PhD Theses (SACON)
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Item Assemblage of Shorebirds in the Sindhudurg District Maharashtra(SACON, 2022) Babu Rao, Golusu; Babu, SMigratory shorebirds are the most threatened waterbird species around the world. Shorebirds in India have received little attention, particularly on the west coast. Thus, this study was conducted in the coastal areas of the Sindhudurg district, Maharashtra. The coastal habitats in the district are dominated by beaches, mudflats, and mangroves, which have been identified as potential habitats for shorebirds. Thus, the distribution, abundance, and factors influencing habitat use of shorebirds were studied from these three habitats across seven sites and five seasons. Among the three habitat types, mudflat was an important area for shorebirds thus fine-scale habitat selection for select shorebird species was carried out in the mudflats. Total count and photographic methods were used to count the birds. A total of 36 species of shorebirds were recorded, of which 21 and 10 species used Sindhudurg coast as stopover and wintering sites respectively. Mudflats had a higher species richness (21) than the beach (20) and mangroves (14) habitats. Plovers were the most common and abundant species in the study area. nMDs showed various pattern of shorebird species composition across the habitats and seasons. The cluster analysis revealed five distinct migratory seasons in shorebirds along the Sindhudurg coast: 1) arrival phase, 2) wintering phase, 3) early departure and late arrival phase, 4) departure phase, and e) breeding phase. The physiochemical parameters of water and prey varied significantly between habitats and seasons. Salinity showed decreasing trend from beach (34.67±5.94) towards the mangroves (28.07±7.66). Prey abundance was higher in mudflats and during the wintering season. BIO-ENV analysis showed that among the measured environmental parameters salinity was the key factor influenced prey distribution (ρ=0.51). The shorebird richness (X2=56.5, P=0.00) and abundance (X2=32.6, P=0.00) positively influenced by crustacean density, salinity and bivalve density. Prey availability and accessibility had a major impact on the finescale habitat selection of the studied species. The Lesser Sand Plover and Kentish Plover avoided areas with oyster beds and preferred fine sand substrates with higher crab densities. Eurasian Curlew selected high profitable foraging sites close to the waterline with increased surface penetrabilityItem OCCUPANCY AND DISTRIBUTION PATTERN OF OWLS IN ANDAMAN ISLANDS WITH SPECIAL REFERENCE TO COMMUNITY ASSEMBLY RULES(SACON, 2021) Marimuthu, S Suresh; Babu, SThere is a laxity of knowledge in taxonomically well recognized species, which did not gain adequate attention from conservation biologists and are prone to extinction. Owls are one of such avian nocturnal predators. Due to their nocturnal and conspicuous behaviour many of the avian community studies neglecting owls to incorporate in them. Considering these facts, studies on owl species ecology is prerequisite for the conservation. So, this thesis is an attempt to develop such base line information on owls with two broad objectives: (1) to assess the relative abundance and occupancy of owls in the Andaman Islands and (2) to evaluate various species assembly rules in offshore islands using owls as model organism. To achieve these objectives, I did a survey with an aim to elucidate the environmental gradients (such as land-cover types, logging intensity) that influence the distribution and abundance of owls in the Andaman Islands. In addition, I also assessed the perception of local people about owls and effect of human activities on roosting owls using experimental and evidence-based study. I also employed Hierarchical multi-scale sampling strategy to estimate large-scale (sampling unit level - Ψ) and small-scale (survey station level - θ) occupancy using multi-detection methods (p). I modelled the occurrence of each species of owls as a function of island characteristics using the presence-absence of owls and a set of abiotic and biotic variables of 73 offshore islands. Finally, dispersal-driven assembly rules of the five owl species were tested with the same offshore islands surveyed. EcoSim v. 7.0 was used to test the Diamond’s assembly rules (1st, 2nd and 5th rules) using two statistical indices viz., C-score and number of unique species combinations. NeD and Nestedness Temperature Calculator were used to test nestedness. Overall, this study provided first-hand information about the owls’ distribution, their threat, ecological requirements, and the dispersal patterns in Andaman archipelago. It also helped to identify the critical island characteristics to ensure the avian population. The continued alteration of evergreen forests, extraction of minor products (for example: cane) and logging associated understory clearings might bring these endemic species’ survival to an end.