PhD Theses (SACON)
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Item Avifaunal Diversity of the Andaman Islands and their Conservation(SACON, 2010) Rajamannan, M.A.; Vijayan, LalithaBiodiversity hotspots in the world are chiefly tropical region is featuring high concentration of endemic species and has claimed ha lf of the world's terrestrial species, if all hotspot's are combined. These natural habitats are under threat now due to habitat loss and destruct ion. Consistently the islands, a small body of landmass are having a major role of its high endemism in the world. Nevertheless, the increasing demands on resources in the islands have resulted in their ecosystems being severely threatened and facing in its extreme habitat destruction. For example over 12.1 % of all bird species in the world are threatened with extinction today in which the majority of these are found in tropical forest and islands. There is disputing that global biodiversity is declining, but accurate measures are very hard to come by. Bird’s, the best known major group of organisms and just one component of biodiversity and far from the most significant in species numbers or biomass can help us to understand the problems and piece together the solutions, where the maintenance or restoration of the biological integrity of urban and Sundarbans areas must begin with a comprehensive study of the links between biota and land use. In this context bird communities are often used in investigations of habitat changes as the best indicators of the environment. Though the Indian mainland harbours rich avifauna diversity the Andaman and Nicobar Islands. The information on community structure and general bird ecology of these islands are little known and very few attempts have been made to study the bird community along their island distribution. Hence, the present study was initiated with the major objectives to: i) document the avifaunal diversity and status in different islands/vegetations, ii) observe the bird species distribution pattern in the Andaman Islands with their biogeographical importance, iii ) study the nested·subsets of the birds in different outer islands in terms of their presence/absence which will be providing a risk assessment of the extinction probability of the various species' populations isolated on the islands of fragmented habitat, and iv) understand the insular biology of the endemic and threatened species in Andaman Islands as of baseline information for their conservation.Item Status and Ecology of the Andaman Crake(SACON, 2009) Ezhilarasi, N.; Vijayan, LalithaAndaman Crake is a rare and endemic bird of Andaman Islands. There was no detailed information available on this species and was listed as data deficient till recently. Hence a study was undertaken during 2004-2007 to collect baseline data on the population, ecology and biology of the Andaman Crake. A variety of factors is responsible for Andaman Crake's habitat degradation and loss. In this chapter I briefly highlight key findings of this study, major threats to this species and suggestions for conservation and future research. While these threats and recommendations are given for the conservation of the Andaman Crake, they pertain to several other species ecologically dependent on the wet forests.Item Bird communities and their distribution pattern along the elevation gradient of Teesta Valley, Sikkim(SACON, 2008) Acharya, Bhoj Kumar; Vijayan, LalithaStudies on ecology of local communities are important for understanding environmental problems and planning area-based conservation management (Simberloff, 2004). Community composition, species richness and diversity of birds in five different elevation zones of Teesta valley, Sikkim were studied from June 2003 to March 2006 using point count sampling method. A total of 329 species of birds (299 during regular quantitative sampling and 30 during. opportunistic observations) belonging to 44 families was recorded in the Teesta valley during the study period. The study shows that Teesta valley harbors high diversity and abundance of birds. Broadleaved vegetation, situated at mid-elevation region, is the most diverse zone as compared to tropical, coniferous or alpine vegetation. Species accumulation curves based on number of point counts indicated that most of the species were detected in all the zones. Species richness (observed and estimated) was the maximum in zone II, whereas density, abundance and diversity were the maximum in zone iii. The species-abundance pattern of birds followed truncated log-normal distribution for total bird population as well as for all the zones except zone II which did not fit to any models. Bird data showed the presence of both types of species, exclusive (restricted to one elevation zone) and generalists (present in two or more zones), in the Teesta valley. Out of the total species observed (329), 156 (47.4%) were exclusively recorded in one specific elevation zone. Only three species, namely Blue Whistling Thrush, Greenish Warbler and White-capped Water Redstart occurred in all the five zones.Item Bird community structure along the altitudinal gradient in Silent Valley National