I just heard another story today about the growing rat infestation problem. I predict that within 5 years some cities will have a serious rat problem. Why? Two reasons: 1) you can no longer buy effective rat poison, 2) there are fewer cats (pets or feral). Most cities have stringent pet laws and make an all-out effort to catch strays. That's good. To a point.
Really no different than in nature where a balance must be maintained to prevent an over- population of one species.

I recently got bitched out because I have a pregnant shop cat at work. "Don't you know that cat should be spayed?". Why? "Because she's going to have unwanted kittens and that's cruel." I want kittens and already have a home for them. "Well, cats reproduce like rats and we have to control them." (Notice the real reason?)

You know, 10,000 years ago people realized that a few cats hanging around were effective in keeping the rat population down. Today, I don't need some smart ass bitch telling me otherwise.

And let's not leave Rusty out of the picture. I had a terrior who totally enjoyed catching rats out on the farm. He didn't eat them. He just neatly piled them in a heap to show off his talents. Good Boy.