- Journal Article2013An expedition to Narcondam: observations of marine and terrestrial fauna including the island-endemic hornbill.Current Science 105: 346-360.
- Popular Article2013Fungi forayThe Hindu, Young World, 29th January 2013.
Jeganathan, P. (2013). Fungi foray. The Hindu, Young World, 29th January 2013. http://www.thehindu.com/life-and-style/kids/fungi-foray/article4353151.ece
- Journal Article2013Can wetlands maintained for human use also help conserve biodiversity? Landscape–scale patterns of bird use of wetlands in an agricultural landscape in north IndiaBiological Conservation 168: 49-56. http://dx.doi.org/10.1016/j.biocon.2013.09.016
Wetlands in tropical agricultural landscapes are maintained largely by local institutions explicitly for human use, which is assumed to deter biodiversity. Conservation efforts have been biased towards protecting large wetlands that are assumed to be adequate to conserve the majority of species of focal taxa, usually birds. These assumptions remain untested, and landscape-scale conservation planning for wetlands is largely absent, as is a generalised understanding of wetland use by focal taxa. We designed a landscape-scale survey to understand patterns and processes determining beta diversity of birds using agricultural wetlands in south-western Uttar Pradesh, India where wetlands have experienced prolonged and intensive human use for several centuries. Observed bird species richness (99 species in 28 wetlands) is the highest known for any agricultural landscape in south Asia signifying that even intensive human use of wetlands does not necessarily deter their ability to retain biodiversity. Birds exhibited strong scale
dependent wetland use underscoring the need to conserve wetlands of varying sizes and at varying densities on the landscape. Beta diversity was due largely to species turnover (0.877) with minimal effect due to nestedness (0.055) suggesting that conserving a few large wetlands will not adequately meet goals of conserving the majority of wetland bird species. Prevailing assumptions regarding biodiversity conservation in tropical agricultural wetlands require being revised, and a landscape-scale approach that incorporates ecological realities is needed. Incorporating local institutions alongside formal protectionist methods offer a potential win–win situation to maximise conservation of biodiversity in tropical agricultural wetlands.
- Report2013MigrantWatch 2007-2012Unpublished report, Citizen Science Programme, National Centre for Biological Sciences.
- 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.
- Popular Article2013Careful while you clickThe Hindu in School, 18 September
Jeganathan, P. (2013). Careful while you click. The Hindu in School, 18 September.
- Book Review2013Chronicles of the wild -Book review of “Mammals of South Asia by A.J.T. Johnsingh & Nima Manjrekar”.The Asian Age. 23rd February.Download
PDF, 184 KB
Jeganathan, P. (2013). Chronicles of the wild - Book review of “Mammals of South Asia by A.J.T. Johnsingh & Nima Manjrekar”. The Asian Age. 23rd February.
- Popular Article2013Acrobats on waterThe Hindu in School, 13 February
Jeganathan, P. (2013). Acrobats on water. The Hindu. In school, 13th February.
- Popular Article2013மயில் வதை – தடுக்க என்ன வழி? (On Peafowl-human conflict and its mitigation measures)தினமணி நாளிதழ் – கொண்டாட்டம் இணைப்பில். 6 ஜனவரி 2013. Dinamani – Tamil Newspaper. 6th January 2013.
மயில் வதை – தடுக்க என்ன வழி?தினமணி நாளிதழ் – கொண்டாட்டம் இணைப்பில். 6 ஜனவரி 2013.[Jeganathan, P. (2013). Mayil Vathai – Thadukka enna vazi? (On Peafowl-human conflict and its mitigation measures).]
- Popular Article2013ஊசிவால் குளவிகள். (On Ichneumon wasps)தி ஹிந்து தீபாவளி மலர் The Hindu Tamil, Deepavali Malar (Deepavali Special Issue)
- Journal Article2013Complex ecological pathways underlie perceptions of conflict between green turtles and fishers in the Lakshadweep Islands.Biological Conservation 167: 25-34
Managing human–wildlife conflict is often complicated by apparent mismatches between community perceptions and measures of directly incurred losses. Fishers in Agatti Island (Lakshadweep, India) associate recent increases in green turtle (Chelonia mydas) populations with declining fish catches, resulting in targeted killing of turtles. We compared fisher perceptions in Agatti with a very similar atoll, Kadmat, with much lower turtle densities. Nearly 90% of Agatti fishers interviewed blamed turtles for declining catch compared with 20% in Kadmat and proposed two mechanisms for this decline: direct interference (e.g., turtles damaged gear) which we define as first order conflict, and indirect mechanisms (second order conflict): turtles overgrazed seagrasses, thereby reducing fish catch. We evaluated the magnitude of gear loss with interviews and tested proposed indirect mechanisms with a turtle density gradient, before–after comparisons (taking advantage of an increase in turtles in Kadmat and concurrent decrease in Agatti) and a natural herbivore exclosure. These complementary approaches supported fisher-pro- posed second-order mechanisms: at high densities, turtles heavily grazed seagrasses, significantly reduced canopy heights, lowered fish recruit abundance, food fish biomass and catch. Estimates of losses incurred in Agatti show that first-order conflict cost fishers USD 0.6 fisher-1 year1, while second-order pathways accounted for USD 887 fisher-1 year-1. Our results show that local perceptions are fueled by often-complex mechanisms that, though not always straightforward to measure, are very important in generating conflict. Reconciling the human–wildlife interface requires an adequate accounting of direct and indirect mechanisms to more completely reflect true losses communities bear for living with wildlife.
