WII Digital Repository
Established in 1982, Wildlife Institute of India (WII) is an internationally acclaimed Institution, which offers training program, academic courses and advisory in wildlife research and management. The Institute is actively engaged in research across the breadth of the country on biodiversity related issues.
The Institute's idyllic campus that has been carefully developed to create state of the art infrastructure encourages scholarly work.
This Repository is the digital asset management system which integrates the intellectual output in the form of research articles, Theses and other scanned documents. This Repository facilitates the share and exchange of intellectual output of the institute.
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Breeding biology and diet of Tawny eagles (Aquila rapax) in desert National Park, Rajasthan, India
(Wildlife Institute of India, Dehradun, 2026) Varma, Gayathri; Kher, Varun S.
The Tawny Eagle (Aquila rapax), is raptor species, found across the Indian subcontinent, widely spread and poorly studied. There is very limited quantitative information present on the nest-site selection, breeding behaviour and diet selection of Tawny Eagles. This study investigates the factors influencing habitat selection, breeding ecology and diet composition of the population of Tawny Eagles in the Thar desert landscape of Rajasthan, India, during the 2025-2026 breeding season. This study aimed to provide a baseline understanding of the species ecology by examining nest-site selection, spatial distribution of nests, parental behaviours, provisioning behaviours and seasonal changes in prey compositions. Nest search was conducted across approximately, 2000 km2, with approximately 4000 km of nest search effort with active nest tree characteristics mapped, and distance between the nest and the protected grasslands calculated. A total of ten nests were found across the study area, with all nest occurring within, or in close proximity to the protected grasslands in Desert National Park. Nine out of ten nests were either inside enclosures or located immediately adjacent to them, with an average distance of 1.56 km from enclosure boundaries. Nest trees were predominantly Prosopis cineraria, with nesting trees averaging over 7.5 m in height and providing large crown structures suitable for nest placement, with all nests being placed at the top of the tree. As all the nests were recorded in only a small part of the study area, a rapid population survey was conducted across the study area to determine the spatial distribution of the species across the study area. Raptor surveys covering 734.78 km across 63 grids recorded 14 Tawny Eagle sightings, confined largely to areas where nests had been located. Breeding behaviour was studied using focal observations and CCTV monitoring across active nests, generating approximately 900 hours of behavioural data. Breeding was found to occur in the winter months, with most eggs being laid in December and January, hatching in the months of January and February, with fledging occurring by the end of March through April. Results showed differences in parental roles, with females primarily responsible for nest attendance and chick care, while males acted as the primary providers of prey. Female nest attendance decreased as chicks matured, while chick vigilance increased with age. Provisioning behaviour demonstrated seasonal variation, with Spiny-tailed Lizards (Saara hardwickii) becoming the dominant prey item during warmer months. Diet composition was assessed using pellet analysis, CCTV observations, and drone surveys, resulting in 224 prey records from nine nests. Tawny Eagles showed dietary flexibility, with mammals (41.9%) and reptiles (40.1%) comprising the majority of prey items. Diet composition changed significantly across months and nesting stages, with a shift from mammalian prey during colder months towards increased reptilian prey as temperatures rose and Spiny-tailed Lizards became more available. Overall, this study highlights the importance of protected grassland habitats within Desert National Park for supporting Tawny Eagle populations by providing suitable nesting structures, reduced disturbance, and productive foraging habitats. The findings provide the first detailed quantitative assessment of habitat selection, breeding behaviour, and diet composition of Tawny Eagles from the Indian population and establish a foundation for future long-term studies on population status, reproductive success, and conservation requirements of this species.
Population and behavioural responses of rodents and reptiles to woody encroachment in the Thar desert
(Wildlife Institute of India, Dehradun, 2026) Pawar, Himani; Dutta, Sutirtha; Kher, Varun
Woody encroachment is increasingly modifying open ecosystems worldwide, often altering trophic-level interactions and species composition. In the Indian Thar Desert, Calotropis procera is rapidly expanding across grassland and scrubland habitats, but its ecological consequences for desert fauna remain poorly understood. This study assessed the effects of varying levels of Calotropis procera encroachment on habitat structure, predation pressure, and behaviour and abundance of nocturnal rodents and two diurnal lizard species in and around Desert National Park, Jaisalmer. Field surveys were conducted across no, moderate, and high encroachment levels of C. procera during 2025–2026. Responses of nocturnal rodent community were assessed through burrow counts and giving-up density (GUD) experiment. Reptile responses were assessed through abundance surveys and flight-initiation distance (FID) experiment, and clay model experiment was designed to quantify predation pressure. Rodent abundance, measured through active burrow counts, declined from no encroachment plots to moderate and high encroachment levels. Conversely, giving-up density at artificial food patches was greater in no encroached plots - indicative of greater predation risk perception - compared to moderately and highly encroached habitats. Lunar illumination interacted with encroachment level to influence rodent foraging decisions, indicating the role of habitat structure and environmental conditions in shaping behavioural responses to predation risk. Reptile species exhibited contrasting responses to woody encroachment. Acanthodactylus cantoris showed declines in abundance with increasing encroachment. Behavioural response mirrored this pattern. Flight-initiation distance of Acanthodactylus cantoris decreased substantially with increasing encroachment. In contrast, Trapelus agilis occurred at higher densities in highly encroached areas than non-encroached areas and its FID was primarily influenced by refuge availability and starting distance rather than encroachment level.
Predation-risk experiment revealed context-dependent effects of encroachment. In scrubland habitat, predation was faster in moderate and high encroachment plots than in no encroachment. Habitat influenced predation pressure too, as clay models faced higher predation rate in grassland than scrubland. This study demonstrates that woody encroachment produces species-specific ecological consequences, and continued expansion of Calotropis procera has the potential to reshape community composition through behavioural responses and trophic interactions, in the Thar Desert. Management interventions aimed at maintaining and preserving open habitats may therefore be important for conserving faunal diversity in this important conservation ecosystem.
