The organisation originally objected to plans to build an 11-turbine wind farm near the outspoken businessman's luxury golf resort in the north east of Scotland.
But it is one of a number of bodies that have now dropped their opposition to the development.
The change of stance prompted Mr Trump to say: "Their name should be changed to RSKB, Royal Society for the Killing of Birds, to reflect their pro-wind turbine position. They should close their doors and not waste taxpayers' money."
Last month the Aberdeen Renewable Energy Group said that RSPB Scotland, the Civil Aviation Authority, National Air Traffic Services and the Ministry of Defence had all lifted their objections to the £230 million 11-turbine European Offshore Wind Development Centre (EOWDC).
The billionaire is opposed to the offshore wind farm, claiming it will ruin the view for golfers at his course which opened to the public in July.
He has put plans for a hotel and houses on the Menie Estate course on hold until a decision is made on the proposed wind farm off the coast of the links.
Mr Trump said the RSPB had opposed his plans for the site, stating: "This group of self-serving and ill-informed individuals fought us harder than any other group.
"The golf course I have built is already considered, perhaps, the best in the world. The hotel I am planning would likewise be far superior to any hotel in Scotland, England, Ireland and, hopefully, anywhere in Europe.
"However, if the 80-storey, Aberdeen-destroying wind turbines are going to be built in Aberdeen Bay, I will not invest one additional pound in this magnificent development."
EOWDC project spokesman Iain Todd said last month that the removal of a number of objections is "another significant step forward for the scheme".
EOWDC partners hope to get "a green light on its consent application from the Scottish Government later this year", he said.
An RSPB spokesman said: "Any individual is entitled to their opinion on the work of RSPB.
"Trump International is a very successful business organisation dedicated to maximising its financial returns. The RSPB is a nature conservation organisation dedicated to saving our threatened wildlife and working towards creating a world richer in nature.
"We assess each planning application on its own merits. Regarding RSPB Scotland's position on the Aberdeen Bay windfarm, we have been engaged in this project for at least nine years. During this time we set out our concerns fully and asked the developer to examine them in detail. This resulted in a considerable reduction in the number of turbines and a change in the layout.
"This, coupled with our own research and that conducted by the developer, assures us that the threat to sea birds in the important waters of Aberdeen Bay is now small.
"Together with other conditions agreed about future monitoring and research, this allowed us to withdraw our objection. We wish other developers were as willing to adapt schemes to meet the serious concerns of evidence-based objectors."