M Sc Dissertation(WII)

Permanent URI for this collectionhttp://192.168.202.180:4000/handle/123456789/3

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Start date: 2021Subject: search.filters.subject.Birds

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    Effects of Local- and Landscape-level Drivers in Influencing Bird Diversity and Persistence in Cashew Plantations of the Northern Western Ghats
    (Wildlife Institute of India, Dehradun, 2024) Madhu, Nandita; Jayapal, Rajah; Page, Navendu V.; Naniwadekar, Rohit
    Agricultural expansion is a significant driver of deforestation and biodiversity loss, particularly in the tropics. The Western Ghats-Sri Lanka biodiversity hotspot is no exception. Most forest patches in the northern Western Ghats are being cleared for cashew cultivation. However, here, cashew plantations host varying proportions of cashew and native trees and have varying extents of ambient forest cover. Investigating the effects of such local and landscape-level drivers across land use types on taxonomic, functional, and phylogenetic diversities, as well as species- and trait-specific responses of birds, as implemented in this study, can give comprehensive insights on the impacts of forest conversion. I conducted this study in the low-elevation forests and cashew plantation landscape of Tillari, Maharashtra. I compared tree species diversity and vegetation structural attributes across land use types using Hill-Shannon diversity and linear models (LMs). To assess how land use type affects bird species composition and taxonomic diversity, I used non-metric multidimensional sampling (NMDS) and Hill-Shannon diversity. To compare functional and phylogenetic impacts across land use types, I used SES (Standardised Effect Size) values of fMPD (functional Mean Pairwise Distance) and pMPD (phylogenetic Mean Pairwise Distance) for LMs and Tukey’s post-hoc analysis. Using Hierarchical Modelling of Species Communities (HMSC), I looked for 1) bird species responses, 2) trait responses, and 3) a phylogenetic signal in the residuals. I collected bird and vegetation data from 100 points distributed across forest, mixed cashew plantations, and pure cashew plantations. My field collaborator (Vishal Sadekar) and I sampled vegetation within a 10 m radius of circular plots around all points. We sampled birds, implementing 10-minute point counts at a point, replicated 5 times across 4 months between January to May 2024. Vegetation differed significantly across all three land use types in terms of tree species diversity and tree height, where the forest had the highest estimates followed by mixed cashew. NMDS showed that the community in mixed cashew plantations overlapped with that of pure cashew plantations. There was no significant effect of land use type on functional diversity. But taxonomic and phylogenetic diversities were lowest in pure cashew. The HMSC model revealed a low explained variation (Tjur R2 = 0.1372), but I found land use type, a site-level variable, to exhibit the highest explained variation of 58% compared to the landscape-level variables. Forest species like Malabar Trogon (Harpactes fasciatus) and Black-naped Monarch (Hypothymis azurea) responded negatively to mixed and pure cashew plantations. Species like Golden-fronted Leafbird (Chloropsis auriforns) and Tickell’s Blue Flycatcher (Cyornis tickelliae) benefitted from mixed cashew and open country species like Indian Peafowl (Pavo cristatus) and Plain Prinia (Prinia inornata) responded positively to pure cashew. Trait response analysis revealed that evergreen species responded positively to the forest and negatively to both cashew habitats. Sedentary species responded positively to forest cover in 800 m. No evidence of a phylogenetic signal was found in the residuals (⍴ = 0.23, 95% CI: 0 - 0.68). This study highlights the value of mixed cashew plantations which are more habitable than pure cashew plantations due to native tree prevalence. However, this study also emphasises that even mixed cashew plantations cannot replace forests as habitats for evergreen forest species. This message is now more crucial than ever in the light of ongoing forest clearance in the northern Western Ghats.
