I know there's rats round about our house (and I know the old adage "you're never further away from a rat than about 5 yards" or something like that). However ...
I've just seen a rat noshing away like a good 'un at the foot of our bird table. I surmise it's maybe a nursing mother, to explain its appearance at mid-day.
So rats: how tolerant should I be? Kill a couple, or aim at genocide?
We had them at the back of the garden a few years ago,in winter, and with the aid of traps and poison I killed half a dozen, and we never saw them again.
I've put down a trap just now to see if I can kill one or two more.
I'm aware that [in these parts] if they were squirrels we'd be delighted to see them (for a week or two anyway).