Nair T.,Wildlife Conservation Society |
Nair T.,Center for Wildlife Studies |
Thorbjarnarson J.B.,Wildlife Conservation Society |
Aust P.,Center for Herpetology |
And 2 more authors.
Journal of Applied Ecology
India's Chambal River hosts the largest population of the critically endangered gharial. Boat-based daylight surveys to date only provide indices of relative abundance, without measures of survey bias or error. No attempt to quantify detection probabilities in these surveys has yet been made, and thus, absolute density estimates of this population remain unknown. We surveyed 75 km of the River Chambal and photographed individual gharials for capture-recapture analysis. The total sampling effort yielded 400 captures. Population closure was supported (z = -1·48, P = 0·069), and closed-population models were used to estimate abundances. Models were selected using the Akaike Information Criterion (AIC) index of model fit. The best model estimated 231 ± 32 adult, 83 ± 23 subadult and 89 ± 19 juvenile gharials (Mean ± SE), respectively, while the model-averaged estimate was 220 ± 28 adult, 76 ± 16 subadults and 93 ± 16 juvenile gharials, respectively. The best model estimated absolute densities of 3·08 ± 0·43, 1·11 ± 0·3 and 1·19 ± 0·25 adult, subadult and juvenile gharials km -1, respectively, while the model-averaged estimate was 2·93 ± 0·37, 1·01 ± 0·21 and 1·24 ± 0·21 adult, subadult and juvenile gharials km -1, respectively, compared with relative densities of 0·94, 0·45 and 0·30 adult, subadult and juvenile gharials km -1, respectively, from boat-based daylight surveys. On the basis of our best model, we suggest a detection probability based correction factor of 3·27, 2·47 and 3·97 to boat-based daylight survey estimates of adult, subadult and juvenile gharials, respectively. Synthesis and applications. Used within the framework of capture-recapture analysis, photoidentification provides a reliable and noninvasive method of estimating population size and structure in crocodilians. We also opine that without determining the current status of gharials, highly intensive strategies, such as the egg-collection and rear-and-release programmes being implemented currently, initiated on the basis of underestimates of population sizes, are unwarranted and divert valuable conservation resources away from field-based protection measures, which are essential in the face of threats like hydrologic diversions, sand mining, fishing and bankside cultivation. © 2012 The Authors. Journal of Applied Ecology © 2012 British Ecological Society. Source
Meganathan P.R.,National Analysis Center |
Dubey B.,National Analysis Center |
Jogayya K.,National Analysis Center |
Whitaker N.,Center for Herpetology |
Haque I.,National Analysis Center
Molecular Ecology Resources
Illegal hunting has been a major threat for the survival of wildlife fauna, including the three crocodile species that India harbours: Crocodylus palustris, Crocodylus porosus and Gavialis gangeticus. Although law prevents trade on these species, illicit hunting for trade continues to threaten the survival of these endangered species; conservation strategies therefore require a rapid molecular identification technique for Indian crocodiles. A multiplex polymerase chain reaction (PCR) assay with species-specific primers, considered as one of the most effective molecular techniques, is described herein. The primers were designed to yield species-specific sized amplicons. The assay discriminates the three Indian crocodile species unambiguously within a short time period using only simple agarose gel electrophoresis. We recommend this multiplex PCR assay to be used in the identification of Indian crocodile species. © 2010 Blackwell Publishing Ltd. Source
Zachariah A.,Beagle |
Cyriac V.P.,Indian Institute of Science |
Chandramohan B.,SciGenom Research Foundation |
Ansil B.R.,Vilayilveedu |
And 4 more authors.
Two new species of rhacophorid bush frogs of the genus Raorchestes are described from the tropical montane wet forests in the Silent Valley National Park in the Nilgiri Hills, a high horst in the Western Ghats, India. Both species can be differentiated from their congeners by morphological and bioacoustic characters as well as differences in the mitochondrial 16S gene. Advertisement calls of the two new species are provided and tentative insights into the phylogenetic position discussed. Despite recent revisions of this genus from the Western Ghats, and the fact that the Silent Valley National Park is one of the most important and well-surveyed protected areas, the results of this study highlight the overlooked diversity in this area. © 2016 Deutsche Gesellschaft für Herpetologie und Terrarienkunde e.V. (DGHT), Mannheim, Germany. Source
Brien M.L.,Charles Darwin University |
Brien M.L.,Wildlife Management International Pty. Ltd |
Lang J.W.,University of Minnesota |
Webb G.J.,Charles Darwin University |
And 3 more authors.
We examined agonistic behaviour in seven species of hatchling and juvenile crocodilians held in small groups (N = 4) under similar laboratory conditions. Agonistic interactions occurred in all seven species, typically involved two individuals, were short in duration (5-15 seconds), and occurred between 1600-2200 h in open water. The nature and extent of agonistic interactions, the behaviours displayed, and the level of conspecific tolerance varied among species. Discrete postures, non-contact and contact movements are described. Three of these were species-specific: push downs by C. johnstoni; inflated tail sweeping by C. novaeguineae ; and, side head striking combined with tail wagging by C. porosus . The two long-snouted species (C. johnstoni and G. gangeticus) avoided contact involving the head and often raised the head up out of the way during agonistic interactions. Several behaviours not associated with aggression are also described, including snout rubbing, raising the head up high while at rest, and the use of vocalizations. The two most aggressive species (C. porosus, C. novaeguineae) appeared to form dominance hierarchies, whereas the less aggressive species did not. Interspecific differences in agonistic behaviour may reflect evolutionary divergence associated with morphology, ecology, general life history and responses to interspecific conflict in areas where multiple species have co-existed. Understanding species-specific traits in agonistic behaviour and social tolerance has implications for the controlled raising of different species of hatchlings for conservation, management or production purposes. © 2013 Brien et al. Source
Abraham R.K.,University of Kansas |
Abraham R.K.,Center for Herpetology |
Mathew J.K.,Karakkattupeedicayil |
Cyriac V.P.,Indian Institute of Science |
And 3 more authors.
The Western Ghats biodiversity hotspot is a recognized center of rhacophorid diversity as demonstrated by several recent studies. The endemic genus Ghatixalus is represented by two species from two separate high-elevation regions within the Ghats. Here, we describe a third species that can be distinguished by morphological and larval characters, as well as by its phylogenetic placement. © 2015 Magnolia Press. Source