Two rare young hen harriers which had been satellite-tagged have vanished from Lancashire in unexplained circumstances, conservationists said.
The two female birds, named Sky and Hope, fledged from nests on the United Utilities Bowland Estate earlier this year, the RSPB said.
They were among the first hen harrier chicks to fledge in England since 2012, with just four successful nests for the threatened bird of prey in the country this year.
The two birds were fitted with lightweight solar-powered satellite tags, which are designed to be operational for around three years so that scientists can track their movements, but both tags have stopped transmitting.
Sky’s signal stopped suddenly on the evening of Wednesday, September 10, when data suggested she was roosting, while Hope’s last known location was sent on the morning of Saturday, September 13.
The hen harrier has been pushed to the brink of extinction as a breeding bird in England as a result of historic persecution, and ongoing targeting of the birds because they prey on red grouse.
The plight of the birds sparked a demonstration at Bowland this summer, with dozens of people turning out to demand better protection for the birds.
The local conservation group, named Skydancer, has won this year’s National Lottery Award for Best Education Project.
The award was presented by TV presenter and hen harrier campaigner Chris Packham.
Speaking of the Bowland birds’ disappearance, he said: “It’s incredibly disheartening to discover that two of this year’s chicks have already apparently failed to survive. It shows how vulnerable hen harriers are.”
The RSPB is offering a £1,000 reward for information about the birds. Anyone with information should call the RSPB’s confidential hotline on 0845 466 3636 or ring Crimestoppers on 0800 555 111.