Roost-Site Selection and Population Assessment of Gulls Wintering Along India's West Coast Reveals the Importance of Conserving Coastal Habitats

Abstract

High quality roosts play a significant role in species' population survival and such information is scarce for many gull species. In this context, identifying factors that influence roost-site selection by gulls, and the extent to which they do so, as well as suggesting appropriate management strategies to conserve coastal habitats along the Central Asian Flyway, are urgent necessities. We conducted near-shore surveys along a 121–km stretch of India's west coast between January 2015 and April 2018 to assess roost-site selection by wintering gulls. At select sites, we also conducted population assessments from established vantage points during low tide using a photograph-based total count method. We recorded five species of gulls. Generalized Linear Models showed that three habitat variables, namely the number of sandbanks, extent of sandbanks, and distance to fish-landing centres, strongly influenced roost-site selection by gulls. Ideal estuaries for gull roosting included more than two sandbanks that spanned more than eight hectares, and were within two kilometres of fish-landing centres. Zero-inflated count models revealed strong site-fidelity among gulls and showed that the sampling covariates did not influence the detection of gulls in already known sites. We recorded eight percent of the 1% biogeographic population of Brown-headed Gull, three percent of that for Pallas's Gull and two percent of that for Slender-billed Gull. Encouraging sustainable use of coastal areas for recreational activities, curbing sand mining, and including three sites (Karli, Mitbav and Mochemad) in Sindhudurg district under India's protected area network, as Community Conservation Reserves, may help conserve the wintering population of gulls along the Indian coast.