The three chicks had not even started to fly

The protected birds were killed with a shotgun despite their nest being perched 70ft high on a rock face in a working quarry.

Workers at the limestone quarry near Leyburn, North Yorkshire, had been keeping a watch on the progress of the six-week-old birds of prey and were even running a book on when they would start to fly.

But staff noticed the distressed mother and found the dead birds when they inspected the nest using a hydraulic platform.

This mindless killing is appalling David Hirst, RSPB

The quarrying company RMC Aggregates has now offered a reward for information leading to the conviction of the gunman.

Stuart Keighley, director and general manager, said: "Our staff are devastated and out to catch the culprits.

"Last year three chicks were raised in the quarry and the staff were keeping an eye on the nest this time around.

"Leyburn is a small place where everyone knows everyone else's business so we hope this reward will encourage someone to lead us to those responsible."

Hefty fine

David Hirst of the RSPB said: "These are very rare and special birds and there are probably only a dozen pairs in the Dales.

"This mindless killing is appalling and I feel very sad for the people at the quarry who have done their best to protect them.

"This comes on top of other reports where peregrines have been targeted and so far it does not look like it will be a good season for the falcons."

North Yorkshire Police are investigating the killing.

The falcon, which can fly at speeds up to 112mph, is protected under the Wildllife and Countryside Act.

Anyone found guilty of harming the bird faces up to six months in prison and a fine of up to �5,000.