- Journal Article2015Tracking seed fates of tropical tree species: evidence for seed caching in a tropical forest in north-east IndiaPLoS ONEDOI: 10.1371/journal.pone.0134658Download
PDF, 1.3 MB
Rodents affect the post-dispersal fate of seeds by acting either as on-site seed predators or as secondary dispersers when they scatter-hoard seeds. The tropical forests of north-east India harbour a high diversity of little-studied terrestrial murid and hystricid rodents. We examined the role played by these rodents in determining the seed fates of tropical evergreen tree species in a forest site in north-east India. We selected ten tree species (3 mammal-dispersed and 7 bird-dispersed) that varied in seed size and followed the fates of 10,777 tagged seeds. We used camera traps to determine the identity of rodent visitors, visitation rates and their seed-handling behavior. Seeds of all tree species were handled by at least one rodent taxon. Overall rates of seed removal (44.5%) were much higher than direct on-site seed predation (9.9%), but seed-handling behavior differed between the terrestrial rodent groups: two species of murid rodents removed and cached seeds, and two species of porcupines were on-site seed predators. In addition, a true cricket,Brachytrupessp., cached seeds of three species underground. We found 309 caches formed by the rodents and the cricket; most were single-seeded (79%) and seeds were moved up to 19 m. Over 40% of seeds were re-cached from primary cache locations, while about 12% germinated in the primary caches. Seed removal rates varied widely amongst tree species, from 3% inBeilschmiedia assamicato 97% inActinodaphne obovata. Seed predation was observed in nine species.Chisocheton cumingianus(57%) andPrunus ceylanica(25%) had moderate levels of seed predation while the remaining species had less than 10% seed predation. We hypothesized that seed traits that provide information on resource quantity would influence rodent choice of a seed, while traits that determine resource accessibility would influence whether seeds are removed or eaten. Removal rates significantly decreased (p< 0.001) while predation rates increased (p= 0.06) with seed size. Removal rates were significantly lower for soft seeds (p= 0.002), whereas predation rates were significantly higher on soft seeds (p= 0.01). Our results show that murid rodents play a very important role in affecting the seed fates of tropical trees in the Eastern Himalayas. We also found that the different rodent groups differed in their seed handling behavior and responses to changes in seed characteristics.
- Popular Article2015Abhi to the rescue!The Hindu in School, 12 AugustDownload
PDF, 1.43 MB
- Popular Article2015Back home to the healing forestThe Hindu in School, 19 August
- Journal Article2015Fish community reassembly after a coral mass mortality: higher trophic groups are subject to increased rates of extinctionEcology Letters 18(5): 451–461Download
PDF, 893 KB
Since Gleason and Clements, our understanding of community dynamics has been influenced by theories emphasising either dispersal or niche assembly as central to community structuring. Determining the relative importance of these processes in structuring real-world communities remains a challenge. We tracked reef fish community reassembly after a catastrophic coral mortality in a relatively unfished archipelago. We revisited the stochastic model underlying MacArthur and Wilson’s Island Biogeography Theory, with a simple extension to account for trophic identity. Colonisation and extinction rates calculated from decadal presence-absence data based on (1) species neutrality, (2) trophic identity and (3) site-specificity were used to model post-disturbance reassembly, and compared with empirical observations. Results indicate that species neutrality holds within trophic guilds, and trophic identity significantly increases overall model performance. Strikingly, extinction rates increased clearly with trophic position, indicating that fish communities may be inherently susceptible to trophic downgrading even without targeted fishing of top predators.
- Journal Article2015Wetland loss and waterbird use of wetlands in Palwal district, Haryana, India: The role of agriculture, urbanization and conversion to fish pondsWetlands. DOI 10.1007/s13157-014-0600-8Download
PDF, 1.15 MB
Wetlands in tropical and sub-tropical landscapes
are experiencing changes and loss due to urbanization and
intensive human use, but there is sparse detailed understanding
of how these affect use by wetland-dependent birds.
Urbanization and conversion of community wetlands to private
fish ponds are occurring rapidly in Haryana state in north
India. We conducted a study in Palwal district, Haryana in
2013–2014 to simultaneously understand (i) rates and reasons
for wetland loss between 1970s and 2000s, and (ii) relative
importance of location (towns/ villages versus those amid
agriculture) versus site-specific variables on the winter abundance of 31 waterbird species in these fish ponds. Wetland
extent reduced by 52 %, and average wetland size reduced by
42 % between 1970s and 2000s. Expansion of urban areas
converted 105 agricultural wetlands to town wetlands.
Wetlands of different locations could not be differentiated
using waterbird abundance suggesting that wetland conditions
have been homogenized, in part due to conversions to fish
ponds and in part due to urban expansions. Focal waterbird
abundance was affected more due to human activities relative
to location or vegetation. A complex combination of current
management practices and historical determinants of wetland persistence appear to be driving waterbird use of wetlands in
locations like Palwal.