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    Leveraging citizen science for bird monitoring: A case study assessing the impacts of urbanization on bird assemblages of the Nilgiris
    (Wildlife Institute of India, Dehradun, 2024) Phinehas N, David; Kher, Varun; Robin, V.V.; Jha, Ashish
    Anthropogenic alteration of habitats is the leading cause for biodiversity loss across the world. To accommodate the ever increasing human population, intensification of urbanised areas have led to the most extreme forms for habitat alteration (Batáry et al., 2018) and imposes a unique set of ecological filters. 2. Over that last 2 centuries during the colonial past, the Nilgiris has witnessed large-scale change in the landscape structure from native shola-grassland matrix to extensive tea and eucalyptus plantations. Currently it has emerged into a tourist haven, attracting millions every year, leading to expansion of the urban cover to accommodate the growing demand. 3. This study illuminates the profound effects of urbanization on bird communities in the Nilgiris, showcasing how habitat transformation alters community parameters such as, species richness, abundance, and composition. My results indicate a stark pattern: as urbanization intensifies, species richness declines, while a select few generalist species thrive in high abundance. 4. My findings reveal that settlements and proximity to remnant shola patches are the primary factors influencing avian community structure. Areas with higher settlement percentages and greater distances from shola patches exhibit reduced species richness and diversity. In contrast, less urbanized areas, closer to natural habitats, maintain higher biodiversity. This aligns with the hypothesis that urban environments simplify habitat structures, creating 'filter' that only a limited number of species can pass through, thereby fostering biotic homogenization. 5. Urban generalists, such as the House Sparrow, Rock Pigeon, and House Crow, flourish in highly urbanized zones due to their ability to exploit the abundant food resources and nesting sites provided by human activities. These species benefit from the homogenized urban landscape, which offers ample opportunities for foraging and nesting, often at the expense of more specialized species. Conversely, endemic shola forest specialists, such as the Nilgiri Laughing thrush and the Black-and-orange Flycatcher, suffer due to their stringent habitat requirements and limited dispersal abilities. These findings highlight the ecological trade-offs imposed by urbanization, where habitat degradation and loss disproportionately impact species with narrow niche widths. 6. This study also highlights the usefulness of citizen science as a tool for collection of largescale data in a short time span. I also tested for the accuracy of the citizen science data against a research-grade benchmark, ie, data collected by me. The results suggest that no significant variations were detected between the two datasets. 7. Conservation Implications: Monitoring species with vulnerable traits to keep track of further degradation of the habitat and involvement of the local citizens is needed. The study highlights a critical need to preserve remaining shola fragments and implementation of biodiversity friendly urban planning.
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    The effect of disturbance-induced changes in vegetation structure and arthropod abundance on mixed-species bird flocks in the oak forests of the Western Himalaya
    (Wildlife Institute of India, Dehradun, 2024) Satish, Aditya; Page, Navendu; Bangal, Priti; Shahabuddin, Ghazala
    Mixed-species flocks are an interactive group of insectivorous birds that forage together and move in the same direction. Flocks provide foraging and anti-predatory benefits to participants. Habitat disturbance may affect flocks by – a) altering presence or abundance of participating birds in the community or b) altering flocking propensities of species. 2. I investigated the effects of habitat disturbance on flocks in the Western Himalaya of Uttarakhand, India. Disturbance was mediated through two mechanisms – changes in vegetation structure and arthropod abundance (food availability). I examined how these environmental variations impacted flocks at a community level through changes in flock richness, flock size, number of flocks encountered and flock composition. I also explored how flocking propensity (a species-specific tendency to join flocks) is impacted by these variables. 3. Flocks are a subset of the insectivorous bird community. I found that insectivore richness and abundance decreased with reduced structural complexity of vegetation caused by disturbance. Reduced structural complexity also led to a corresponding decline in flock richness, size and number of flocks encountered in disturbed sites. With regards to variation of flock composition with disturbance, I found no clear species-composition-based clustering in transects with similar disturbance levels. 4. There seems to be an interactive link between arthropods, insectivorous birds and disturbance. Disturbance was correlated with strong declines in foliage arthropod abundance, which in turn contributes to lower insectivore richness and abundance. Flying arthropod abundance largely remained constant with disturbance, so I would like to draw 2 attention to the effect of foliage arthropod abundance on flock variables in the following sections. 5. The number of flocks encountered increased with foliage arthropod abundance. Since insectivores in undisturbed sites are supported by a larger prey base, the higher frequency of flocking may be correlated to the larger pool of insectivores that are available to flock at a given time. I did not find significant effects of foliage arthropod abundance on flock richness and flock size. 6. I found that flocking propensity of the three most common species (Gray-hooded Warbler, Black-throated Tit and Green-backed Tit) in flocks showed a declining trend with higher disturbance. I also observed that the propensity of these species showed an increasing trend with higher foliage arthropod abundance. However, none of these relationships were statistically significant. More detailed research is recommended to investigate these preliminary patterns further, to better understand the complex interactions between propensity, disturbance and food availability. 7. To conclude, disturbance was found to have a negative impact on mixed-species flocks, primarily by altering the presence and abundance of insectivorous birds. From a habitat perspective, insectivores suffered declines due to the simplification of vegetation structure. Insectivores also face food scarcity as foliage arthropod abundance decreases. The combined effect of habitat loss and reduced food availability in disturbed sites leads to lower insectivore richness and abundance, which is in turn reflected in fewer, smaller and more species-poor flocks.
