Two walkers first came across one of the spring traps when they found a common gull floundering on the ground.
The pair had been walking Geallaig Hill near Ballater, Aberdeenshire, on June 27 when they saw the legs of the bird caught in two traps.
They contacted RSPB Scotland and an animal officer released the bird but found it had two badly broken legs, meaning the gull had to be put down.
The RSPB searched the area with police wildlife crime officers and found evidence of eight similar - recently removed - traps attached to stakes and baited with dead rabbits, in a 200m line across the moor.
The conservation charity said the Cairngorms “should be a showcase for the best of Scotland’s wildlife”.
Police have spoken to the land managers but it is not known who set the traps.
Ian Thomson, RSPB Scotland’s head of investigations, said: “The deployment of these illegal traps has resulted in the killing of protected birds, with other specially protected species such as golden eagles, red kites or hen harriers also potentially at serious risk from this indiscriminate activity.
“The fact that this occurred within the Cairngorms National Park, an area that should be a showcase for the best of Scotland’s wildlife, makes this all the more appalling.
“It is disappointing that the perpetrator of these offences has not been identified, as is often the case with wildlife crimes.
“We hope that this appeal to the public will yield more information to bring those responsible for this appalling crime to justice.”
The Scottish Gamekeepers Association said it condemns wildlife crime.
A spokesman said: “This is the first we, as an organisation, have heard about this, so we will take time to make the appropriate inquiries.
“The SGA is an organisation which advocates best practice and condemns wildlife crime.”