Conservationists are joining forces to give evidence at the inquiry into plans by Donald Trump to build a golf resort.
The organisations said the site needed protecting for wildlife
RSPB Scotland and the Scottish Wildlife Trust (SWT) are uniting to give evidence at the procedural pre-inquiry on Wednesday.
Both groups want to find an alternative solution to the developer's proposal to build on a Site of Special Scientific Interest (SSSI).
They said they want a compromise over plans for the £1bn development.
Anne McCall, head of planning for RSPB Scotland, said: "We've said all along that we're not against Donald Trump's golf course or the rest of his development, just the fact that the plans include building the back nine on a SSSI.
"Unfortunately, the developer refused to negotiate over the plans, and we now face a public inquiry which is certainly a drain on charitable resources.
"However, we will use this opportunity to try and reach an outcome that doesn't involve destroying a nationally protected area and we are pleased that we can do this together with the Scottish Wildlife Trust who share the same concerns."
Paul Gallagher, national planning co-ordinator for SWT, said: "The Scottish Wildlife Trust welcomes the additional scrutiny created by a public inquiry.
"Trump's uncompromising approach is clearly demonstrated by the lack of consideration given to other suggestions that would move the development away from the more environmentally sensitive areas.
"Both the Scottish Wildlife Trust and RSPB Scotland believe that the Scottish Government cannot sanction the effective destruction of an area just because 'the scale of the dunes, proximity to the sea and the vistas which are on offer' suit the developer.
"If Trump really wants this development to go ahead he must consider a compromise that lessens the environmental impact.
A public inquiry into the planned development in Aberdeenshire will take place later this year.