Seasonal and Spatial Variation of Flock Size of Asian Openbill Stork Anastomus Oscitans at Foraging Site in Nagapattinam District, Tamilnadu, India

Seasonal and spatial variations of flock size of Asian Openbill Stork Anastomus oscitans in Nagapattinam district, Tamilnadu, India were studied during period from October 2016 to September 2017. During these study periods 48 different sites 122 foraging sites were observed. The flock size range from 1 to 19 birds and mean flock size 5.25±3.21. Flock size and availability of prey was maximum observed during pre-monsoon and monsoon season. Most commonly sighted in agriculture and marshes habitats 57% and least sighted were observed in river bank and ponds 24%. Flock size and availability of prey variation were found different season and between the habitat. Relationship between the prey availability and flock size was positively correlated. Present study reveals that variation of flock size in related to availability of prey.