Just to be clear: there never was any shortage of food anywhere in New York City after Sept. 11; some deliveries were delayed on the 12th and 13 as security measures went into place on bridges and tunnels, and there was a short burst of "panic buying" on the afternoon of the 11th, but just about all stores in all our neighborhoods remained opened, and their shelves stocked.
Fishing in Central Park would be a futile exercise: all the ponds are closed systems with no outside feeders and no fish; one small lake at the north end is occasionally stocked for children's sport fishing, but that is it. As to eating pigeons, while they might be popular in other parts of the country, there are many other, abundant sources of food for the homeless here - and absolutely no evidence that homeless people have resorted to catching them here. There are also no aligators in our sewers....
A squab, by the way, is genetically prretty close to a pigeon, but is a totally different bird. Although the way some restaurants prepare it, you could probably fool me.......
Anyway, to be reduced to catching pigeons by necessity would have to mean that things had deteriorated to where Manhattan was no longer a habitable part of the world. Sure that's possible, but at that point, people would be long gone - one way or another! - and the question's purely moot. And moot points are fine for debating, but in the real world, I will choose to be as best prepared as I can with real solutions for survival.
And hey, I really don't mean to be offensive, but as a native New Yorker it sometimes really bugs me to hear folks from other parts of the country posting all these unfounded "facts" about my hometown.