Pallas's Gull

Pallas's gull, or great black-headed gull, is a large gull, 55 to 72cm long with a wingspan of 142 to 170cm, weighing 0.96 to 2.1kg. Summer adults have a black hood, grey wings and back, yellow legs and an orange-yellow bill with a red tip; non-breeding birds show a dark mask through the eye. It is predatory, eating fish, crustaceans, insects and small mammals (Wikipedia, general species account).

It breeds in colonies on marshes and islands from southern Russia to Mongolia, nests on the ground and lays two to four eggs, and young take four years to mature. It migrates south to winter in the eastern Mediterranean, Arabia and India. It is noisy at the colony but mostly silent when breeding. The source does not mention Nepal (Wikipedia, general species account).