"We estimate that during the peak migration 12,000 to 14,000 birds are being hunted for consumption and commercial sale every day," said a report by Conservation India.
"We further estimate that a mind-boggling 120,000 to 140,000 birds are being slaughtered in Nagaland every year during their passage through the state," it said.
Investigators from the Bangalore-based wildlife conservation NGO visited Doyang reservoir in Wokha district of Nagaland last month to document the shocking massacre of tens of thousands of the raptor.
"This is probably the single largest congregation of Amur falcons recorded anywhere in the world and it is tragic that they meet such a fate," the report said.
The report said hunters lay permanent nets close to the water reservoir to trap the birds when they come to roost during late evenings or when they leave early in the morning.
Besides killing them for meat, it said the captured birds are kept alive in mosquito nets or cane baskets so that they can be sold alive in markets.
Demanding enforcement of the ban on killing of these winged guests, Bombay Natural History Society director Dr Asad Rahmani has written to Union Environment Minister Jayanthi Natarajan.
He has suggested that both the Centre and Nagaland government take immediate steps to protect this species and also create awareness among local communities.
The Amur falcons arrive in huge numbers in October in northeast India from Siberia en route to their final destination
