A Survey on Heronries (Nesting Colonies) of Eight Waterbird Species at the Bank of Ujani Reservoir, Maharashtra, India

A heronry is a place where aquatic birds (mostly herons) nest together. The nesting behaviour in birds extremely ranges from widely spaced solitary nesting birds to densely packed colonies of hundreds of individuals. The nesting colonies of these aquatic birds represent spatial and temporal distribution of nests is popularly referred to as Heronries. The characteristics of good nesting sites include protection from predators, favourable climatic conditions and offers adequate stability. Colonial water birds choose the nesting sites after careful observation and evaluation of the safety condition. The present survey was conducted for three years, from September 2020 to August 2023 at fifteen sampling sites distributed among Ujani reservoir. The waterbird species selected for study are Phalacrocorax niger (Little Cormorant), Platalea leucorodia (Eurasian Spoonbill), Mycteria leucocephala (Painted Stork), Ardea cinerea (Grey Heron), Ciconia episcopus (White-naked Stork), Pseudibis papillosa (Black Ibis), Ardea purpurea (Purple Heron) and Plegadis falcinellus (Glossy Ibis). Nest diversity indices include, Dominance, Simpson, Shannon, Evenness, Brillouin, Margalef and two similarity indices viz. Bray Curtis and Jaccard were computed. The maximum count of nests 2679 was recorded during 2022-23, whereas minimum nest count 2139 was recorded during 2020-21. The nesting dominance was of Ardea cinerea during entire study period from all sampling sites under study.