Ant-ics and appetites: mapping ant (Formicidae) diversity and resource selection in Agumbe
(Wildlife Institute of India, Dehradun, 2026) Biju, Ashwati; Gautam, Ritesh Kumar; Kolipakam, Vishnupriya
Ants are important components of terrestrial ecosystems, yet information on their diversity, behaviour, and resource use in non-protected landscapes of the Western Ghats remains limited. This study investigated ant diversity, community composition, behaviour, morphometrics, and resource selection across forest patches, grasslands, and areca plantations in the Agumbe landscape of the central Western Ghats. Field surveys were conducted between December 2025 and March 2026 using visual encounter surveys and active hand collection. Ant diversity, abundance, community composition, behaviour, and morphometric traits were documented. Resource selection experiments were conducted on Trichomyrmex colonies using sugar, rice, and seeds that differed in physical texture. A total of 75 ant species, 423 occurrence records, and 10,284 individuals were recorded. Forest patches supported the highest species richness, abundance, and diversity, while plantations and grasslands supported fewer species. Community composition differed significantly among habitat types, with habitat characteristics influencing ant assemblages more strongly than stream position. Behavioural observations documented a range of ecological roles, including predation, scavenging, honeydew collection, seed collection, brood transport, recruitment, and nest maintenance. The study also recorded ten putatively undescribed species, new state records, and worker polymorphism in Lepisiota wroughtonii. Resource selection experiments showed a clear preference hierarchy of Sugar > Rice > Seeds, indicating that resource characteristics might influence foraging decisions. The findings highlight the ecological and taxonomic importance of the Agumbe landscape and provide baseline information on ant diversity, behaviour, and resource use in the central Western Ghats. The study also emphasizes the importance of forest patches for conserving ant biodiversity in human-modified landscapes.
Influnece of prey availability and abiotic factors on habitat utilization of mugger crocodile (Crocodylus palustris) and interactions with Fishermen in the Moyar-Bhavanisagar landscape
(Wildlife Institute of India, Dehradun, 2026) Thompson, Bryan Rana; Gopi, G.V.; Das, Abhijit
Crocodilians are considered to be apex predators of freshwater ecosystems, yet little is known crocodilians often compete with fishermen over fish resources. This study aims to measure the influence of prey availability (fish biomass) and abiotic features on the habitat utilization of mugger crocodiles in the Moyar river and to quantify crocodile-caused net damages and the associated costs experienced by fishermen in the Bhavanisagar reservoir. Model selection revealed that fish biomass was the best fit model for crocodile habitat utilization, along with sandy banks (which was most preferred for basking) and wider river sections, which showed weaker model fit for habitat utilization. Questionnaire surveys involving fishermen and experimental net monitoring in the reservoir revealed that the perceived frequency of crocodile caused net damage is approximately 2.2 times higher than the observed frequency of net damage. The mean estimate of losses experienced by fishermen over a four month period in the reservoir due to crocodiles was calculated to be approximately Rs. 32,029. Nets placed closer to the bank experienced more damage by crocodiles than nets placed further from the bank. This study highlights the importance of prey availability and scientific management and monitoring of habitat for crocodile populations and provides baseline information on fishermen-crocodile conflict and can aid in informing stakeholders in implementing mitigation measures and compensation schemes.
Altered habitat alter habits; Behaviour and space use of Asian elephants in the Valparai Plateau
(Wildlife Institute of India, Dehradun, 2026) Komarla, Joshika; Nigam, Parag; Kumar, Ananda; Nath, Anukul
As habitat loss and fragmentation continue to increase, mega-herbivores such as Asian elephants (Elephas maximus) increasingly traverse mixed-use landscapes where human-elephant encounters are frequent. Such encounters may influence elephant behaviour by altering activity patterns over time, modifying the relative frequencies of behavioural events, and shaping the behavioural repertoire exhibited. In this context, I examined the effect of human presence and associated activities on elephant behaviour on the Valparai Plateau, a rainforest-plantation mosaic in the Anamalai Hills of the Southern Western Ghats. Behavioural observations were conducted over a 104-day field season using 370 instantaneous group scans and 499 focal observations of identified individuals. My findings suggest that human presence did not have a measurable impact on the behavioural composition of time activity patterns; however, encounter characteristics – particularly crowd size and human identity – did account for variations in these patterns. Increasing crowd size was associated with a 10 % reduction in predicted time allocated to foraging. Behavioural events such as vigilance, avoidance, and agitation were more sensitive to anthropogenic influence, with effects evident in both coarse- and fine-scale analyses. The odds of stress-induced behaviours were sevenfold in the presence of humans; however, beyond a threshold distance of approximately 70 meters (69.9 meters), the likelihood of such responses declined substantially. Proximity to elephants and human identity were important predictors for this response. Additionally, different human groups elicited different stress-induced responses, with Forest Department personnel eliciting more avoidance and agitation responses than expected; however, this pattern requires further quantitative assessment. Herd cohesion was not affected by human presence and was weakly affected by encounter characteristics, with biological parameters like age and sex explaining the pattern better. Habitat selection analysis using Manly’s Selection Ratio suggests that natural habitats such as forest fragments, riparian sections, as well as Eucalyptus stands were preferentially selected for, and used disproportionately to their availability, whereas dominant landscape features like tea and coffee plantations , were used less than expected relative to their availability, during daylight hours. These findings suggest that elephants inhabiting mixed-use landscapes with a long history of both human use and elephant activity may tolerate human presence at a broad level, but certain encounters may still be perceived as risky