The royal insignia built into the tympanum above the main entrance of the palace Link , including lion and unicorn, the latter adorned with a metal chain. Also visible is some wire netting, presumably to keep birds from perching.
These are Great White Pelicans (Pelecanus crispus), as were the original London Parks birds donated by Russia. There is also however, I understand, a single American Brown Pelican (Pelecanus occidentalis) with them now.