Theses and Dissertations

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    POPULATION AND RESOURCE UTILISATION BY REPTILES IN UPPER NILGIRIS, NILGIRI BIOSPHERE RESERVE, WESTERN GHATS, INDIA
    (SACON, 2005) ARMSTRONG, A. MATHEWS NIXON; Bhupathy, S
    Herpetofauna (reptiles and amphibians) are important components of both terrestrial and wetland ecosystems as they play a major role in energy flow and nutrient cycling. Both of them are also excellent indicators of environmental degradation. Being poikilotherms, reptiles tend to partition time and space more often than homeotherms as their physiology and behaviour are closely linked to environmental conditions. However, quantitative data on the population and resource use by reptiles are scanty in India. Resource use can be studied with respect to the three most often recognized niche axes: spatial (habitat use), temporal (activity period) and trophic (food). Herpetofauna of India, one of the most diverse taxa, is poorly known regarding their ecology and population characteristics. Major objectives of this study was to (1) assess the population status of reptiles and factors determining their distribution in various habitats of Upper Nilgiri plateau (2) determine the habitat use and food habits of reptiles, and (3) to understand the resource use at spatio-temporal and trophic levels by reptiles in Upper Nilgiris.
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    Evaluating the Impact of Introduced Spotted Deer (Axis axis) on Forest Floor Herpetofauna of Andaman Islands
    (Wildlife Institute of India, Dehradun, 2013) Mohnty, Nitya Prakash; Vasudevan, K.; Sivakumar, K.
    It is common knowledge that organism in an ecosystem, are connected to each other through trophic levels. Even though the importance of interactions among trophic levels is well established in theory, demonstration of such interactions is not always easy. Over the years, studies that focus on the trophic interactions among starkly different taxonomic groups have come to the fore. These studies have furthered our understanding of ecosystems by demonstrating relationships between trophic levels so apart, the connection among which may not be apparent at first. Along these lines, the situation of introduced spotted deer in the Andaman Islands presented an ideal opportunity to understand the potential effect of a mammalian invasive herbivore on native, insectivorous forest floor herpetofauna. I hypothesised that herbivory is likely to depress folivorous arthropod abundance, which in turn may lead to a decline of insectivorous forest floor herpetofauna. Additionally, reduction in vegetation cover may render the habitat unsuitable for herpetofauna and make them vulnerable to predation. The objectives of this study were to evaluate the effect of chital on the forest floor herpetofaunal abundance and to determine the pathway of interaction between them. A contrasting effect of herbivory by chital on reptiles and on amphibians in the Andaman Islands was observed during the dry season. Forest floor reptiles, which included agamids, geckos and skinks showed reduced abundance in the presence of chital in comparison to an island where chital was absent. This effect of chital on reptiles was found to be mediated by vegetation cover. Chital significantly reduced the vegetation cover below their maximum browse height (1.5 m) in the Islands and which in turn led to a reduction in reptile abundance. Although, it was not clear if any of the observed species was benefitted in the presence of chital, the semi-arboreal Coryphophylax subcristatus appeared to be affected. Amphibian abundance on the other hand seemed to be unaffected by the use of the habitat by chital. Litter arthropods influenced the densities of amphibians the most. This study brought to light a pathway of indirect interaction between a mammalian herbivore and insectivorous herpetofauna. In doing so it raised conservation concern about the capability of an introduced species to alter an island ecosystem drastically and acutely impact several endemic fauna.
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    Effect of Habitat Alteration On Herpetofaunal Assemblages on Evergreen Forest in Mizoram, North-East India
    (Wildlife Institute of India, Dehradun, 1999) Choudhury, B.C.; Panwar, Samraat; Rawat, G.S.
    The response of frogs and Lizards to habitat alteration was studied in South Mizoram. Chronoseres were selected such that two successional gradient were represented- jhum fallows regenerating to mature forest. and jhum allows converted to teak plantations. Herpetofauna were sampled by three techniques- strip transects, pitfall trapping. and systematic searching. Species richness of herpetofauna increased along the jhum-mature forest gradient. However. teak plantation had a depauperate herpetofauna. similar in composition to the 1- year jhul1l fallows. All frogs and lizards were c1assilied into 6 guilds on the basis of their activity period (diurnal or nocturnal) along with whether they were terrestrial , arboreoterrestrial or arboreal. Analysis of the strip-transect data showed that there were distinct differences in the distribution and abundance patterns of diurnal and nocturnal species. To examine patterns, multidimensional scaling (MDS) was used for indirect gradient analysis in two ways- firstly to summarize differences between sites and secondly, to explore possible associations between herpetofaunal guilds and habitat parameters across categories. The MDS differentiated two different groups of habitat variables. One group makes up the gross structural components of the habitats. while the other represents microhabitat parameters. All guilds were more strongly associated with trends in microhabitat distribution. than macrohabitat-parameters. while species richness showed diffuse associations with habitat parameters. The assemblages in the I to 10 yr. jhum fallows and teak plantations were dominated by a set of terrestrial and arboreo-terrestrial lizard species. Most of those species are distributed widely. either in the Indian subcontinent. or further east and south. into South-east Asia. On the other hand. a number of frogs and some lizards were restricted to mature forest. Most of these species are restricted either to North-east India. or to the study area itself. and some are apparently hitherto undescribed species. The fact that so many narrowly distributed species were found in mature forest has obvious conservation implications. Overall. the results suggest that in a mosaic of habitats resulting from jhum-cultivation. even remnants of primary forest may be of immense importance for persistence and recolonization by mature forest herpetofauna. Teak plantations offer a very marginal habitat for a large set of herpetofauna. even after a long period of growth.