The UK's largest colony of Arctic terns has abandoned small islands off Wales' coast after a peregrine falcon decided to nest there.
The birds left The Skerries, a group of rocky islets off Anglesey, earlier this year. There were 2,814 breeding pairs recorded in 2019.
Normally a peregrine falcon would not have nested there.
But it chose to because the RSPB wardens were not there due to the coronavirus pandemic.
The RSPB said some of these birds have now been discovered at other tern colonies across Wales, England and Ireland.
RSPB Cymru's north Wales wetlands warden, Ian Sims, said: "It was devastating to see the desertion of The Skerries this year, so it's really heartening to know that a large proportion of the terns have been able to use the network of well-managed colonies around the Irish Sea to give themselves a second chance of raising young this season."
During the summer, RSPB Cymru wardens normally live in a lighthouse on The Skerries, but because of Covid-19 they were not there.
With no people around, an immature peregrine took up residence, causing the terns to leave.
British Trust for Ornithology licensed ringers had marked a percentage of the nesting terns, enabling members of the public to report their locations.
Nearby Cemlyn Lagoon Nature Reserve, managed by North Wales Wildlife Trust, and another Welsh site, saw increases of up to 1,000 breeding pairs of terns between them.
Because of of the ringing, it is known these birds came from The Skerries.