Nesting Ecology of the Oriental Darter (Anhinga melanogaster) in a Multi-Species Colonial Waterbird Assemblage at Sur Sarovar Bird Sanctuary, Agra
DOI:
https://doi.org/10.59436/jsiane.449.2583-2093Keywords:
Oriental Darter, breeding ecology, multispecies nesting colony, riparian wetland, Prosopis juliflora, nesting site selection, species dominance.Abstract
This study examines the nesting ecology of the Oriental Darter (Anhinga melanogaster) in a multispecies colonial waterbird assemblage at Sur Sarovar Bird Sanctuary, Agra, Uttar Pradesh. The present study documents the nesting occurrence of Oriental Darter within a multi-species colonial nesting assemblage comprising 13 waterbird species, providing a comparative framework to assess its relative nesting abundance, dominance, and ecological constraints. The breeding ecology of habitat-specialist waterbirds within multispecies colonies provides important insights for wetland conservation. Surveys conducted during the breeding season in year 2025 recorded seven active breeding sites; however, Oriental Darter nesting was restricted to a single large riparian site dominated by Prosopis juliflora. This site supported 1,239 nests belonging to 13 waterbird species, indicating high species richness but uneven nesting distribution. The Eastern Cattle Egret was the numerically dominant species, contributing 56.1% of total nests, followed by Little Egret (18.7%). In contrast, the Oriental Darter accounted for only 1.5% (19 nests) of the nesting population, reflecting low numerical abundance but strong habitat specialization. Diversity analysis using Shannon–Wiener and Simpson indices revealed moderate species diversity with low evenness, supported by a high Berger–Parker dominance value (d = 0.56). All Oriental Darter nests were located in the upper canopy of Prosopis juliflora trees, emphasizing the importance of vegetation structure, canopy height, and hydrological stability in breeding site selection. The restriction of 100% of darter nesting activity to a single breeding site highlights the species’ vulnerability to localized habitat disturbance. These findings underscore the need for site-specific conservation measures focused on protecting structurally complex riparian habitats to sustain breeding populations of the Oriental Darter within multispecies colonial systems.
References
Singh, L. A. K. (2012). Ecology and conservation of wetlands in Uttar Pradesh. Indian Journal of Ecology, 39(2), 167–173.
Sharma, S. K., & Joshi, V. (2008). Avifaunal diversity of Soor Sarovar Bird Sanctuary, Agra, Uttar Pradesh. Zoos’ Print Journal, 23(12), 9–12.
Islam, M. Z., & Rahmani, A. R. (2004). Important Bird Areas in India: Priority sites for conservation. Bombay Natural History Society & BirdLife International, Mumbai.
Kumar, A., & Gupta, S. K. (2016). Status of waterbirds and conservation challenges in selected wetlands of Uttar Pradesh. Journal of Wetlands Ecology, 10(1), 12–22.
MoEFCC (2017). National Action Plan for Conservation of Migratory Birds and their Habitats along the Central Asian Flyway (2018–2023). Ministry of Environment, Forest and Climate Change, Government of India.
Roshnath, R., Sinu, P. A., & Raghavan, R. (2017). Nesting tree characteristics of heronry birds of urban ecosystems in peninsular India: implications for habitat management. Current Zoology. — tree species used, nesting heights, and management implications for urban & mangrove heronries.
Subramanya, S. (2005). Heronries of Tamil Nadu. Indian Birds — statewide inventory, distribution patterns and conservation notes for Tamil Nadu heronries
Narayanan, S. P. & Vijayan, L. (2007). Status of the colonial breeding waterbirds in Kumarakom heronry, Kerala, Southern India. Podoces — multi-year nest counts and status of Oriental Darter / other species at Kumarakom (classic Indian heronry case study).
Datta, T. & Pal, B. C. (1993). The effect of human interference on the nesting of Openbill Stork at Raiganj Wildlife Sanctuary. Biological Conservation — one of the early Indian studies on human disturbance and nesting success / spatial partitioning in heronries.
Gopi, G. V. & Pandav, B. (2011). Nest space partitioning among colonial nesting waterbirds at Bhitarkanika mangroves, India. (World Journal of Zoology / WII thesis outputs) — nest spacing, interspecific relationships in a large mangrove heronry.
Jha, K. K. (2012). Some breeding and ecological aspects of heronry birds at Soor Sarovar Bird Sanctuary, Agra, Northern India. Asian Journal of Conservation Biology — species composition, phenology and nest counts for a semi-arid heronry.
Frank, S. J. D., Gopi, G. V., et al. (2021). Heronry distribution and site-preference dynamics of tree-nesting colonial waterbirds in Tamil Nadu. PeerJ — recent mapping, drivers of site occurrence and modern survey data across many heronries.
Gohel, T., Solanki, D., et al. (2021). Studies on nesting colonies of heronry birds in Bhavnagar city, Gujarat. Indian Journal of Ecology — urban heronry census, species and seasonal timing in Gujarat.
Tiwary, N. K., et al. (2015). Two new nesting colonies of Painted Stork Mycteria leucocephala from northern India. Indian Birds — short note documenting new colonies and their breeding timing.
Downloads
Published
Issue
Section
License
Copyright (c) 2025 Maharaj Singh Educational Research Development Society
This work is licensed under a Creative Commons Attribution 4.0 International License.