Park, Western Ghats, India(SACON, 2008) Anoop Das, K.S.; Vijayan, LalithaMy research on bird community along the altitudinal-habitat gradients and their nest-site partitioning across habitats in Silent Valley National Park (SYNP) has portrayed several patterns. The work has explored some aspects of the processes which accounted for the patterns of variations in the community structure of birds in a pristine forest representative of the post Miocene and Pleistocene uplifted Western Ghats of India. In particular, the study addressed how altitude affected the distribution of birds and how the breeding birds shared their resources. The present study resulted in 5253 birds of 108 species, including 14 endemic species, from the 2314 point counts conducted in six habitats. The total number of species observed was 145 including opportunistic observations. Bird community structure of various habitats in corresponding altitudes varied significantly in terms of composition, abundance and diversity. The maximum species (59.2%) and individuals (27.2%) were in evergreen forest habitat and minimum in BLHF (22.8 % and 5.73% respectively). Shola habitats located at higher altitudes in the study area possessed higher species richness than mid-elevation broad leaved hill forest, which occurs within the altitudinal range of 1500- 1700 m. BLHF could be considered as a transitional zone between evergreen and shola forest. The significant difference in tree species richness of BLHF with adjacent EG and SHOLA habitats partly explain the reduction in number of bird species in this transitional zone.Item Status and Ecology of the Nilgiri Pipit in the Western Ghats.(SACON, 2007) Vinod, Uma J.; Vijayan, LalithaStudy was undertaken on the Nilgiri Pipit with the following main objectives a) determine the status b) unravel the ecology c) identify the key factors affecting the survival of the Nilgiri Pipit and suggest management optionsItem Status and ecology of the Nilgiri Wood Pigeon in the Western Ghats(SACON, 2006) Soumasunderam, S.; Vijayan, LalithaConservation of the species requires a comprehensive picture on the status and distribution, ecological requirements for feeding, breeding and other activities. Ecological studies on most of the endemics have not yet been conducted and hence, such information is not available for any management programmes. Moreover, human impacts on the habitats of most species are also not understood. Hence, the present study was conducted on an endemic, endangered species of the Western Ghats which is considered as Globally Threatened, the Nilgiri Wood Pigeon Columba elphinstonii, addressing mainly its biological and ecological requirements.Item Ecology of Bird Communities in the Anaikatty Hills, Coimbatore”(SACON, 2002) Nirmala, T; Vijayan, LalithaStructural and functional aspects of bird communities are believed to have direct relation with the structure of habitat and thereby act as indicators of environmental changes. Various components such as the type of resource, quantity of resource and spatial and temporal distribution of resources play a major role in determining the community structure. In general, the central theme in the functional aspects of the avian community studies has been, how the available resources for biological activities such as foraging, roosting and nesting are partitioned among the existing group of species. Studies on bird community in different habitats are very few in India, and the pattern and processes of a group of species or an individual species were studied separately. The study of birds in relation to habitats will give valuable data for forest management. Area outside protected area network is also equally important for birds and biodiversity conservation. This study was designed to determine the ecology of the bird communities in the mixed dry deciduous forest and scrub forest (SACON) in Anaikatty Reserve Forest, foothills of Nilgiri Biosphere Reserve, Coimbatore, South India.Item BIRD COMMUNITIES OF THE THORN AND DRY DECIDUOUS FORESTS IN MUDUMALAI WILDLIFE SANCTUARY, SOUTH INDIA(SACON, 1998) Gokula, V; Vijayan, LalithaBirds are important components of forest ecosystem, playing a major role as pollinators, consumers and dispersers of plant seeds, and predators of insects. In nature different species form intricate assemblages as a result of the local ecological make up. Whittaker (1975) states that communities are assemblages of populations of species which occur together in space and time. Studies on bird community ecology starting from MacArthur and MacArthur(1961) have attracted wide attention. The main focus of community ecology is the manner in which groupings of species are formed and distributed in nature and the ways in which these can be influenced or caused by interactions between or among the species and the physical and biological factors of their environment. The cause-effect relation of such assemblages led to an increased interest in studies on bird communities (Cody, 1974; Cody and Diamond, 1975). An understanding of the determinants of bird community structure is extremely important for the practical development of guidelines for the habitat management