Theses and Dissertations
Permanent URI for this communityhttp://192.168.202.180:4000/handle/123456789/1
Browse
312 results
Search Results
Item Influence of Canopy Gaps on Mangrove vegetation and Crab communities in the Andaman Islands(Wildlife Institute of India, Dehradun, 2025) Sengannan, Perarivalan; Prabhakar, N.Small-scale, infrequent disturbances enhance habitat heterogeneity in the landscape and promote diversity. Canopy disturbances caused by lightning strikes in mature mangrove stands modify environmental factors such as canopy cover and light intensity. Response of mangrove vegetation and crab communities to such canopy gap formation remains the least investigated aspect among ecologists. The canopy gaps were stratified based on the recent and recovering status of vegetation recruitment along with gap age, and an intact forest plot was sampled as a control treatment. The result shows that canopy opening has a significant effect on water temperature, and it has a profound influence on structuring vegetation and the crab communities in mangroves. Seedling and sapling density was 2-fold higher in canopy gaps than intact forest, and higher sapling survival was witnessed in canopy gaps. 28 species of crabs were recorded collectively from all treatments. Crabs of the family Ocypodidae were found in large proportion in canopy gaps, as the organic matter from microalgae and bacteria is their primary food base. Overall, canopy gaps in contiguous mangrove habitats are a hot spot for crab diversity and serve as a regeneration niche for seedlings and saplings by creating structural heterogeneity in the landscape. It suggests that small-scale natural disturbances, such as canopy gaps, promote habitat complexity and crab diversity.Item Foraging Guild Structure and Niche Characteristics of Waterbirds in Pong Wetland, Himachal Pradesh(Wildlife Institute of India, Dehradun, 2025) Abhishek; Talukdar, Gautam; Gopi, G.V.; Kaur, AmarjeetWetlands are one of the important habitats for waterbirds, yet the mechanism of niche segregation among the waterbird communities is understudied. This study focused on the foraging guild structure and niche characteristics of waterbirds in Pong wetland during the wintering season. The study takes into account foraging habitat (water depth, secchi depth and vegetation type) and foraging technique used by the waterbird species to understand resource partition and coexistence. The study was carried out from December 2024 to March 2025 using the point count method in two different sites of the Pong wetland i.e., Meenu khad and Gaj khad each having five replicates. The total sampling effort was 56 days with 26 days in Meenu khad and 30 days in Gaj khad. The species richness analysis of both the sites revealed Meenu khad to be more species rich than Gaj khad likely due to variation in water depth in the region, resulting in different habitat conditions. The monthly abundance of waterbirds in Pong wetland was found to be at its peak in the month of January. Generalist species such as the Eurasian Coot and Tufted Duck occupied the broadest habitat and combined niche breadth than that of specialists such as the River Tern. Furthermore, in terms of extensive foraging strategy, species such as the Northern Shoveler and Intermediate Egret occupied broader niche breadth, demonstrating behavioral flexibility in resource acquisition. The clustering of waterbird communities resulted in four functional guilds that are responsible for reducing competition and allowing species coexistence. It was found that the intraguild overlap was significantly higher than the interguild overlap (F = 54.34, p < 0.001). The null models further showed the mechanism that could be responsible for structuring the communities. It resulted in higher observed niche overlap than expected, signifying that community structure of waterbirds is largely influenced by morphological variations leading to different foraging habits, variable abundance of waterbird species and presence of abundant resources at Pong Dam. This study is the first in providing deeper understanding on seasonal waterbird abundance, niche requirements and community structure at Pong Lake. This study serves as a baseline to continue future studies in the region and assess the impacts of changing land use practices as well as changing climate on species occurrence and abundance and community structure. Furthermore, the study also showed the region to be an important staging ground for many migratory species, therefore, focusing on targeted habitat management will be crucial to support the diversity of waterbird species.are one of the important habitats for waterbirds, yet the mechanism of niche segregation among the waterbird communities is understudied. This study focused on the foraging guild structure and niche characteristics of waterbirds in Pong wetland during the wintering season. The study takes into account foraging habitat (water depth, secchi depth and vegetation type) and