Riccardo Volpi, 27, and Daniel Volpi, 25, were found guilty of offences under the Wildlife and Countryside Act 1981 at Kirkwall Sheriff Court today.
The brothers, from St Andrews, act as guides for Italians who go to Orkney on shooting holidays, prosecutors said.
Members of the public called police after spotting the pair with a group of Italian tourists shooting and killing snipe and grouse on Birsay Moors RSPB reserve on November 7 2012.
Craig Harris, procurator fiscal for wildlife and the environment, said: “These individuals deliberately took a group of tourists on to the RSPB reserve. There was clear signage in the area and they should have been well aware of its status and that they didn’t have permission to shoot there.
“We take people breaking our wildlife laws very seriously. This conviction highlights that message.”