Pigeon (The Veil)
From Tardis Wiki, the free Doctor Who reference
According to the records kept by the Veil, on the 83rd day of the 235th year the Veil and the Twelfth Doctor spent inside the confession dial, a pigeon somehow made its way into the castle; when the Doctor asked if "there [were] birds here", a commotion up in the rafters answered him. Neither inhabitant of the dial ever saw the pigeon again, nor figured out where it had come from. (PROSE: The Veil)