- Journal Article2013Greener pastures? High-density feeding aggregations of green turtles precipitate species shifts in seagrass meadowsJournal of Ecology. 101: 1158-1168
1. Historical declines of marine megaherbivores have led to a view of seagrass communities structured largely by abiotic disturbance and plant competition. There is, however, growing recognition of the significance of top-down control through herbivory, on seagrass ecosystem processes, raising the question of how meadows functioned under historically high populations of megaherbivores. 2. We assess the impacts of such intense herbivory on seagrass meadow composition in the Lakshadweep islands (India), where high-density feeding aggregations of green turtles have persisted for over a decade. We use a series of complementary approaches: (i) natural herbivory exclosures (ii) published data on seagrass composition before and after turtles established (at one atoll: Agatti) and (iii) present species composition along a turtle herbivory gradient over multiple atolls.
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- Journal Article2013Opportunistic exploitation: an overlooked pathway to extinctionTrends in Ecology and Evolution. 28(7): 409-413Download
PDF, 951 KB
How can species be exploited economically to extinction? Past single-species hypotheses examining the economic plausibility of exploiting rare species have argued that the escalating value of rarity allows extinction to be profitable. We describe an alternative pathway toward extinction in multispecies exploitation systems, termed ‘opportunistic exploitation’. In this mode, highly valued species that are targeted first by fishing, hunting, and logging become rare, but their populations can decline further through opportunistic exploitation while more common but less desirable species are targeted. Effectively, expanding exploitation to more species subsidizes the eventual extinction of valuable species at low densities. Managers need to recognize conditions that permit opportunistic depletion and pass regulations to protect highly desirable species when exploitation can expand to other species.
- Journal Article2013First record of Tristram's Bunting Emberiza tristrami from IndiaIndian Birds 8:134-135
- Journal Article2013Spatial and temporal variation in hornbill densities in Namdapha Tiger Reserve, Arunachal Pradesh, north-east IndiaTropical Conservation Science 6:734-748Download
PDF, 642 KB
Asian hornbill populations are declining across their ranges because of hunting and deforestation. Five of the 32 Asian hornbill species occur in north-east India. However, vital information on their abundance from the region remains scanty. Understanding spatiotemporal variation in densities provides crucial information for formulating effective conservation strategies based on species-specific abundance patterns and population trends. We examined spatiotemporal variation in densities of four hornbill species in the Namdapha Tiger Reserve, a site identified as an important site for hornbill conservation in Asia. We collected data through variable-width line transect sampling (effort=842.1 km) in the non-breeding season from 2009-12 to estimate hornbill densities. We had 458 detections of four hornbill species. We have estimated White-throated Brown Hornbill densities (7.9 birds/km2) for the first time throughout its entire range. The mean Rufous-necked Hornbill densities (6.9 birds/km2) were higher than those reported elsewhere. Great (3.9 birds/km2) and Wreathed Hornbill (16.1 birds/km2) densities were comparable with other sites. The peak densities of all hornbill species in November-December are among the highest reported from Asia. Wreathed Hornbill densities showed temporal variation peaking in November-December (68 birds/km2) and drastically declining by March-April (1.3 birds/km2), indicating seasonal altitudinal movement to low elevation areas outside the reserve during the breeding season. Our results underscored the spatial variation in hornbill distribution, with low densities of Great and the White-throated Brown hornbills in higher elevations. Our study demonstrates the global importance of Namdapha for hornbills, given its large area and high densities of four hornbill species.
- Popular Article2013Becoming one of themThe Hindu in School, 9 January
- Popular Article2013Rasgullas worth their tinThe Hindu in School, 13 March
- Popular Article2013The circle of lifeThe Hindu in School, 17 April
- Popular Article2013My books and their animalsThe Hindi in School, 23 January
- Popular Article2013The great crane projectThe Hindu in School, 20 February