Publications
- Journal ArticleIn pressMixed fortunes: old expansion and recent decline in population size of a subtropical montane primate, the Arunachal macaquePLoS One
- Journal ArticleIn pressGoral Nemorhaedus goralIn: A. J. T. Johnsingh and N. Manjrekar (eds.) Mammals of South Asia: ecology, behaviour and conservation. Permanent Black, Delhi.
- Journal ArticleIn pressSerow Nemorhaedus sumatraensisIn: A. J. T. Johnsingh and N. Manjrekar (eds.) Mammals of South Asia: ecology, behaviour and conservation. Permanent Black, Delhi.
- Book ChapterIn pressConflicts over snow leopard conservation and livestock productionConservation Conflicts, Redpath S, Young J, Gutierrez R, Wood K (eds.), Cambridge University Press.
- Journal ArticleIn pressAnts on Clerodendrum infortunatum: Disentangling Effects of Larceny and HerbivoryEnvironmental Entomology
https://doi.org/10.1093/ee/nvy090
Abstract
Nectar larcenists extract nectar from flowers without pollinating them. A reasonable expectation is that any form of nectar larceny should have a detrimental effect on the plant’s reproductive success. However, studies reveal an entire range of effects, from highly negative to highly positive. This variation in effect may be partly explained by additional, unmeasured, effects of nectar larcenists on plants. In a study system where two ant species Tapinoma melanocephalum (Fabr.) (Hymenoptera: Formicidae) and Trichomyrmex destructor (Jerd.) (Hymenoptera: Formicidae) act as nectar larcenists, we examined the effect of larceny on the female reproductive success of Clerodendrum infortunatum Gaertn. (Lamiales: Lamiaceae) in rain forest fragments of the Western Ghats, India. This was done through a combination of field observations and a series of field experiments looking at the effects of excluding ants from inflorescences. We found that T. destructor reduces fruit set considerably. Rather than this being a consequence of nectar larceny, however, our experiments show that the negative effect arises instead from the herbivorous behavior of the ant. At a population level, both ant species prefer edges over interiors of forest patches, spatially concentrating the interaction zone to forest edges. Simultaneously considering multiple ecological interactions and disentangling their relative contributions might explain the large variation across species in the observed effect of larceny. The overall population effect of nectar larceny and herbivory is likely to depend on the spatial structuring of plants and ants.
- Journal ArticleIn pressVariability in gut passage times for Asian hornbills for large-seeded speciesSarawak Museum Forestry Journal
- Journal Article2019Sympatric cranes in northern Australia: abundance, breeding success, habitat preference and dietEmu - Austral Ornithology 119(1): 79-89. https://doi.org/10.1080/01584197.2018.1537673Download
PDF, 2.33 MB
Sympatric breeding of Sarus Cranes (Antigone antigone) and Brolga (A. rubicunda) occurs only in northern Queensland, Australia but factors contributing to this unique sympatry are unknown. Large-scale developments currently planned in this region, with potentially major impacts on cranes, create an urgent need to understand the ecological requirements of each crane species. We carried out a multi-floodplain landscape-scale survey during April-May 2017 and derived metrics for several ecological aspects for the first time for both crane species. The abundance of the two species differed between the floodplains. Both crane species synchronised nest-initiation with rainfall (November to March). Breeding success was higher than past estimates anywhere, with 60% of Sarus Crane pairs and 50% of Brolga pairs fledging chicks. Sarus Cranes preferred four riverine Eucalyptus-dominated regional ecosystems, with 10% using open habitats. Brolgas preferred two non-wooded regional ecosystems, but 32% shared Eucalyptus-dominated regional ecosystems with Sarus Cranes. Stable isotope analyses revealed Sarus diet to be comprised of more diverse vegetation than Brolgas, while Brolgas fed across a wider range of trophic levels. The ecology of Gulf cranes closely matched habits of Sarus Cranes in south Asia, despite disparate conditions suggesting considerable species plasticity. The diverse habitats of the Gulf and varying diet appear to facilitate the cranes’ sympatry, and our study provides basic data for developing long-term conservation plans in the face of development activities.
