Police have said they don't know who or what has killed around 300 starlings on Anglesey.
North Wales Police posted a video of the dead birds strewn across a country lane on the island.
Officers have taken some of the birds to be tested for the cause of death.
A spokesman said: "At this stage we are keeping an open mind as to the cause of death."
An officer from the force's rural crime team said the birds had been found on the road and in the hedges that line it, but strangely no dead bodies had been discovered in the fields on either side of the road.
He said: "It is very strange. We have got officers from the animal health agency who have seized some of the bodies to be tested, looking for poison, or looking for any other thing that might have killed these birds."
Detectives said the grim discovery was made on Tuesday evening about 3.45pm.
Anyone with information is asked to contact North Wales Police on 101.