foraging technique used by the waterbird species to understand resource partition and coexistence. The study was carried out from December 2024 to March 2025 using the point count method in two different sites of the Pong wetland i.e., Meenu khad and Gaj khad each having five replicates. The total sampling effort was 56 days with 26 days in Meenu khad and 30 days in Gaj khad. The species richness analysis of both the sites revealed Meenu khad to be more species rich than Gaj khad likely due to variation in water depth in the region, resulting in different habitat conditions. The monthly abundance of waterbirds in Pong wetland was found to be at its peak in the month of January. Generalist species such as the Eurasian Coot and Tufted Duck occupied the broadest habitat and combined niche breadth than that of specialists such as the River Tern. Furthermore, in terms of extensive foraging strategy, species such as the Northern Shoveler and Intermediate Egret occupied broader niche breadth, demonstrating behavioral flexibility in resource acquisition. The clustering of waterbird communities resulted in four functional guilds that are responsible for reducing competition and allowing species coexistence. It was found that the intraguild overlap was significantly higher than the interguild overlap (F = 54.34, p < 0.001). The null models further showed the mechanism that could be responsible for structuring the communities. It resulted in higher observed niche overlap than expected, signifying that community structure of waterbirds is largely influenced by morphological variations leading to different foraging habits, variable abundance of waterbird species and presence of abundant resources at Pong Dam. This study is the first in providing deeper understanding on seasonal waterbird abundance, niche requirements and community structure at Pong Lake. This study serves as a baseline to continue future studies in the region and assess the impacts of changing land use practices as well as changing climate on species occurrence and abundance and community structure. Furthermore, the study also showed the region to be an important staging ground for many migratory species, therefore, focusing on targeted habitat management will be crucial to support the diversity of waterbird species.Item Influence of Predation Risk on Foraging Behaviour of Indian Desert Jird (Meriones hurrianae) in the Thar Desert(Wildlife Institute of India, Dehradun, 2025) Singh, AnanyaThe aim of the study is to understand how predation risk influences the foraging behaviour of Indian Desert Jirds in terms of time allocation of certain behaviours (vigilance and foraging), daily activity pattern and giving up densities (GUD) frameworkItem Understanding Aggregations Sites of Elasmobranchs in selected islands of the Lakshadweep archipelago(Wildlife Institute of India, Dehradun, 2025) Sawant, Chinmay Prakash; Ghanekar, Chinmaya; Johnson, J.A.This Study shows the identification of the aggregation sites of the elasmobranchs, i.e., sharks, rays, and skates, belonging to the Lakshadweep archipelago, emphasising the identification of aggregation places and traditional knowledge regarding related habitats and species. The presence of elasmobranch aggregations is biologically important as it addresses essential life processes like feeding, reproduction, and nursery grounds. Semi-structured interviews were conducted with 120 respondents, including fisherfolks and scuba divers at four selected Islands of Kavaratti, Kadmat, Bitra, and Agatti on traditional ecological knowledge and information about the presence of elasmobranch species and their aggregation sites. Sixteen aggregation sites were reported, nine for rays and eight for sharks. These aggregations occurred most frequently during the post-monsoon season and the early morning hours. The major habitats ecountered with these aggregations were shallow sandy lagoon, coral and rocky reef, sand, and open ocean pelagic zone. The interviews conducted for assessing species composition included a collective 24 species of sharks and 13 species of rays, with dominant encountered species such as the Whale shark, Blacktip Reef Shark and Tawny nurse shark, for rays Spotted eagle ray, Porcupine ray and Oceanic manta ray. 14 species of sharks are aggregating: Whitetip reef shark, Blacktip shark, and Blacktip reef shark are dominant in the aggregation sites. For the ray aggregation site total of 10 species were reported as they formed aggregations from the Porcupine ray, Spotted eagle ray, Cowtail Ray, and Indian Ocean blue-spotted mask ray. Key aggregation sites are such as Cheriyapani, Valiyapani, and Suheli Par, were identified as key elasmobranch aggregation hotspots. Pole and line, hook and line the traditional fishing practices in the islands. The result of the habitat surveys confirmed these findings, showing that lagoon areas are particularly important for the aggregation of rays, whereas coral reefs in Kadmat, Kavaratti, and Bitra host