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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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    Study of Some Important Aspects of Breeding Ecology and Vocalization of Jungle Prinia in Siswan Community Reserve Punjab India
    (Wildlife Institute of India, Dehradun, 2021) Chandra, Vignesh M.; Mohan, D.; Singh, Pratap
    Several groups of songbirds including North-American wood warblers belonging to the genus Vermivora, Parula, Dendroica, and Setophaga have developed two singing modes or categories of songs which are having different functions. Among Indian breeding birds Jungle Prinia along with three Phylloscopus warblers (humei, pulcher, and chloronotus) are known to have two singing modes. To find out function of two singing modes by the bird during different stages of breeding in Jungle Prinia, I studied the use of two singing modes of Jungle Prinia and its relation with its habitat or vegetation. My study suggests that the singing mode A is related to aggressive mal-male interactions and singing mode B is linger distance signal and has role in male and female interactions. Bird density was found to be positively related to the differential singing mode B use.
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    Species interactions with in mixed species bird flocks along an Elevational gradient in the Western Himalaya.
    (Wildlife Institute of India, Dehradun, 2021) Gokhale, Pranav; Kumar, R.S.; Mohan, D.
    Mixed-species bird flocks (hereafter, “flocks”) are an interactive community of largely insectivorous birds, which move and forage together to gain enhanced access to resources and protection from predation. In this study, I aimed to investigate a question: do interspecific interactions within mixed-species flocks change along an elevational gradient? To test this, I carried out this study in the Garhwal region of the Western Himalaya in Dehradun District, Uttarakhand from January to April 2021 (spanned across two seasons). The study areas comprised of three field sites along an elevation gradient from western part of the Rajaji Tiger Reserve (300 m ASL) to Mussoorie (2200 m ASL). I sampled flocks and relative abundances of birds on the two pre-existing trails in each of the three field sites. I walked each trail 10 to 13 times. I recorded species identity, group/cluster size of all birds seen inside as well as outside flocks on the trail and within 10 m on either side of the trail. I assessed arthropod prey availability in winter for the flocking species by using branch bagging technique on the same trails. In total, I clipped 150 branches for the three elevations. I calculated species-specific flocking propensity for each elevation from the information on birds seen within and outside flocks. I used network density (potentially realised associations) and weighted degree (associated strength) to quantify the interspecific interactions (associations) within flocks. To control for the influence of species availability on flock network properties, I generated null flocks using an abundance-based null model. I recorded 80 flocking species in 412 flocks, of which, 179 flocks were observed at the High elevation, 156 at the Mid elevation and 77 at the Low elevation. Majority of species in the Western Himalayan flocks were insectivorous gleaner. I found insect prey availability (resource) to decrease with increasing elevation in winter. As expected, flocking propensity, network density and weighted degree increased with elevation in both seasons indicating greater potentially realised associations and high strength of associations between species. Interestingly, the Low elevation flocks disintegrated completely at the onset of summer possibly due to the greater availability of resources, or an upward migration of species for breeding. I did not analyse the Low elevation flocks in summer due to small sample size (n=5). Flocking propensity and network density decreased from winter to summer at Mid and High elevation while, weighted degrees decreased only for the Mid elevation. This is likely that true summer may not have started at the High elevation during the course of my fieldwork. To conclude, with increasing elevation in both seasons, species not just flocked more, but associated with many species and these associations became stronger, potentially due to the scarcity of resources. It is possible that species may not be able to access resources efficiently when foraging on their own at the High elevation, compelling them to participate in flocks to avail complementary benefits from many other species.
