Hundreds of starlings have been found dead on a road on Anglesey.
North Wales Police said they were discovered on Tuesday evening on an "unclassified road" on the island.
The birds have been sent away for toxicology tests and a postmortem to determine how they died.
But the police believe they may have the reason now.
The discovery was initially made by Hannah Stevens who said she had seen the "massive flock" flying overhead before landing and appearing to eat something in the road.
Police are also looking in to whether this is the second time hundreds of birds have died all together in exactly the same place
"We don't know how its happened", one of its officers from the rural crime policing team said.
Officers from the Animal and Plant Health Agency have collected the birds for testing.
"There is approximately 225 dead starlings and many others on the hedge either side.
"We'll need to seize some of them with the view to have them examined to look for poison or anything that might have killed them.
"If you have any information or saw anything because it is very strange then please let us know".