Police are hunting thieves who snatched three kestrel chicks from Conisbrough Castle.
The birds, a protected species, were taken from their nest last Thursday afternoon and both South Yorkshire Police and the Royal Society for the Protection of Birds have been alerted to the theft.
The chicks and their mother have become a popular attraction with visitors at the English Heritage owned castle in recent weeks since taking up a nest there.
A spokesman for English Heritage said: “The chicks have been with us for a little while and lots of people have seen them.
“It is very disappointing and sad for us that this has happened and we hope people will be able to help us with information aout what happened and their whereabouts.”
The chicks were nesting on a window ledge in a wall of the 12th century Norman castle and were taking during Thursday afternoon after a window was smashed.
The theft drew criticism from users on the Castle’s Facebook page.
Serena Deakin posted: “Disgusting! Hope they find who did it and throw the book at them!” while Angela Cheesmond wrote: “Shocking! I live close by and see the parents hunting, very sad.”
Kestrels are listed by the RSPB as a protected species, aftrer numbers fell into decline in the 1970s, possibly as a result in changes in farming.
The society currently listed the birds as being on its ‘amber list” which aims to protect birds in decline.
n Anyone with information can contact police on 101 or Conisbrough Castle on 01709 863329