potential shark populations. In Bitra, rays were observed feeding on a locally frequent prey species called "Muchroli," suggesting distinctive trophic interactions. Moreover, drone surveys validated the presence of huge aggregations of rays in pristine reef habitats, such as Cheriyapani, Valiyapani, and submerged banks offshore, including Suheli Par and Perumal Par. These locations are likely to serve as refugia, with the best possible conditions for feeding, resting, and potential nursery grounds, primarily due to minimal human disturbance. This research provides the first comprehensive understanding of the ecological knowledge of sharks and rays, including their species and key habitats. The results highlight the imperative necessity for continuous long-term monitoring, understanding their ecology of specific fisheries management and habitat, to protect these ecologically specialised and at-risk species in the Lakshadweep archipelago.Item Assessing Ghost crab distribution, abundance and habitat use along the Coromandel Coast, Tamil Nadu(Wildlife Institute of India, Dehradun, 2025) Keerthi V; Gopi, G.V.Sandy beach ecosystems around the world are facing numerous threats and tremendous pressure due to ever increasing human population. One such threat, relevant to the Indian coastline, is the large scale plantations of shelterbelts of the exotic pine, Casuarina equisetifolia, which alters beach geomorphology. The effects of such plantations on permanent shore-dwelling organisms are poorly studied. Hence Ocypode crabs, the most conspicuous macro-invertebrate on sandy beaches, has been used as a model taxon to study the effects of different kinds of inland vegetation (Casuarina plantations, Mangrove plantations, native dune vegetation) on beach geomorphology and consequently, shore dwelling ghost crabs. The present study aims to - (1) Assess the density, distribution and demography of ghost crabs across treatments (2) Understand variations in habitat use and burrow architecture across treatments (3) Understand the effects of inland vegetation on beach geomorphology 2. A total of 24 transects, temporally replicated thrice each month between January 2025 - April 2025, were walked to estimate densities of ghost crabs using burrow counts as a proxy. 87 burrows across the treatments were cast using a mixture of Plaster of Paris and water and traits such as depth, diameter, shape and branching patterns were studied. Coast characteristics like slope, compactness, beach width, moisture and temperature were recorded at each study site. 3. Mean burrow densities and across shore distribution of Ocypode ceratophthalmus differed across the treatment types, with lowest densities in beaches adjacent to Casuarina plantations. This however wasn't statistically significant. The burrow structures also differed in complexity across treatments with the major drivers for this 7 difference being the size of the crab and the type of inland vegetation. Environmental variables were not found to have significant effects on burrow architecture. 4. The results indicate that the type of inland vegetation affects the population of ghost crabs through changes in beach geomorphology. Ghost crabs were also found to modify the structure of their burrows with changes in the habitat quality and environmental conditions, which gives insights into their adaptive capacities. The study, thus raises questions on the effects of certain management interventions, like the planting of shelterbelts on habitat quality and on the ecology of the species dwelling in the said habitats.Item Assessing Habitat Use and Activity Pattern of Hoolock Gibbons (Hoolock hoolock) in the Mosaic Landscape of Garo Hills(Wildlife Institute of India, Dehradun, 2025) Passah, Betwonsaoo; Lyngdoh, Salvador; Kumara, H.N.Primates react to environmental disruption in a variety of ways. Their home range and activity pattern are often linked with anthropogenic disturbance of the landscape. This study focuses on Hoolock Gibbons (Hoolock hoolock) in Garo Hills, Meghalaya, which is a highly arboreal primate and the only ape in India. Hoolock gibbon’s habitat in the Garo hills is being degraded due to the increase in the conversion of forest land into plantations. As most of these forests where the gibbons are located are managed by the community, these forests face overexploitation, which threatens the endangered Hoolock Gibbons habitat. This study aims to establish a baseline Hoolock Gibbon Ecology in the community-managed forest and protected area in the mosaic landscape of Garo Hills, Meghalaya, by examining their habitat use and activity pattern. The main objective is to determine the Gibbon's habitat use within its home range and examine their activity patterns in different forest types. The study is conducted in Daribokgre CR (a continuous forest patch adjoining Nokrek National Park), Dura Kalakgre CR (a small strip of CR which is surrounded by abandoned jhum and active jhum), and an Areca nut plantation