- Poster2019How Hornbills Breed: Wreathed HornbillsDownload
PDF, 2.34 MB
Great Hornbills poster up here: http://ncf-india.org/publications/1101
- Poster2019How Hornbills Breed: Great HornbillsDownload
PDF, 4.96 KB
Wreathed Hornbills poster up here: http://ncf-india.org/publications/1100
- Journal Article2019Sampling bias in snow leopard population estimation studiesPopulation Ecology 10.1002/1438-390X.1027Download
PDF, 10.1 MB
Accurate assessments of the status of threatened species and their conservation planning require reliable estimation of their global populations and robust monitoring of local population trends. We assessed the adequacy and suitability of studies in reliably estimating the global snow leopard (Panthera uncia) population. We compiled a dataset of all the peer-reviewed published literature on snow leopard population estimation. Metadata analysis showed estimates of snow leopard density to be a negative exponential function of area, suggesting that study areas have generally been too small for accurate density estimation, and sampling has often been biased towards the best habitats. Published studies are restricted to six of the 12 range countries, covering only 0.3–0.9% of the presumed global range of the species. Re-sampling of camera trap data from a relatively large study site (c.1684 km2) showed that small-sized study areas together with a bias towards good quality habitats in existing studies may have overestimated densities by up to five times. We conclude that current information is biased and inadequate for generating a reliable global population estimate of snow leopards. To develop a rigorous and useful baseline and to avoid pitfalls, there is an urgent need for (a) refinement of sampling and analytical protocols for population estimation of snow leopards (b) agreement and coordinated use of standardized sampling protocols amongst researchers and governments across the range, and (c) sampling larger and under-represented areas of the snow leopard's global range.
- Popular Article2019Eight-eyed and everywhereThe Hindu Sunday Magazine, 23 February
Jostling for column space among reports of new snakes, reptiles and frogs discovered, are a particularly delightful and large group of spiders called jumping spiders. These little arachnids are known for their astonishing array of cognitive abilities and are considered model organisms to study behaviour, as well as answer theoretical questions about communication, foraging, courtship, mating and parental care.
- Journal Article2019Roosting ecology of Black-Headed Ibis (Threskiornis melanocephalus) in urban and rural areas of southern Rajasthan, IndiaWaterbirds 42(1): 51-60.
The roosting ecology of most waterbird species is poorly known and even less is known from southern Asia, where many species inhabit human-modified areas. Roosting ecology of the Black-headed Ibis (Threskiornis melanocephalus) was studied in urban and rural settings in southern Rajasthan, India. Analyses focused on assessing whether site characteristics varied between nest sites, urban and rural roost sites, and paired sites (i.e., a waterbird roost site near Black-headed Ibis roosts but without Black-headed Ibis). Additionally, the hypothesis that factors affecting Black-headed Ibis numbers at roosts would be similar at urban and rural sites was tested. Tree characteristics (canopy cover, girth at breast height) were different (P < 0.05) between nest and roost sites. Urban roost sites experienced 2.3 times greater disturbance than rural roost sites. Paired site characteristics were similar to urban roost sites (multi response permutation procedure, significance of δ = 0.3), but were dissimilar to rural roost sites. Co-occurring roosting bird assemblages were significantly different between roosts and paired sites (significance of δ < 0.01) in urban and rural settings. Black-headed Ibis numbers at urban roosts were influenced by multiple variables, but models showed considerable ambiguity at rural sites. Results strongly suggest that including roost sites in a species status assessment is important.
- Popular Article2019பறவைகளை வடிக்கும் இயற்கை ஓவியர் (Interview with Sivakumar, An artist and birder from The Forest Way, Tiruvannamalai)The Hindu Magazine - Pongal Special issue– January 2019. Pp – 130-137
Jeganathan, P. (2019). Paravaigalai Vadikkum Iyarkai Oviyar (The Hindu link here).
- Popular Article2019கருவயிற்று ஆலாவின் வாழ்க்கை (Karuvayitru Alavin Vazkkai). (On Black-bellied tern and sand mining in Kaveri river)The Hindu Tamil News Daily, Uyirmoochu Supplement. 12th January 2019.
Jeganathan, P. (2019). Karuvayitru Alavin Vazkkai (On Black-bellied tern and sand mining in Kaveri river). The Hindu Tamil News Daily, Uyirmoochu Supplement. 12th January 2019.Link here.
- Popular Article2019Leaves us speechlessThe Hindu. In school, 6th January.Download
PDF, 11.2 MB
Jeganathan, P. (2019). Leaves us speechless. The Hindu. In school, 6th January.