- Popular Article2015Current ecological concerns in the power sector: options to avoid or minimise impactsPages 89-100 in M N Goswami and P Chaudhry (editors) An Epochal Shift in the Idea of India-Meeting aspirations? IPPAI Knowledge Report, Independent Power Producers Association of India, New Delhi.
- Popular Article2015The spit in the grass!The Hindu in School, 2 September
- Journal Article2015Does livestock benefit or harm snow leopards?Biological Conservation, 190: 8-13
Large carnivores commonly prey on livestock when their ranges overlap. Pastoralism is the dominant land use type across the distributional range of the endangered snow leopard Panthera uncia. Snow leopards are often killed in retaliation against livestock depredation. Whether livestock, by forming an alternative prey, could potentially benefit snow leopards, or, whether livestock use of an area is detrimental to snow leopards is poorly understood. We examined snow leopard habitat use in a multiple use landscape that was comprised of sites varying in livestock abundance, wild prey abundance and human population size. We photographically sampled ten sites (average size 70 sq. km) using ten camera traps in each site, deployed for a period of 60 days. Snow leopard habitat use was computed as a Relative Use Index based on the total independent photographic captures and the number of snow leopard individuals captured at each site. We quantified livestock abundance, wild prey abundance, human population size and terrain ruggedness in each of the sites. Key variables influencing snow leopard habitat use were identified using Information Theory based model selection approach. Snow leopard habitat use was best explained by wild prey density, and showed a positive linear relationship with the abundance of wild ungulates. We found a hump-shaped relationship between snow leopard habitat use and livestock stocking density, with an initial increase in habitat use followed by a decline beyond a threshold of livestock density. Our results suggest that in the absence of direct persecution of snow leopards, livestock grazing and snow leopard habitat use are potentially compatible up to a certain threshold of livestock density, beyond which habitat use declines, presumably due to depressed wild ungulate abundance and associated anthropogenic disturbance.
- Popular Article2015Stupendous spidersThe Hindu in School, 16 September
- Journal Article2015Erosion of Traditional Marine Management Systems in the Face of Disturbances in the Nicobar ArchipelagoHuman Ecology, DOI 10.1007/s10745-015-9781-x
- Popular Article2015On the lineThe Caravan Magazine, September 2015.
A remote island's fight to save a remarkable grouper spawning aggregation.
- Report2015Hornbill Nest Adoption Program - 2015 Breeding SeasonHNAP 2015 Report
- Popular Article2015How the tangkung lost its tailThe Hindu in School, 1 OctoberDownload
PDF, 1.85 MB
- Art & Literary2015Nature without Bordershttp://peepli.org/project/naturewithoutborders/
In India, people and wildlife share common spaces. But as development gets fast-tracked, the delicate, value-based balance is tilting; This year-long project explores the complex relationships between Man and Nature
- Journal Article2015Landscape scale habitat suitability modelling of bats in the Western Ghats of India:Bats like something in their teaBiological Conservation 191: 529-536.Download
PDF, 1.92 MB
To conserve biodiversity it is imperative that we understand how different species respond to land use change, and determine the scales at which habitat changes affect species' persistence. We used habitat suitability models (HSMs) at spatial scales from 100–4000 m to address these concerns for bats in the Western Ghats of India, a biodiversity hotspot of global importance where the habitat requirements of bats are poorly understood. We used acoustic and capture data to build fine scale HSMs for ten species (Hesperoptenus tickelli, Miniopterus fuliginosus, Miniopterus pusillus, Myotis horsfieldii, Pipistrellus ceylonicus, Megaderma spasma, Hipposideros pomona, Rhinolophus beddomei, Rhinolophus indorouxii and Rhinolophus lepidus) in a tea-dominated landscape. Small (100–500 m) scale habitat variables (e.g. percentage tea plantation cover) and distances to habitat features (e.g. distance to water) were the strongest predictors of bat occurrence, likely due to their high mobility, which enables them to exploit even small or isolated foraging areas. Most species showed a positive response to coffee plantations grown under native shade and to forest fragments, but a negative response to more heavily modified tea plantations. Two species were never recorded in tea plantations. This is the first study of bats in tea planta- tions globally, and the first ecological Old World bat study to combine acoustic and capture data. Our results suggest that although bats respond negatively to tea plantations, tea-dominated landscapes that also contain forest fragments and shade coffee can nevertheless support many bat species.
- Journal Article2015Demographic superiority with increased logging in tropical understorey birdsJournal of Applied Ecology, 52 (5): 1374-1380
- Book2015What's that bird? Common birds of India
Flashcards of birds for children
- Book2015Birds of peninsular India: a pocket guide to 135 familiar birds
- Popular Article2015A day to celebrate the dugong-a story of their conservationAndaman Chronicle, 04, October
- Popular Article2015வானில் பறக்கும் புள்களைத் தேடி. (On my eBirding Big Year)தி ஹிந்து சித்திரை மலர். The Hindu Sithirai Malar. January 2015