Some Observations on the Nest Site Selection, Nesting and Other Breeding Behaviors of Greater Adjutant Stork (Leptoptilos dubios) in the Flood Plains of Kosi River in District Bhagalpur, Bihar, India

Greater adjutant stork (Leptoptilos dubios) is the largest and rarest stork belonging to the order Ciconiformes. It is one of the threatened bird species of the world and widely considered to be endangered. The present investigation was carried out to study the nest site selection, nest tree and other breeding behaviours of Greater adjutant stork on the flood plains of Kosi river in district Bhagalpur, Bihar, India in three breeding seasons from 2019 to 2021. Total 12 breeding colonies of Greater adjutant stork were recorded in 2019, 10 in 2020 and 2021 respectively. During these periods, 277 chicks were reared in 123 nests in 2019, 282 chicks in 126 nests in 2020 and 236 chicks in 105 nests in 2021 respectively. Most of the nest trees were located on the road side in and around the villages. Storks mainly selected Kadamb, Peepal, Pakar, Gamhar and Semel trees for the nest building but the Kadamb was the most preffered tree species. Nesting materials used by the GAS were mainly sticks, twigs and fresh leaves of Pigeon wood, Jalebia, Dhaincha, Jamun, Peepal, Gulmohar, Kadamb, and Semal tree. Nests were large spherical structure made of plant sticks mostly on the top of the tree and on the tip of large horizontal branches. Both the sexes alternately shared incubation and protection of the chicks after hatching. The parent birds also collected green leaves from nearby trees for cushioning the nest . The breeding season of Greater adjutant stork was recorded between September to April in Bihar. The incubation period was ranging between 37 to 39 days. Two to three chicks on one nest were common. The adult and juveniles finally vacated the nest before third week of April.