Travelling around Europe I've noticed that different towns seem to have different bird fauna. Fair enough, you wouldn't expect the same things in Scandinavia as the Mediterranean but there seem to be differences on a closer level. I've not studied this at all but recall numbers of crows in Berlin. Most European towns still have lots of house sparrows, unlike London, and few seemt to have feral pigeons (perhaps exterminated or given contraceptives?).
Reminded of this by the following picture - collared doves seem to be very common in Athens. Did they arrive from that part of the world?
http://www.wildabouttheworld.com/gal...to/325/cat/502