It depends whether they do it as a rolling change - just changing logos as notices/shirts/vehicles need replacing dramatically keeps costs down.Every time someone like the RSPB changes their main logo it must cost more than it is worth. They will presumably repaint their vehicles, produce new staff shirts and jackets etc, update notice boards and entry signs, and so on.
I seem to remember that a previous rebranding cost well into seven figures. It would be good to know how much this one has cost and what the benefits are expected to be.
The general idea is certainly good.
Overall though, I think they have missed a trick. Instead of going for a bird that they have had success with, they could have used the symbol to draw attention to something like the plight of the Hen Harrier.