M Sc Dissertation(WII)

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    Dietary habits and competitive interactions of scavenging raptors in the Thar desert
    (Wildlife Institute of India, Dehradun, 2025) Shukla, Manas; Kher, Varun; Kolipakam, Vishnupriya
    Scavenging raptors, especially vultures, play a crucial role in recycling nutrients and curbing pathogen prevalence in an ecosystem. Their populations in the Indian subcontinent have declined substantially in the past few decades, primarily due to the presence of toxic non-steroidal anti-inflammatory drugs (NSAIDs) in livestock carcasses. This problem worsens for vultures in the Thar desert landscapes, where large numbers of migratory vultures visit in the winter months and increase competition for resident vultures, reducing their access to resources in their critical breeding months. Therefore, understanding their dietary dependence on livestock and their interactions with other scavengers is essential for implementing targeted conservation measures. This study examines the dietary and competitive ecology of White-rumped vulture (Gyps bengalensis), other sympatric vultures, and mammalian scavengers in the Thar Desert, with additional focus on assessing risk from NSAID poisoned livestock carcasses and identifying ecological pressures from carcass use dynamics. For dietary analysis, fecal samples of White-rumped vulture (n = 10) and other migratory vultures (n = 22) of the same foraging guild collected from their identified nesting and roosting sites respectively, and were analysed using DNA metabarcoding to assess dietary composition and overlap. Questionnaires (n = 128) with pastoralists and pharmacy surveys (n = 4) were used to evaluate NSAID usage patterns, along with a geographic hotspot analysis of toxic NSAIDs. Camera traps (n = 34) were opportunistically placed at carcasses to record scavenger presence, feeding time, and aggressive interspecific interactions. Interference and exploitative competition was quantified by developing dominance and efficiency indices, and constructing hierarchies of aggressive dominance and foraging efficiency, followed by the analysis of their ecological predictors using generalised linear models.
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    Ecological Aspects of Vertebrate Scavenging in Central Indian Forests
    (Wildlife Institute of India, Dehradun, 2019) Iyer, Bhavya; Jhala, Y.V.; Qureshi, Qamar
    Scavengers assist in the cycling of nutrients in the ecosystem. However, few studies have examined the relative importance of microbes, invertebrate and vertebrate scavengers on the decomposition of carrion. Biotic and abiotic factors have both been known to affect scavenger communities. Environmental factors such as region, climate, season, habitat type, along with resource-specific factors such as carcass size influence the species which feed on a carcass as well as the time to detection of the carcass and carcass persistence time. Size in particular plays an important role in the species feeding on a carcass, with larger vertebrate scavengers more prevalent at larger carcasses. Vultures are the only vertebrates which are obligate scavengers, relying on carrion alone as a food source. Other than vultures, all vertebrate scavengers are facultative scavengers. This includes most mammalian carnivores, which hunt for prey but also make use of carcass availability. This increases the interaction routes linking the processes of scavenging and predation, increasing stability of the food web. Vultures in particular, as the only obligate vertebrate scavengers, seem to play a special role in scavenger communities. Exclusion of vultures from carcasses has been linked with longer decomposition time, more intra-species contacts at carcasses (potentially leading to increased disease spread), and increased number of species feeding at the carcass. I carried out this study to better understand the interactions between scavengers and carrion, and to observe, if any, the effect vultures and carcass size have on scavenger communities. The study was carried out in two protected areas in Madhya Pradesh – Kanha Tiger Reserve and Panna Tiger Reserve – from December 2018 to April 2019. Carcasses of animals – cattle, chital, and sambar – killed by wild predators, as well as fresh carcasses (goats and chickens) were monitored using infrared camera traps. I also carried out an experiment to observe the comparative rate at which vertebrate, invertebrates and microbes consume carrion biomass using chicken carcasses and different treatments. Vertebrate scavengers were found to remove carrion at the highest rate, at 99% biomass per day, followed by invertebrates (4.9% per day), and microbes (2.9% biomass removed per day). Despite greater vulture presence in Panna Tiger Reserve, and a relatively low vulture population in Kanha, Analysis of Similarity could not find a significant difference in the vertebrate scavenger species assemblage (the number of species and the relative abundances of those species) that visited monitored carcasses between the two study sites. Carcass size also did not significantly affect which species visiting the carcasses. I carried out occupancy modelling to estimate the probability of detecting a carcass by individual species of the carcass. Covariates which were found to affect detection probability were canopy cover, initial age of carcass, initial weight of carcass, horizontal cover, and vulture presence at the carcass. The use of occupancy modelling for estimating detection probability of carrion for different vertebrate scavengers is a unique approach, and with more data can be highly informative of the patterns and processes that govern the relationship between species and carrion. Detection corrected, model inferred occupancy gave significant improvement over the naïve occupancy estimate for all species, suggesting that carcass detection by scavengers or low abundance of scavengers was a limiting factor for visits of carcasses by vertebrate scavengers.
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    A Study of Resource Seletion by Black Kites (Milvus migrans) in the Urban Landscape of National Capital Region India
    (Wildlife Institute of India, Dehradun, 2013) Kumar, Nishant; Mohan, D.; Jhala, Y.V.
    Black Kites are the scavenger and predator raptors of the old world. In India they are synanthropic and perform the ecological role of city scavengers. Abundance and distribution of these birds suffers change due to rapid infrastructural changes in the developing cities which likely limit or change spatial layout of the available habitat and food. Many cities in the old world (London, Cape Verde, Istanbul) have experienced decline in the population of Milvus kites owing to rapid urbanization. Indian sub-continent almost lost its main scavenger, white backed vultures, in the last century. After this loss; existence of black kites, the most abundant raptor of the old world proves very vital. On these lines I carried carry out this dissertation from December 2012 to April 2013. This study focused on a) estimating the abundance of Black Kites on the Ghazipur dump site and the abundance of nesting pairs in National Capital Region (NCR), b) evaluating factors influencing nesting habitat selection combined with a broad understanding of its foraging habits and c) estimating nest survivorship in the urban landscape. I studied these parameters at selective study sites in NCR by intensive counts of birds at Ghazipur and breeding pairs at nest sites across eight study sites. Nests were searched intensively at each site while I tried to develop and test a new method to count the kites on the Ghazipur dump. Data from 116 nests and nest sites covariates were used to model nest survivorship under Known Fate scheme in Programme MARK. For my first objective, I estimated the current abundance of nesting pairs of Black Kites at 7 study sites. It ranged from 4 pairs / km2 in Sagarpur to 67 pairs / km2 in North Campus area. Nesting kites were selective while choosing a nest site, as evident by significant partial correlation between nest density, food index and green cover. The sites at the best trade-off between green cover and food availability had the highest nest densities. While developing a new methodology, I estimated around 2400 kites on the Ghazipur dump. Through behavioural observations and broad examination of regurgitated pellets, I could confirm scavenging as well as predacious nature of Black Kites. The overall probability of a nest to produce a viable fledgling was 0.45. The nest survivorship was stage specific and varied with pre-laying, incubation or nestling stage. The lower survival probability (0.60) at pre-laying stage is likely because of surplus nest formation at sites with good foraging opportunities. Understanding the importance of kites in urban ecology, studies using individually marked birds will reveal vital details of their behavioural and physiological adaptations. If future long term studies are conclusive enough, may establish Black Kites as an umbrella species of urban ecology.