Amur Falcon (Falco amurensis) breeds in northern China and eastern Russia (Amur) and migrates to southern Africa to spend the winter.
During this onward migration from October to December, Amur Falcons pass through Nagaland, Manipur and elsewhere in northeastern India and Bangladesh in spectacularly large numbers (100s of thousands), before moving through peninsular India and eventually crossing the Arabian Sea into Africa. A handful of birds sometimes stay on in southern India even during winter.
Return migration to its breeding grounds is faster and more diffuse with only a few birds usually seen during April and May in West Bengal, Bangladesh and northeastern India.