Fifteen whooper swans are killed after flying into overhead electricity cables
Fifteen migrating whooper swans may have been electrocuted on power lines close to the border.
A spokesperson for the RSPB said that the size of the birds may have prevented evasive action.
She said: "Because they are so weighty, they can't change direction too quickly."
The swans crashed into overhead cables at Carrigans, close to the border between Donegal and Londonderry. The north west is believed to be one of the most important wintering areas in the British Isles for the birds that have migrated from Iceland.
The Electricity Supply Board had installed "more effective" deflector discs to power lines, but some had been knocked from the lines during the collisions. As many as 700 whooper swans were witnessed feeding in an adjacent field.
BirdWatch Ireland said that they had collided in flight. Whooper swans have special protection under Irish law and are subject to special conservation measures.