I'll go with Limbaugh's take on the issue. The birds did a wonderful job of killing off the pidgeons.
People don't realize this, but there are PLENTY of hawks in Manhattan. Central Park is larger than Monaco.
Tell ya what, if they want a new home for them Hawks they can move em to my building. We got so many damned pigeons around here it looks like a casting call for a Hitchcock movie.
And rats, rats with wings, squirrels, ...
What's the problem?
Next thing you know, they'll let some practitioner of voodoo in the building, and the hawks will
have to go in order to protect the chickens used for blood sacrifices.
That they do. We had a Peregrine that would roost on the building I used to work in. The problem is that hawks & falcons are territorial, and will drive off other competitors in the area, so the effectiveness as a "flying rat" killer is somewhat diminished.