Just had a quick look at the live stream seams the link keeps changing I don't know why I've changed the link. But whilst watching the female shuffling about there was a stock dove sat on a ledge just outside the nest bit risky I thought
May have been a feral pigeon but looked like a stocky to me ian
The NTU camera is pretty good...there's 3 cams, cam 1 long shot where you can see the ledge which is great when the youngsters get bigger and start running along it wing flapping. Cam 2 has a close up of the nest and at time of typing the 3 chicks, who are getting bigger by the day, are being fed and cam 3 which is one of those thermal type cameras.