- Popular Article2012A home for the house sparrowThe Hindu in School, 18 April
Jeganathan, P. (2012). A home for the house sparrow. The Hindu in School, 18 April.
- 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 Article2012Structure and dynamics of South East Indian seagrass meadows across a sediment gradientAquatic Botany, 98 (1): 34-39Download
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In this study we examine the influence of non-monsoon sediment arrival on the high-diversity SE Indian seagrass meadows of the Palk Bay and the Gulf of Mannar. We used a gradient-based approach to examine the influence of increasing sediment loads on species composition and shoot density. In addition, for the ubiquitous seagrass (Cymodocea serrulata), we tested the influence of sediment on its biomass and productivity. We identified three sites in Palk Bay and four sites in Gulf of Mannar (SE India) along a gradient of sediment input. At each of the seven locations, sediment traps were deployed to measure sedimentation rates. Nine seagrass cores were taken systematically along 50 m transects at a constant sub-tidal depth to measure shoot density and biomass. A few shoots of C. serrulata were marked to estimate the above ground seagrass growth rate. Our results indicate that sedimentation rates that ranged from 8.6 to 62.4 mg DW cm−2 d−1 could not explain species composition of the meadow or shoot density of the observed species. C. serrulata was, by far, the most abundant species and present in all sediment condi- tions. Sedimentation rates did not alter shoot elongation rates in C. serrulata, ranging from 1.54 ± 0.29 SD to 0.25 ± 0.02 SD cm d−1 , but in contrast, increased vertical rhizome elongation rate. This increase was reflected in an increase in below ground biomass along the sediment gradient (R2 = 0.582, p = 0.01). C. serrulata appears to be able to adapt to the sediment dynamics in this area by allocating resources to rhizomes and roots to counteract burial and stabilizing sediments. Given that siltation is one of the most important threats to seagrass meadows, understanding the species-specific adaptive mechanisms of seagrass species in these high-sediment, high diversity South Asian meadows is an important first step in ensuring their long-term survival and functioning
- Popular Article2012Dugongs, mermaids of the seaThe Hindu in School, 26 September
- Journal Article2012Conservation of the Asian small-clawed otter (Aonyx cinereus) in human-modified landscapes, Western Ghats, IndiaTropical Conservation Science 5: 67-78.Download
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Conservation in human-modified landscapes is important for riparian animals as their habitats extend linearly beyond adjoining protected areas. We examined occupancy and intensity of habitat use of Asian small-clawed otters in coffee and tea plantations and an adjoining protected area in the Western Ghats. We sampled 66 stream segments of 500 m length, using spraints as an indicator of habitat use. Several variables characterising the stream and shoreline were also measured. Occupancy, corrected for detection of spraints, was >0.75 in all three land use types, indicating widespread use of the riparian ecosystem in human-modified landscapes. Intensity of habitat use, however, was much lower in tea (2.08 spraints/500 m) and coffee (2.42) plantations than in the protected area (3.86). Using GLMs we identified the abundance of potential refuges (such as boulders and fallen trees), which was greater in the protected area, as the major factor influencing intensity of habitat use. Shoreline diversity, which was lowest in the tea plantation, might also be another factor. The retention of much of the riparian vegetation and the presence of forest fragments which provide refuges have led to wide occupancy of the tea and coffee plantations although with less intensive use. Sand mining, fishing and infrequent poaching might be other reasons for the relatively low use of human-modified landscape. This study highlights the need to retain remnant forests and riparian vegetation, and to control some human activities for integrated management of species like the small-clawed otter in both protected areas and adjoining human-modified habitats.
- Popular Article2012A thousand leopards in the SeaThe Hindu in School, 29 September
- Popular Article2012Trans-Himalaya: In the shadows of a giantCare4Nature
- Popular Article2012As the crow flies…The Hindu in School, 25 April
Jeganathan, P. (2012). As the crow flies… The Hindu in School, 25April.
- Popular Article2012The pigeon’s passengers.The Hindu Magazine, Sunday 6 May 2012, page 4.
Available here: http://www.thehindu.com/arts/magazine/article3387586.ece
Also here: http://www.thehindu.com/todays-paper/tp-in-school/the-pigeons-passengers/article3398790.ece
- Journal Article2012Patterns of species participation across multiple mixed-species flock types in a tropical forest in northeastern India.Journal of Natural History. 46(43-44):2749–2762.Download
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We studied mixed-species bird flocks in northeastern India to (a) develop a framework for quantifying species participation in mixed-species flocks, (b) characterize the ecology and behaviour of participant species, and (c) explore mechanisms influencing the coexistence of different mixed-species flock types. To characterize participation in mixed-species flocks, we implement a new method incorporating species abundances, minimizing potential biases in measuring participation arising from differences in the availability of flocking species. There are at least three distinct flock types in the lowland forests of northeastern India; these flock types differ in the body mass and vertical stratum use of participant species. The “core” of mixed-species flocks was composed of a species group that differed much more in their foraging method in comparison with “attendant” species. The exchange of benefits and minimization of interspecific competition might lead to, and maintain, heterogeneity in foraging methods among core species of mixed-species flocks.
- Popular Article2012Islands in peril: Conservation caveats.The Hindu Magazine, Sunday 26 February 2012, page 4.