- Popular Article2019பறவைப் பித்தர்கள் (Crazy birders of Tamil Nadu)The Hindu Tamil News Daily, Uyirmoochu Supplement. 16th March 2019.
Jeganathan, P. (2019). Paravaip Pithargal (on birders of Tamil Nadu). Link here.
- Journal Article2019Focal plant and neighbourhood fruit crop size effects on fruit removal by frugivores in a semi-arid landscape invaded by Lantana camara L.Current Science 116 (3) 405-412Download
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- Dataset2019Data from: Large frugivores matter: insights from network and seed dispersal effectiveness approacheshttps://doi.org/10.5061/dryad.m20hf10
We evaluated the role of large avian frugivores in a plant‐disperser community by a) determining whether the plant‐disperser community was modular, with a distinct community of large frugivores (thereby highlighting their importance), b) determining relative qualitative and quantitative roles played by large‐bodied frugivores vis‐à‐vis other frugivores and c) determining impacts of large‐bodied frugivore loss on the plant‐disperser community. The study was carried at a tropical forest site in north‐east India which is part of the Eastern Himalaya Biodiversity Hotspot. We collected tree watch data (2055 h) from 46 tree species, which represented 85% of tree species that are predominantly bird‐dispersed in the area. We found that the plant‐disperser community was modular, with a distinct module of large‐seeded tree species and large frugivores. Intermediate‐sized frugivores such as barbets and bulbuls were the most connected, while large‐sized frugivores, such as hornbills and imperial‐pigeons were moderately well‐connected. Qualitative and quantitative roles played by different dispersers varied across the gradient of frugivore body size. Hornbills, the largest avian frugivores, consumed a significantly greater number of fruits and swallowed larger proportions of fruits compared to other avian groups. In comparison to similar‐sized frugivores, imperial‐pigeons fed on larger‐sized fruits, highlighting their importance for dispersal of large‐seeded plants. Under simulated extinction scenarios, larger extinction cascades weren't necessarily caused by larger frugivores, however, extinctions of certain large‐bodied frugivores (hornbills, imperial‐pigeons) caused extinction cascades. Integrating information from networks and seed dispersal effectiveness approaches enabled a better understanding of large frugivore role in a plant‐disperser community. While large‐bodied frugivores may not be playing a central role in plant‐disperser communities, they are crucial as seed dispersal service providers for large‐seeded plants. In conjunction with the reported local extinctions of large frugivores like hornbills from the south Asian region, this study's findings highlight the irreplaceable quantitative and qualitative impacts that tropical plant communities are likely to experience in the future.
- Journal Article2019Distribution and activity pattern of stone marten Martes foina in relation to prey and predatorsMammalian Biology; Volume 96, May 2019, Pages 110-117Download
PDF, 1.56 MB
Small carnivores are expected to optimize their activity to maximize prey capture and minimize their encounter with predators. We assessed the activity pattern of the stone marten
Martes foinain relation to its potential prey, the Himalayan woolly hare Lepus oiostolus and the Royle’s pika Ochotona roylei, and its predators, the red fox Vulpes vulpesand the free-ranging dog Canis familiaris. Using three years of camera trapping data from the Indian Trans-Himalaya, we estimated individual and pair-wise spatio-temporal niche width and overlap, respectively, using Levins’ asymmetric index. Stone martens showed limited space use (spatial niche width 0.16) and nocturnal activity (temporal niche width 0.35). They had high temporal (0.75) and low spatial overlap (0.05) with hares; while they had relatively low temporal (0.33) but higher spatial overlap (0.29) with pikas. Red foxes showed relatively high temporal (1.21) and spatial (0.75) overlap with martens, while free-ranging dogs showed low temporal (0.23) and spatial (0.03) overlap with martens. Although restricted space and time use by pikas might help martens track pikas even with relatively low spatio-temporal overlap, martens may be benefiting from higher temporal overlap with hares. While martens seem to be co-existing with foxes, their nocturnal activity might be driven by a trade-off between consuming prey and avoidance of diurnal predators like dogs. - Journal Article2019Eastern Imperial Eagle Aquila heliaca at Dibru-Saikhowa National Park, AssamIndian Birds Vol. 15 No. 2Download
PDF, 908 KB
