M Sc Dissertation(WII)

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    Temporal niche dynamics in avian communities: an integrated analysis of spatial, tropic, and acoustic partitioning during migration in the Himalayan foothills
    (Wildlife Institute of India, Dehradun, 2026) Raju, Ardra; Jha, Ashish
    This study examined how resident bird communities respond to the seasonal arrival of migratory birds in the Himalayan foothills. Every winter, large numbers of migratory birds from Central Asia and the higher Himalayas arrive and share habitats and resources with resident species. Despite this annual event, little is known about its effects on resident bird communities. To address this gap, the study was conducted at the Wildlife Institute of India (WII) campus, Dehradun, from December to April, covering the peak migrant season and their departure. The study investigated resident birds from three perspectives: community composition, foraging ecology, and acoustic niche use. Results showed that while index of species richness remained relatively stable across months, bird abundance index increased during peak migration and declined after migrants departed. Community changes were mainly driven by species turnover, with migrant species replacing one another over time. Foraging observations of three resident bulbul species revealed that, contrary to expectations, niche breadth increased rather than decreased during periods of high migrant presence. This pattern was likely influenced by seasonal fruit availability, particularly mulberry fruiting, rather than competition with migrants. Morphological and dietary analyses further indicated substantial overlap among the bulbul species. Acoustic analyses showed that the organisation of bird vocalisations in acoustic space remained remarkably stable despite seasonal changes in species composition. Overall, the results suggest that the resident bird community at the WII campus is able to accommodate the annual influx of migratory birds without major disruption to its ecological structure. Although species composition and abundance index vary seasonally, patterns of habitat use and acoustic niche organisation remain stable. This study provides a baseline for understanding resident–migrant interactions in the Himalayan foothills and may help assess future changes associated with climate change and declining migratory bird populations.