Why are there so many feral cats in my neighborhood all of a sudden?

from my general knowledge and experience with cats, pets and feral, it is sometimes because they are running out of places to go and limited food in other places. even though you don't see rats or mice or rabbits even squirrels and chipmunks they are there underground and in trees. cats often take refuge in places that are cleaner and have less traffic so they have more of a chance at surviving.