with poor transportation infrastructure. The system can estimate the speed, axle count, wheelbase, tire diameter, and the lane of motion of a vehicle. The design of the system eliminates the need for careful optical alignment, whereas the proposed estimation strategies render the estimates insensitive to angular mounting errors and to unevenness of the road. Strategies to estimate vehicular parameters are described along with the optimization of the geometry of the system to minimize estimation errors due to quantization. The system is subsequently fabricated, and the proposed features of the system are experimentally demonstrated. The relative errors in the estimation of velocity and tire diameter are shown to be within 0.5% and to change by less than 17% for angular mounting errors up to 30°. In the field, the classifier demonstrates accuracy better than 97.5% and 94%, respectively, in the estimation of the wheelbase and lane of motion and can classify vehicles with an average accuracy of over 89.5%.
- Journal Article2013Role of Tibetan Buddhist Monasteries in Snow Leopard ConservationConservation Biology. DOI: 10.1111/cobi.12135
- Journal Article2013Globalization of the Cashmere Market and the Decline of Large Mammals in Central AsiaConservation Biology 27: 679-689
- Journal Article2013Large carnivores and low diversity of optimal prey: a comparison of the diets of snow leopards Panthera uncia and wolves Canis lupus in Sarychat-Ertash Reserve in KyrgyzstanOryx DOI:10.1017/S0030605313000306
- Popular Article2013Securing Habitat of NemoFriday, April 12, Andaman Chronicles.
- Journal Article2013Reversible immobilization of free-ranging snow leopards (Panthera uncia) using a combination of Medetomidine and Tiletamine-ZolazepamJournal of Wildlife Diseases DOI: 10.7589/2012-02-049
- Journal Article2013An expedition to Narcondam: observations of marine and terrestrial fauna including the island-endemic hornbill.Current Science 105: 346-360.
- Popular Article2013A day in the life of a butterfly fishThe Hindu in School, 10 July
- Popular Article2013Acrobats on waterThe Hindu in School, 13 February
Jeganathan, P. (2013). Acrobats on water. The Hindu. In school, 13th February.
- Journal Article2013Green turtle herbivory dominates the fate of seagrass primary production in the Lakshadweep islands (Indian Ocean)Marine Ecology Progress Series. 485:235-243
Historical global declines of megaherbivores from marine ecosystems have hitherto contributed to an understanding of seagrass meadow production dominated by detrital path- ways — a paradigm increasingly being questioned by recent re-evaluations of the importance of herbivory. Recoveries in green turtle populations at some locations provide an ideal opportunity to examine effects of high megaherbivore densities on the fate of seagrass production. We conducted direct field measurements of aboveground herbivory and shoot elongation rates in 9 seagrass meadows across 3 atolls in the Lakshadweep Archipelago (India) representing a gradient of green turtle densities. Across all meadows, green turtles consumed an average of 60% of the total leaf growth. As expected, herbivory rates were positively related to turtle density and ranged from being almost absent in meadows with few turtles, to potentially overgrazed meadows (ca. 170% of leaf growth) where turtles were abundant. Turtle herbivory also substantially reduced shoot elongation rates. Simulated grazing through clipping experiments confirmed this trend: growth rates rapidly declined to almost half in clipped plots relative to control plots. At green turtle den- sities similar to historical estimates, herbivory not only dominated the fate of seagrass primary pro- duction but also drastically reduced production rates in grazed meadows. Intensive turtle grazing and associated movement could also modify rates of detrital cycling, leaf export and local carbon burial, with important consequences for the entire seascape.
- Book Chapter2013Anthropogenic Influences on Macaque Populations and Their Genetic ConsequencesPages 209 to 224 in S. Radhakrisna and A. Sinha (editors) The Macaque Connection: Cooperation and Conflict between Humans and Macaques, Springer, New Delhi.Download
PDF, 338 KB
Human–macaque interactions constitute a complex phenomenon influencing perhaps the biology of the macaque more profoundly than ours. At the population level, humans tend to influence the distribution, demography, immunology and even behaviour of the macaque species they interact with though none of these interactions are ever simple. These works at different levels, interacting, in turn, with other environmental factors and most of these impacts are likely to have genetic consequences over the long term. In this chapter, we reviewed available literature on anthropogenic impacts on macaque populations. We should, however, stress that our current state of knowledge, unfortunately, suffers from a serious lack of insight into such genetic impacts. There is, therefore, a dire need for long-term genetic monitoring programmes to understand the effect of anthropogenic factors on the dispersal and demography of different macaque species.
- Popular Article2012சின்னஞ்சிறுகுருவே…(On Ants)புதிய தலைமுறை. 26ஜூலை 2012. Puthiya Thalaimurai. 26th July 2012.
- Journal Article2012Methodological, temporal and spatial factors affecting modelled occupancy of resident birds in the perennially cultivated landscape of Uttar Pradesh, IndiaLandscape Ecology 27: 59-71. doi:10.1007/s10980-011-9666-3.
