Technical Reports/Books/Manuals

Permanent URI for this communityhttp://192.168.202.180:4000/handle/123456789/7

Browse

Author: search.filters.author.Vasudevan, K.Has files: Yes

Search Results

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Ecology of two endemic turtles in the Western Ghats
    (Wildlife Institute of India, Dehradun, 2010) Vasudevan, K.; Pandav, B.; Deepak, V.
    This project was initiated on the 16th January 2006 with an aim to generate natural history information on two out of the three endemic species of terrestrial turtles. India has 28 species of freshwater turtles and tortoises, of them three species are endemic. The endemic species: Caneturtle, Vijayachelys silvatica; Travancore tortoise Indotestudo travancorica; Leith’s softshell Nilssonia leithii, are restricted to the southern peninsula and the Western Ghats. In this study the focal species were the Cane turtle and the Travancore tortoise which had their distribution in the Western Ghats. The objectives of the project were (i) to estimate the population density of Travancore tortoise and cane turtle in a fragmented landscape; (ii) to quantify the diet of these two species and describe the feeding ecology with respect to their role in seed dispersal; (iii) to identify threats to the turtle population based on their habitat use ranging pattern and food habits and recommend measures for their conservation; (iv) to carry out a survey of these two species along the Western Ghats to ascertain the exact distribution in the context of Protected area network in the region. The study employed methods to study the population, diet and ranging patterns of the Cane turtle and the Travancore tortoise in Anamalai and Parambikulam Tiger Reserves. In the case of Travancore tortoise, the animals were searched on forest trails scattered in the reserves and repeated over three years to determine the proportion of area occupied accounting for imperfect detections. These surveys revealed that about 82% of the area surveyed is occupied by the tortoise, suggesting that the reserves hold sizeable population of the tortoise. The occupancy of the Travancore tortoise was negatively influenced by anthropogenic disturbance levels and positively influenced by the availability of water bodies and grass marsh in different sites. Only 35% of the sites occupied by the species resulted in detections, suggesting that it was cryptic. The important constituents of its diet were grass, other plant matter, invertebrates and other animal matter. The vayal (grass openings within woodland) habitat might be crucial for foraging by Travancore tortoise. The five individuals that were radio-tagged used an area from 5 to 35 ha covering evergreen, bamboo and open scurb-grass marshes. The animals spent about 98% of their time under leaf litter, logs, rocks crevices, tree holes, termite or pangolin burrows, bamboo tickets and under grass. In the case of cane turtle, various search methods employed did not yield detections and therefore, an intensive area was combed intensively. This resulted in detections of the elusive cane turtle. During the study spanning over four years, 42 ha of the evergreen forests in the reserve resulted in sightings of 27 different individuals of the cane turtle. This suggests that the species occurs in high density in the evergreen forests. Six cane turtles were fixed with radio-transmitters and monitored for two years. They used an area from 3.5 to 14.2 ha restricted to the evergreen forests alone. They also had extensive overlap in their home-ranges, suggesting no territoriality in the species. The movement of the animals were influenced by temperature and rainfall in the intensive study area. Diet of the species consisted of forest floor invertebrates, seeds and other plant material. The field observations on feeding on a large land snail and aggressive encounters between males of the cane turtle were the highlights of the study on the species. A survey of the three endemic species of turtles was taken up in the fifth year of the project. The survey involved visiting 12 sites in the states of Karnataka and Tamil Nadu. The potential sites where the species might be found were visited and the locals were interviewed in order to document the occurrence of the species. This resulted in one new locality record for cane turtle and two new records for Travancore tortoise. The Leith’s softshell was reported from five different locations in Karnataka and Tamil Nadu based on the interviews with locals. The sites occupied by the species were located within and outside protected areas. So far the study has resulted in three peer reviewed publications and two presentations in international conference. Based on the findings of the study it could be inferred that the Travancore tortoise is sensitive to human disturbance. This might be the consequence of exploitation of the animal by the locals in the reserves where the study was conducted. It is not uncommon to find locals using domesticogs during their forays into the forest. We speculate that there is some level of subsistence exploitation of the species in the region. The behaviour and ranging pattern of the species make them cryptic for detection by humans, but vulnerable to detection by domestic dogs. The study revealed that there is poor awareness among wildlife protection staff in the reserves on the species in general. Increasing the awareness of the staff could result in curbing subsistence exploitation of the species in the reserves. The vayals in the reserve are crucial habitats for the species; therefore, their protection and monitoring should be of importance for the persistence of the tortoise population. In the case the cane turtle, contrary to our initial expectations they survive in high densities (60 individuals in 1 sq. km) in the middle and low elevation evergreen forests (between 10 – 1000 m above mean sea level). The Karian Shola National Park is having a large population of this species which is of importance of the management of the protected area. The species is extremely stenotypic, showing strong preference to a narrow range of microclimatic variation prevailing in evergreen forests that are below 1000 m elevation in the Western Ghats. This indicates that the low elevation evergreen forest areas are crucial habitats for the species. Our intensive study on the species spanning over four years did not yield much information on the reproductive ecology of the species, because of their secretive lives. We recommend studies on the reproductive biology of the species, which might be important in the context of conservation breeding of the species. In the case of Leith’s softshell, we suggest extensive surveys to document the distribution, the status of population and, the genetic and morphological variation in the populations in peninsular India.
