THIS is the rock dove, the pigeon that one sees in abundance at San Marco square in Venice! As I said before, I don't understand why in your text they describe this as a feral bird, comparing it to the wild dove. It seems to me that the columba livia is very tame and I have the photos to prove it!
I think we can reconcile all these facts if we agree that feral, at least here, means that it was a breed once kept as pets, or almost as pets, living close to man anyway, and which has now spread to the natural environment.
I'm not sure if this is actually the correct technical understanding of the term in this context, but it does correspond to the idea of "feral children", which I am familiar with, which is where a baby or youngster grows up in the wild, sometimes suckled or raised by wild animals, and never has contact with humans in infancy (eg Kaspar Hausen, Mowgli etc...).