It is the first time that a large number of rare birds listed in Viet Nam Red Book have flocked to the reserve.
Experts said that the low water level of Tri An lake with many puddles full of fishes and crawdads casue birds to migrate.
The painted stork (Mycteria leucocephala) is a large wader in the stork family. It is found in the wetlands of the plains of tropical Asia south of the Himalayas in the Indian Subcontinent and extending into Southeast Asia.
It is the first time that a large number of rare birds have flocked to the reserve.