which is located in Rensengre close to Selbalgre CR. In each area, one group is chosen and tracked for 20 days. Geo-coordinates and behavioural data were collected, with vegetation sampling and disturbances within a 1 ha cell size grid, which was overlaid on the location points. QGIS was used to map habitat use based on the geospatial data, and the Generalised Linear Model (GLM) was used to check the influencing factors. The activity budget was calculated to understand the behaviour patterns. Across the three studied groups, the habitat types were different group in Daribokgre (Forest group) is dominated by forest patches, the group in Dura Kalkgre (Jhum group) was dominated by abandoned jhum, and the group in Rensengre (Plantation group) was dominated by plantation, and their home range size were 24 hectares, 30 hectares, and 23 hectares, respectively. GLM reveals a significant effect only for the group in the disturbed habitat on the intensity of use. Overall, habitat use patterns and activity patterns varied across the groups, reflecting in behavioural and habitat preference.Item Influence of invasive plant species on native plant-flower visitor interactions in a scrub forest of Anaikatty, Nilgiri Biosphere Reserve(Wildlife Institute of India, Dehradun, 2025) Akilan, K P; Ramesh, C.; Gautam, Ritesh Kumar; Karunakaran, P.V.Invasive alien species are one of the top five drivers of biodiversity loss globally. Invasive alien species are known to cause changes to the biotic interactions in the invaded regions. Pollination is an important limiting process in the life cycle of plants and the pollinators potentially mediate the process of invasion through novel interactions. Invasive plants can have an impact on the native plant-pollinator interactions. 2. I studied the influence of invasive plants on the native plant-flower visitor interactions in the scrub forests of Anaikatty, Nilgiri Biosphere Reserve. I determined the change in flower visitor diversity along an invasion gradient. I also compared the visitation between native and invasive plants, by looking at the difference in composition of insect interactions with native and invasive plants. I used 20 min zigzag walks in 26 plots across three months looking at insects interacting with flowers. I also estimated the density of flowers in each plot. 3. I used generalised linear mixed effects models to draw the relationship between insect richness and the proportion of invasive flowers, and between number of visits and proportion of invasive flowers. To compare the difference in composition of flower visitors between the plant species, I performed permutational multivariate analysis of variance (PERMANOVA) with bray-curtis dissimilarity index. 4.I observed 191 unique plant-flower visitor interactions of a total of 813 plant-flower visitor interactions, formed by 68 insect visitors and 28 flowering plants. Native plants, Sida cordifolia (25%), Tephrosia purpurea (20%) and Glycosmis mauritiana (13%) and invasive plants Parthenium hysteriphorus (8%) and Ageratum conyzoides (6%) formed majority of the interactions. Hymenoptera and Lepidoptera are the insect orders with the most number of interactions. 5. The richness and number of flower visitors increase with increasing flower density. The richness and number of flower visitors show a negative relationship with proportion of invasive flowers. The composition of visitors is significantly ifferent among all native flowers and between native flowers and invasive flowers.6.This is the first study in the Nilgiris Biosphere Reserve looking at plant-flower visitor interactions in wild flowers, with a focus on the influence of invasive species. Visitation of insects to a plot has a weak negative relationship with proportion of invasive species, in this context. This study sets the baseline for future studies that could look at explaining the patterns seen, looking at relationship between the functional diversity of flowers and insects.Item Heat Hardening and the Influence of Thermal Heterogeneity of Habitat on Aboveground Activity in Spiny-tailed Lizard (Saara hardwickii)(Wildlife Institute of India, Dehradun, 2025) Vassa, Chirag Nimish; Dutta, Sutirtha; Kher, VarunHuman induced climate change has challenged the persistence of many organisms at different biotic levels and alter their interaction with the environment. Ectotherms are particularly vulnerable to anthropogenic climate change due to their reliance on external environment for various life history traits. Thermoregulatory behaviour is often used by many ectotherms especially reptiles to regulate their body temperature and will be crucial in imminent future with intensification of climate change. Although behavioural thermoregulation is widely studied, but studies looking at influence of thermal heterogeneity of a habitat on aboveground activity is limited. Moreover, with escalation in global warming ectotherms might have to rely on another mechanism in addition to thermoregulatory