I once watched a Red-tailed Hawk eating a large rat up in the girders over near Pesky Pole in Fenway... Took my attention for about half an inning.
Saw 50+ Rock Pigeons vacate the lights at Gillette Stadium in front of a Peregrine Falcon that came by us (while we were sitting in the nosebleed seats).
Saw a Mississippi Kite and Green Heron fly over Ranger stadium a couple springs ago.
Theres some impressive Monk Parakeet nests in the lights at the field in New Brittain CT.
I might start a list... Sports venue birds. Thanks for the idea!
Bill