Biodiversity persistence in non-woody tropical farmlands is poorly explored, and multispecies assessments with robust landscape-scale designs are sparse. Modeled species occupancy in agricultural mosaics is affected by multiple factors including survey methods (convenience-based versus systematic), landscape-scale agriculture-related variables, and extent of remnant habitat. Changes in seasonal crops can additionally alter landscape and habitat conditions thereby influencing species occupancy. We investigated how these factors affect modeled occupancy of 56 resident bird species using a landscape-scale multi-season occupancy framework across 24 intensively cultivated and human-dominated districts in Uttar Pradesh state, north India. Convenience-based roadside observations provided considerable differences in occupancy estimates and associations with remnant habitat and intensity of cultivation relative to systematic transect counts, and appeared to bias results to roadside conditions. Modeled occupancy of only open-area species improved with increasing intensity of cultivation, while remnant habitat improved modeled occupancy of scrubland, wetland and woodland species. Strong seasonal differences in occupancy were apparent for most species across all habitat guilds. Further habitat loss will be most detrimental to resident scrubland, wetland and woodland species. Uttar Pradesh’s agricultural landscape has a high conservation value, but will require a landscape-level approach to maintain the observed high species richness. Obtaining ecological information from unexplored landscapes using robust landscape-scale surveys offers substantial advantages to understand factors affecting species occupancy, and is necessary for efficient conservation planning.
- Journal Article2012Impact of vehicular traffic on large mammal use of highway-edges in southern IndiaCurrent Science 102(7): 1047-1051Download
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India’s phenomenal economic growth over the last decade has been accompanied by a much-needed expansion and improvement in transport and other infrastructure networks. While there are legally mandated assessments of the potential ecological impacts of such infrastructure projects prior to implementation, rarely are there post-implementation assessments of their real ecological impacts. In this communication, we present results of a preliminary study examining the impact of vehicular traffic on the usage of road edges by large mammals along a highway passing through Nagarahole Tiger Reserve, southern India. We estimated large mammal encounter rates at remotely triggered camera traps on two consecutive sections of the same highway – one closed to vehicular traffic and the other open to vehicles only during daytime. We observed lower encounter rates of chital, gaur and elephants at camera traps in the highway segment with higher vehicular traffic density, suggesting that these species avoided busy highways. Based on our findings, we emphasize the importance of continued ecological impact assessments of development projects to identify and mitigate unforeseen impacts. Further, an approach to development planning that integrates conservation concerns, especially where development projects coincide with ecologically critical areas, is urgently needed in India.
- Journal Article2012Optimizing individual identification and survey effort for photographic capture–recapture sampling of species with temporally variable morphological traitsAnimal Conservation 15(2): 174-183
Endangered, wide-ranging megafauna have many threats to contend with during their struggle for survival in an ever-increasing human dominance of the environment. Reliable monitoring of endangered large mammal populations is therefore a critical conservation requirement. Photographic capture–recapture (CR) techniques have opened up avenues for population monitoring of individually recognizable large mammal species. The efficient application of these techniques, however, can be constrained by challenges in reliably identifying individuals arising from the use of multiple, and potentially variable traits, as well as issues of temporal sampling of populations in the field. We address these key problems by describing an automated process of rapidly identifying individual Asian elephants (Elephas maximus) from photographs, and comparing resultant CR-based population parameter estimates with those obtained using supervised visual identification of individuals. In addition, we assess the temporal effort necessary for robust estimation of demographic parameters in our study population. Morphological traits that maintain constancy over time, including variations in tusk characteristics, and ear fold and lobe shape, proved the most reliable for individual identification and subsequent estimation of population parameters. The use of temporally variable traits contributed to high probabilities of misidentification and biased estimates of population size. We found a minimum of seven sampling occasions necessary for reliable population estimation. Our study contributes to design issues for CR studies by providing insights into optimality of sampling effort such that precision of parameter estimates are not compromised while minimizing survey costs. We demonstrate the importance of accurate individual identification in the context of such studies and recommend the use of fixed morphological traits as the optimal individual identification strategy for species where animals are distinguished on the basis of multiple attributes, including some that may be variable over time.
- Journal Article2012Streamside amphibian communities in plantations and a rainforest fragment in the Anamalai hills, IndiaJournal of Threatened Taxa 4: 2849–2856.Download
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Stream amphibian communities, occupying a sensitive environment, are often useful indicators of effects of adjoining land uses. We compared abundance and community composition of anuran amphibians along streams in tea monoculture, shade coffee plantation, and a rainforest fragment in Old Valparai area of the Anamalai hills. Overall species density and rarefaction species richness was the highest in rainforest fragment and did not vary between the coffee and tea land uses. Densities of certain taxa, and consequently community composition, varied significantly among the land uses, being greater between rainforest fragment and tea monoculture with shade coffee being intermediate. Observed changes are probably related to streamside alteration due to land use, suggesting the need to retain shade tree cover and remnant riparian rainforest vegetation as buffers along streams.
- Popular Article2012காட்டு நீரோடையின் மெல்லிசை மன்னன். (On Malabar Whistling Thrush)புதிய தலைமுறை. 2ஆகஸ்டு 2012 Puthiya Thalaimurai. 2nd August 2012
- Popular Article2012புலியா?பறவையா?எதுஉசத்தி? (An article on another article written by Madhusudan Katti on Warbler vs Tigers)புதிய தலைமுறை. 9ஆகஸ்டு 2012. Puthiya Thalaimurai. 9th August 2012.
புலியா? பறவையா? எதுஉசத்தி?. காக்கைக்குருவிஎங்கள்ஜாதிதொடர்-5. புதியதலைமுறை. 9ஆகஸ்டு 2012. [Jeganathan, P. (2012).Puliya? Paravaiya? Ethu Usathi?. Kakkai Kuruvi Engal Jathi-Series, Article No.5 Puthiya Thalaimurai. 9th August 2012. (An article on another article written by Madhusudan Katti on Warbler vs Tigers)]