Tran Duc Duy, a local resident, said he discovered the bird while surveying a flock of Asian openbills at the wetland on Sunday.
The bird's leg had been trapped for about a week, leaving its foot badly injured and nearly severed, Duy said. He carefully removed the trap before releasing the bird.
Hundreds of Asian openbills (Anastomus oscitans) have recently been recorded at Con Chim, where they forage in surrounding fields during the day and return to roost in the evening.
The species is classified as Least Concern (LC) on the International Union for Conservation of Nature (IUCN) Red List, but local authorities said it plays an important role in wetland ecosystems.
Following the birds' arrival at Con Chim, authorities have stepped up awareness campaigns, increased patrols and warned against illegal hunting, trapping and trading of wild birds in accordance with a 2022 government directive.