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    Making the Urban Matrix Matter : Characteristics of the Avifaunal Community of the Urban Matrix Relative to the Urban Green Spaces of Dehradun
    (Wildlife Institute of India, Dehradun, 2021) Coutinho, Jason Bismarck; Onial, Malvika; Kaushik, Monika
    Urban ecology is a field in science which deals with understanding the ecological synergies within urban systems. This is a relatively new field which started out when ecologists recognized the importance of quantifying human impacts on ecosystems globally. This field is ever so pertinent now that no ecosystem remains which doesn’t have human induced changes. 2. Urban ecosystems are dynamic ecosystems with interactions similar to those of natural ecosystems, but they are also directly influenced by the culture, politics, economics and social organization of human society. Urban has different definitions all over the world with no single consensus and such disparities make it impossible to compare ‘what is urban’ across the globe. Simply urban areas are cities and suburban areas with the landscape being called as the ‘built environment’. Urbanization and the urban sprawl have impacted not only the land covers across an urban area, but also the biodiversity in it. This urbanization filters the biological community at various levels and it is pertinent that we understand this filtering. 3. The urban landscape can be divided into two major categories for simplicity. The urban green spaces are terrestrial areas, both public and private covered with vegetation, made available to users. These are very important to the health of the city. They enhance the wellbeing of the people in the city and also are habitats for urban wildlife. The urban grey on the other hand is the ‘built’ or ‘artificial’ environment. This is usually seen increasing as we reach the center of a city or urban area. 4. The urban matrix is a mix of the greens and the grey and has no clear definition. It is all the habitat patches in the urban landscape that lie outside the urban green spaces. This urban matrix is highly dynamic and every urban area has its own unique habitat mosaic. This important matrix however has not been studied extensively. In most areas of urban ecological research, the matrix’s relevance is undervalued. The current study was conducted in the city of Dehradun from March 2021 to April 2021. To understand the importance of the urban matrix’s contribution in maintaining an urban areas biological diversity, this study aims to quantify the avifaunal community in the urban matrix. Further it looks to understand the relevance of the avifaunal assemblage characteristics of the urban matrix relative to that of the urban green spaces. 5. To study this, the patterns of the avifaunal community in Dehradun were explored. Fundamental properties of biological communities like species richness, abundance, density and composition were looked at the habitat scale. At the landscape scale, potential habitat correlates of the species richness and density were studied so as to shed some light on the factors and processes that might be driving the community assembly in the urban matrix. The comparison of the avifaunal assemblage was done by comparing the overall richness, density and composition in the urban matrix and urban green spaces. 6. In the urban matrix, 109 sampling units were laid and then sampled using a variable radius point count method. A total of 3775 individuals belonging to 81 species were recorded. Feral Pigeon was the most dominant species, habitat-wise species richness was maximum in the built – up areas (54 species) and species density was maximum in scrublands (13.12mean ± 4.35SD per hectare). Ordination graphs showed that plots of green cover were dissimilar from the other habitats. The species richness in the urban matrix was positively influenced by the increasing proportions of open areas and scrublands. Built – up had negative influence on the species richness but showed peaking at moderate levels of human development. Density in the matrix was positively influenced by increasing proportion of scrublands and the landscape heterogeneity. It was negatively influenced by increasing proportions of built – up and green cover. Comparisons of the richness and density of the urban matrix and urban green spaces showed that there was a huge difference in both the parameters, with urban green spaces showing higher values for both. The species composition Venn diagram showed that the matrix and urban green spaces share 64 species among them, with the urban green spaces and urban matrix showing 50 and 17 unique species respectively. 7. In general, the current study shows the relative importance of the urban matrix in maintaining the urban biodiversity and the need of conserving the habitats in the matrix to boost the urban biodiversity.