Were there pigeons before there were cities?

From Alfred’s journal

Spent the better part of the afternoon on the ledge above the bakery, watching the pigeons work the sidewalk for crumbs. They moved like they had been issued the pavement. For years I took them for a city invention, the way soot is, something the buildings made out of themselves. Then I remembered the cliffs in a book Switch dragged up the trunk last spring, the gray birds nesting on ledges nobody built, and I thought, were there pigeons before there were cities? Which would mean the buildings are only cliffs that came late, and the pigeons have simply gone on doing what they were doing. I do not know when the stone stopped being stone and started being a town.