  • No Thumbnail Available
    Item
    Barcoding anurans of India
    (Wildlife Institute of India, Dehradun, 2010) Vasudevan, K.; Aggarwal, Ramesh K.; Dutta, S.K.
  • No Thumbnail Available
    Item
    Macroecology of terrestrial herpetofauna in Andaman and Nicobar Archipelago
    (Wildlife Institute of India, Dehradun, 2014) Harikrishnan, S.; Vasudevan, K.; Das, Abhijit; Choudhury, B.C.; Dutta, S.K.; Das, Indraneil
    The islands arc system of Andaman & Nicobar Islands situated in the Bay of Bengal is a major contributor to the overall high biodiversity figures of India. These islands are part of two global biodiversity hotspots and contain an impressive array of endemic flora and fauna. The herpetofauna of these islands have been the subject of explorations since the 19th century when European naturalists started natural history collections in these islands. However, our understanding of the terrestrial herpetofauna of these islands has been restricted to anecdotal observations, field records and taxonomic studies.. We conducted a four year survey of terrestrial herpetofauna in Andaman & Nicobar Islands. During this period 24 islands were surveyed for terrestrial herpetofauna. For the sake of completion, data from prior surveys and museum records were also compiled. We recorded 65 species of terrestrial reptiles and 17 species of amphibians from across the Andaman & Nicobar Islands. We present a presence absence matrix for all species recorded from various islands. As expected, the largest islands had the highest number of species and smaller islands within an island groups tended to have communities that were subsets of the larger island community. Several new records and some new species were discovered during our surveys. We found that the terrestrial herpetofauna in Andaman & Nicobar Islands occur in relatively high densities in undisturbed habitats, reaching as high as 3630 individuals per hectare in Little Andaman Island. Patterns in body size distributions were mostly right skewed, but inter taxa differences were observed in this. The shape of body size distribution did not change between Andaman Islands and Nicobar Islands. Distribution of body sizes within communities of co-existing species of frogs and lizards revealed a highly structured distribution, but not in the case of snakes. Species cooccurrence patterns showed inter taxa and inter island group differences. Differences in biogeographic and colonization histories of both groups of islands are suspected to be the reasons behind the observed species co-occurrence patterns. Abundance and geographic distribution patterns were less clearly defined for both frogs and lizards. We suspect that introduced species such as chital and Indian bullfrog might have adverse impacts on native herpetofauna in the Andaman & Nicobar Islands. We attempt a classification of island herpetofauna according to their vulnerability to extinction. We also assess the current conservation status according to the IUCN criteria and legal protection status according to WPA, 1972, and show that majority of species occurring in the Andaman & Nicobar Islands have not yet been assessed properly. We conclude this report by providing a checklist of the herpetofauna, other than turtles and crocodiles, of Andaman & Nicobar Islands.
  • No Thumbnail Available
    Item
    Status survey and conservation of the Himalayan salamander Tylototriton verrucosus in the Eastern Himalayas
    (Wildlife Institute of India, Dehradun, 2014) Vasudevan, K.; Kumar, R.S.; Sengupta, S.
    The Himalayan crocodile salamander Tylototriton verrucosus was first described in 1871 from the Nantin, Momien and Hotha valleys, in western Yunnan, China. Subsequently, there have been sporadic reports of the species from Nepal, Bhutan, India, Burma, China, Thailand and Vietnam. At present, the species is known to have a vast geographic distribution and thereby assigned as ‘Least Concern’ by the IUCN. This species shows considerable morphological overlap with 13 other known con-generics from the region, and is now considered to be a species complex. To predict the distribution of the species in India field surveys were conducted during the breeding period between May and August 2012 in parts of northern West Bengal State and northeast India. Along with the data from field surveys, historical data was compiled from published literature, Natural History Museum collections and from GBIF portal. Using ecological niche mapping tool – MAXENT 3.3.3k predictive modeling of the species distribution was done. For the analysis, 61 locations collected from field surveys in northern West Bengal and Manipur State, and 50 locations from archives were used. Fifty percent of the locations were used as training sites for the analysis. Using prior knowledge of the species a candidate set of 19 environmental layers (~1 km2 resolution) from WORLDCLIM 1.4 was used for the analysis. The variables were: precipitation, minimum and maximum temperature for six months, when the species is active during the year, and altitude. The predicted geographic distribution shows the salamander populations to occur in small, discrete sites in mountain ranges of South East Asia. It is hypothesized that historical factors to may have led to the observed pattern in its geographic distribution.