behaviour to combat the effect. One such physiological mechanism is heat hardening a quick response to thermal tolerance that temporarily enhances thermal tolerance, allowing lizards to withstand greater temperatures for a short period. Despite its importance very limited data is available for heat hardening capacity in reptiles. This study examined the influence of thermal heterogeneity of a habitat on aboveground activity in spiny-tailed lizard (Saara hardwickii) and assessed their heat hardening capacity. Additionally, trade-off hypothesis was also tested which has been recently proposed to explain the dynamics of thermal tolerance plasticity. I found positive influence of habitat heterogeneity on aboveground activity of the lizard. However, individuals in both the conditions spent similar amount of time in different behaviours. With respect to phenotypic plasticity i.e. heat hardening, I did not find any evidence of thermal tolerance plasticity during my experimental trials but few individuals did show increased thermal tolerance implying intraspecific variation. Additionally, the results from heat hardening experiments found no support for trade-off hypothesis. My study underscores the importance of habitat heterogeneity for species like spiny-tailed lizard which thrives in extreme temperatures. Furthermore, Lack of phenotypic plasticity in thermal tolerance increases it’s risks to overheating and dependency on behavioural thermoregulation.Item Habitat Utilisation of Asian Water Monitor (Varanus salvator) in and Around Bhitarkanika National Park, Odisha(Wildlife Institute of India, Dehradun, 2025) Rayen, W. Michael Isaac V.; Pandav, Bivash; Das, AbhijitThe water monitor lizard Varanus salvator is the largest of all lizards in India, and its distribution is restricted to certain pockets of the northeast, eastern coast and Andaman and Nicobar Islands. Despite being the largest lizard, only limited studies have been done on this species, especially on the movement pattern and home range. This study focuses on the space use pattern of Varanus salvator in the mangrove habitats of Bhitarkanika National Park, Odisha. In total, five individuals were radio-tagged with VHF transmitters in the form of a backpack. All the tagged individuals were located twice in a day, and the location(coordinates), activity and other habitat variables were recorded. The data collected were analysed for their movement pattern, activity range and overlap between individuals and the human-dominated landscape was estimated using KDE. Along with the space use environmental variables (Ambient temperature, Relative humidity, vegetation species, canopy openness, etc) were analysed individually with behaviour to the relation between them using Fisher’s test. The results from this study add more information about its activity range, movement pattern and behavioural aspects in the mangrove landscape of India, which can be useful in the rescue, rehabilitation and management of the species.Item Spatial pattern of termite mounds and its association with vegetation with experimental insights on mound repair in response to ant diversity(Wildlife Institute of India, Dehradun, 2025) Vishvavikash, I.K.Termites are considered pests all around the world in Human settlements and agricultural fields. But in Nature, termites are ecosystem engineers, they play a key role in keeping the ecosystem balanced by processing plant material and returning nutrients to the environment. In the African savanna and the Tropical Rainforest of Malaysia, termites are well studied, and termite mounds are considered nutritional hotspots. In the African continent, the genus Macrotermes is well studied, and their distribution mainly depends on the colony size. The larger colony size utilizes more space for foraging around the mound and also shows great intra- and interspecific competition between the colonies. In India, very few studies have been conducted on Termites. In this study, we investigated the spatial ecology of Termite mounds (genus Odontotermes) in the Sal-dominant Forest of Western Rajaji National Park. To understand the spatial ecology of termite mounds, we assessed their spatial distribution patterns using GPS mapping, mound morphometric characteristics, the influence of surrounding vegetation, and soil chemical properties. We studied the mound repair dynamics of the termites with respect to the predatory pressure exerted by the surrounding mound organisms. We created artificial breaches in termite mounds to monitor repair rates, while pitfall traps around mounds assessed ant diversity and abundance in the surrounding area. The Size classes of the Termite Mound didn’t show any kind of territoriality around them. Vegetation around termite mounds (Odontotermes) didn’t show any type of heterogeneity around the termite mounds. Termite mounds of the small size class show a faster repair rate than the larger termite mounds. The Ant diversity does not dictate the termite mound repair rate.