Theses and Dissertations

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Subject: search.filters.subject.Nest site selection

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    Nest site selection in Pallas’s Fish-eagle and nesting behaviour in the Rajaji-Corbett landscape
    (Wildlife Institute of India, Dehradun, 2024) Tangaria, Abhishek; Jha, Ashish; Pandav, Bivash; Kumar, R.S.
    This study investigates the nest site selection and nesting behavior of Pallas's Fish-eagle (PFE) across the sub-Himalayan tract in India, addressing a significant knowledge gap in the species' natural history. PFE, classified as Endangered globally and of high conservation concern nationally, exhibits unique nesting preferences and ecological requirements. Prior research, including studies from Bhutan and Bangladesh, has highlighted the species' preference for unobstructed nest trees and proximity to water sources and human settlements. However, comprehensive data from India remains limited. The study aims to explore factors influencing PFE's nest site selection, such as habitat quality, microclimate, food availability, and protection from predators and human disturbance. Additionally, it seeks to document the species' reproductive behavior, including hatchling development, parental duties, and nest predation pressures. Surveys covered segments of the Ganga, Kohlu, Kho, Palain, Mandal, Asan Barrage, Dakpatthar Barrage, and Ramganga, recording data on sightings and nest characteristics. A total of twelve nests were found, with only one destroyed by a storm. The majority of nests were built on Bombax ceiba and Shorea robusta trees, with an average height of 29.9m and GBH of 473cm. Behavioral observations were conducted at three accessible nests, monitoring parental presence, predator interactions, and nest guarding behavior. Spatial analysis in ArcGIS Pro considered various land cover types and environmental factors, finding that barren land and rangeland significantly influenced nest site selection. Euclidean distances to different land cover types and elevation were also key factors. Statistical analyses using R revealed correlations between tree height and nest height, and generalized linear models highlighted the impact of land cover and environmental variables on nest presence. Nest trees were typically tall and robust, with Bombax ceiba and Shorea robusta being the most commonly used species. These trees provided unobstructed branches and greater accessibility. The study also highlighted the importance of open land around the nest tree, aiding in vigilance and territory defense. At a macro scale, the presence of barren land and flooded regions positively influenced nest site selection, while slope and distance from rangeland showed negative correlations. Behavioral observations at three nests revealed high predation pressure, particularly from crows, and kites. The presence of human settlements increased predation incidents, affecting parental investment in nest defense.
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    Nest Site Selection and Effects of Anthropogenic Changes to the Rushikulya Nesting Beah, Orissa on Olive Ridley Sea Turtes
    (Wildlife Institute of India, Dehradun, 2009) Muralidharan, M.; Sivakumar, K.; Choudhury, B.C.
    The Olive Ridley sea turtle Lepidochelys olivacea is known to nest both sporadically and in arribada's in the Indian coastline. Of the three mass nesting sites on the Orissa coast, the Rushikulya rookery has been considered as a key factor in maintaining the future populations of the Ridley's in the Indian coast. Though several studies have been carried out on various ecological aspects of the species along the Orissa coast this study looked into a finer scale of behavioural patterns exhibited by the females while selecting the nesting sites. Other aspects that are looked into in detail in this study included the various impacts of anthropogenic activities near the nesting habitat of the turtles including the impact of nest predators. The observed sporadic nesting turtles crawled an average of 47.39 m from the waterline before nesting (Range = 10.7(102m, SD = 21.0481, n = 70). Tests were conducted to check for the possibility of whether turtles were actively choosing their site of oviposition while compared to random placement over varying distances. Beach slope and soil temperature were not found to be significantly different from the nesting sites (Slope - F = 1.289, . Temperature - F = 2.241, df = 8 P>0.05) while compared to sites along the track of the nesting turtles, whereas pH and moisture were found to be significantly different from the nest-site to all sites prior to them (pH - F=37.640, Moisture - F = 44.208, df = 8 P<0.05). This shows the possibility of both pH and slope to be amongst the possible proximate cues used by a turtle in deciding a final nest. The effects of beach lighting on the disorientation of turtle hatchlings at this site has already been studied at various levels and this study re-affirms the results of the previous studies by including the effects of lighting acting upon various distances away from the water-line as well as different photic conditions present along the beach and from the adjoining villages. With areas near the villages showing maximum disorientation while compared to areas shielded from light by Casuarina plantations. Associated human activities near the Rushikulya rookery could also act in supporting and maintaining populations of certain animals (feral dogs, jackals), which have had an increased threat to turtle nests. The plantation of Casuarina adjoining the nesting beaches could also act in providing refuge to such predators apart from the known effect of changing the geomorphologic profile of the beach. These predators are known to be able to thrive even in marginalized habitats sustaining their numbers near human occupied areas. These plantations may thus also be aiding an artificial boom in their numbers thus having an increased impact of their predation on turtle nest while compared to natural levels ·of predation loss. A Passive Tracking Index (PTI) for the predator presence and activity observed a minimum presence before the mass nesting which increased immediately after the commencement of the mass nesting. Protective chain link fencing laid across sections of the beach flanked by Casurina to reduce the predator pressure in these areas may not have proven to be completely successful as high activity was still observed in the weeks following the mass nesting.