PhD Theses (SACON)

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End date: 2009Subject: search.filters.subject.Mammals

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    Communities of small mammals and small carnivores in the Teesta River Basin, Sikkim Himalaya, India
    (SACON, 2008) Thapa, Jaya; Bhupathy, S.
    Differences in communities of plants and animals along environmental gradients have been the basis for many ecological theories. Among the first geographical patterns to be recognized in ecology was the climatic gradient in body size of animals, later formalized as the Bergmann 's rule. Latitudinal and altitudinal gradients in species richness are other geographical patterns that have long since been recognized. The different nature of gradients and the ecological factors that cause such gradients have both been subjects of considerable debate in recent decades. Community structure in animals can also be influenced by various factors such as vegetation, biological constraints and historical factors, which may not form gradients. In this dissertation I have examined the in fluence of altitude and vegetation on communities of small mammals and small carnivores in the 11 Himalayan mountain ranges in the Indian State of Sikkim. The sharp altitudinal gradient from 230 m to 8586 m and the variety of vegetation types in this small state,. The overall goal of this study was to examine the influence of altitude and vegetation on the organizalion of the small mammal community in Sikkim Himalaya, with respect to its species richness, composition. distribution, and abundance. The specific objectives of this study were: a. To test the hypothesis that the body weight of murid rodents and shrews should respond to the sharp altitudinal gradient; b. To identify the pattern of variation in the community structure of the murid rodents and shrews along an altitudinal gradient and among different vegetation types; c. To test the hypothesis that murids and shrews differ in microhabitat use in a manner that is consistent between vegetation types; and d. To examine the influence of altitude and vegetation types on the composition and relative abundance of the small carnivore community, as well as their diet. This study was carried out in the North and South Districts of Sikkim in the Teesta River Basin, between 230 m to 3700 m altitude, from June 2003 to April 2004 and from May 2005 to December 2005
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    IMPACTS OP HABITAT FRAGMENTATION ON THE TERRESTRIAL SMALL MAMMAL COMMUNITIES IN THE TROPICAL RAIN FOREST OP THE ANAIMALAI HILLS IN THE WESTERN GHATS, SOUTH INDIA
    (SACON, 1998) Prabhakar, A; Kumar, Ajith
    The loss and fragmentation of the species-rich tropical rain forests is the most serious conservation crisis currently facing us. In the Western Ghats in south India as much as 40% of the forests was lost between 1920s and 1990s, with a 17-fold increase in forest patches. Such fragmentation of forests leads in the long run to loss of species due to the problems faced by small isolated populations, the cascading effects of the changes in the micro and macro climate, and the effects of invading species. The goal of this study was to make an assessment of the changes in the small mammal community due to the fragmentation of their rain forest habitat in the Western Ghats. The study animals included rodents of the Families Muridae and Muscardinidae, and shrews of the Order Insectivora. The specific objectives were: (a) to evaluate the differences among rain forest fragments in the community structure of small mammals, in relation to macrohabitat features of the forest fragments; (b) to examine the synchrony among forest fragments in the seasonal variation of several demographic parameters; and (c) to identify species differences in microhabitat preferences and examine their relevance to the changes in community structure due to habitat fragmentation.
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    IMPACTS OF HABITAT FRAGMENTATION ON THE ARBOREAL MAMMALS IN THE WET EVERGREEN FORESTS OF THE ANAMALAI HILLS IN THE WESTERN GHATS, SOUTH INDIA
    (SACON, 1998) Umapathay, G; Kumar, Ajith
    Habitat fragmentation is the most severe threat to biological diversity and is the primary cause of the present species extinction crisis. Small populations in fragments are highly prone to extinction due to demographic and evironmental stochasticity, disease and catastrophes. Long term degeneration of habitat might also add to this extinction. In south India, wet evergreen (or rain) forest is confined to the Western Ghats mountains. Human activities such as plantations of tea, coffee, teak, etc., and construction of roads, railways, and reservoirs during the last two centuries have led to extensive loss of these forests. More importantly, the remaining forest has been severely fragmented. The impact of forest fragmentation is expected to be particularly severe among the arboreal mammals due to loss of arboreal connectivity between forest fragments. In this background, the objectives of this study were; 1) To assess the extent to which arboreal mammals disappear from wet evergreen forest fragments with respect to various landscape and habitat parameters associated with forest fragmentation; 2) To identify changes in their activity pattern and feeding ecology; 3) To examine changes in demographic parameters of these species in relation to habitat fragmentation; and 4) To examine species differences in their response to forest fragmentation and to suggest appropriate measures to enhance the survival of arboreal mammals in forest fragments.