I wonder why the population increases. Do they belong there from origin?

I heard our new plague (in the cities) will be rats. They increase fast and the reason is the left overs from fast food restaurants + trash (saw them at the trash cans at parking lots at night as well).

Next to that the pigeons are a burden. Last year a hunter killed them, this year? I should have emptied the nest. They breed the entire year. It gets messy, poop everywhere not to mention the noise and the fruits they eat. ☹️