- Journal Article2012To eat and not be eaten: modelling resources and safety in multi-species animal groups.PLoS ONE. 7(7): e42071.Download
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Using mixed-species bird flocks as an example, we model the payoffs for two types of species from participating in multi-species animal groups. Salliers feed on mobile prey, are good sentinels and do not affect prey capture rates of gleaners; gleaners feed on prey on substrates and can enhance the prey capture rate of salliers by flushing prey, but are poor sentinels. These functional types are known from various animal taxa that form multi-species associations. We model costs and benefits of joining groups for a wide range of group compositions under varying abundances of two types of prey–prey on substrates and mobile prey. Our model predicts that gleaners and salliers show a conflict of interest in multi-species groups, because gleaners benefit from increasing numbers of salliers in the group, whereas salliers benefit from increasing gleaner numbers. The model also predicts that the limits to size and variability in composition of multi-species groups are driven by the relative abundance of different types of prey, independent of predation pressure. Our model emphasises resources as a primary driver of temporal and spatial group dynamics, rather than reproductive activity or predation per se, which have hitherto been thought to explain patterns of multi-species group formation and cohesion. The qualitative predictions of the model are supported by empirical patterns from both terrestrial and marine multi-species groups, suggesting that similar mechanisms might underlie group dynamics in a range of taxa. The model also makes novel predictions about group dynamics that can be tested using variation across space and time.
- Popular Article2012என் பக்கத்து வீட்டு பழுப்புக் கீச்சான் (My friendly neighborhood Brown Shrike)தினமணி நாளிதழ் – கொண்டாட்டம் இணைப்பில். 26 பிப்ரவரி 2012. Dinamani- Tamil Newspaper. Date: 26thFebruary.
என்பக்கத்துவீட்டுபழுப்புக்கீச்சான்.தினமணிநாளிதழ் – கொண்டாட்டம்இணைப்பில். 26 பிப்ரவரி 2012. [Jeganathan, P. (2012)En pakkathu veetu pazuppu keechan.Dinamani- Tamil Newspaper. Date: 26thFebruary. (My friendly neighborhood Brown Shrike)]
- Popular Article2012காணாமல் போகும் சாலையோர உலகம் (On disappearing roadside trees)Puthiya Thalaimurai, Tamil Weekly Magazine, 30 August
காணாமல் போகும் சாலையோர உலகம். காக்கைக் குருவி எங்கள் ஜாதி தொடர்-8. புதிய தலைமுறை. 30ஆகஸ்டு 2012. [Jeganathan, P. (2012).Kanamal Pogum Salaiyora Ulagam. Kakkai Kuruvi Engal Jathi-Series, Article No.8 Puthiya Thalaimurai. 30th August 2012. (On disappearing roadside trees)]
- Popular Article2012இடைவெளியும் இடையூறும் (Canopy gaps and obstacles: Canopy gaps above the forest roads and their impact on arboreal mammals of Western Ghats)Dinamani Tamil Newspaper. 29 January 2012.
இடைவெளியும் இடையூறும். தினமணி நாளிதழ் – கொண்டாட்டம் இணைப்பில். 29 ஜனவரி 2012. 3ம் பக்கம். [Jeganathan, P. (2012). Idaiveliyum Idayoorum. Dinamani- Tamil Newspaper. Date: 29th January (Canopy gaps and obstacles: Canopy gaps above the forest roads and their impact on arboreal mammals of Western Ghats) ]
Link for this article here.
- Popular Article2012காக்கா…காக்க...(On Crows)புதிய தலைமுறை. 12ஜூலை 2012 Puthiya Thalaimurai. 12th July 2012
- Journal Article2012Distance-related thresholds and influence of the 2004 tsunami on damage and recovery patterns of coral reefs in the Nicobar IslandsCurrent Science 102:1199–1205
The earthquake and tsunami of 2004 resulted in the devastation of marine and coastal ecosystems across the Indian Ocean. However, without adequate baseline information it has been difficult to properly gauge its full impact. The reefs of the Nicobar Islands in the Bay of Bengal lie on a path that ranges from 190 to 500 km from Banda Aceh, the epicentre of the 2004 tsunami. In 2008, we recorded benthic damage as a result of the tsunami to reefs off 14 Nicobar Islands across a gradient of distance from the epicentre. A clear pattern was observed in the demographic structure of the most abundant coral genera, Acropora and Porites across the distance gradient. Significantly, for the largest coral individuals of both genera (> 50 cm diameter), there were distinct threshold effects – their abundance declining dramatically in reefs closer than 350 km from the epicentre. Corals between 20 and 50 cm diameter also increased with distance from the epicentre, but in a more linear fashion. Smaller size classes either showed no apparent trend (Acropora) or decreased linearly (Porites) with distance. These gen- era represent very different life-history strategies: Acropora is fast-growing and highly susceptible to a range of disturbances, while Porites typically grows slowly but is resistant to disturbance. The fact that both genera showed similar thresholds indicates that, close to the epicentre, the impact of the earthquake and tsunami was large enough to override any species- specific resistance. Also, algal cover was also much higher than at locations further north, linked to higher coral mortality at these locations. However, the fact that smaller size class coral individuals were rela- tively abundant and even increased close to the ep centre indicates possible paths of reef recovery after the catastrophe.
- Popular Article2012Of tamarind and toleranceThe Hindu Magazine, 17 June 2012, page 4.
Link to this article here.
- Popular Article2012முந்தோன்றி மூத்தவரே. (On South Indian Primates)புதிய தலைமுறை. 16ஆகஸ்டு 2012. Puthiya Thalaimurai. 16th August 2012.
- Popular Article2012A problem landscape in the Western GhatsHornbill, April-June, 2012 : 4-8