A murmuration of the endangered species was reportedly spotted in the sky on Tuesday near the village of Bodedern by Hannah Stevens.
But when she returned an hour later she found around 300 of the birds lying dead in the road and in the bushes lining the thoroughfare, her partner told Sky News. Bizarrely, none were found in the surrounding fields.
“At this present time, it is an absolute, complete mystery to us,” said North Wales Police’s rural crime team manager Rob Taylor. “We’re trying to get to the bottom of it, however we’re still scratching our heads.”
Experts from the government’s Animal and Plant Health Agency were called in to examine the birds, searching for traces of poison or any other cause of death.
Mr Taylor issued an update at 4pm, saying his team had been told ”different stories” in interviews about the incident, but asserted he would be “very surprised” if it was poison that had caused the hundreds of birds to drop dead, given there were no carcasses in the nearby fields.
At 7pm, the rural crime team wrote on Twitter that they believed they may have solved the mystery, but were awaiting the toxicology and post mortem results before confirming to the public.
Similar incidents in which hundreds of dead starlings are mysteriously found have previously been reported in The Hague, Utah, Rome and the UK.
The birds are a red list species – the most severe category on the RSPB’s endangered list.
Additional reporting by PA