On the odd occasion they’d get mice in the house, my parents living in Melbourne had difficulty would have difficulty getting rid of them.

Five years ago I moved out into a tiny rural town, and saw and heard mice very regularly (the house’s previous owner had only been around every couple of weeks). But I haven’t had the slightest difficulty in slaying them: I put a couple of traps in areas I’d seen mice traversing, and was catching them within hours, occasionally as much as a day or two, from hearing or seeing evidence of the mouse. (And if I saw one, I’d give it a verbal warning to flee for its life. Don’t know if any heeded it.) Within a few days I stopped even bothering with bait. In that first year, I lost count somewhere around fifty. Each year the number has dropped. This year, I’ve had only one since last autumn (it’s now mid-summer), slain before I even saw or heard it.

Anyway, we decided (lightheartedly) that it must be the difference between town mouse and country mouse.¹

¹ See Aesop’s fables, if you’re not familiar with the expression.

Darwin agrees. I've watched live how this goes with a young family of rats. The first 2 got caught in the trap and the others were already pretty scared off by the closing mechanism kicking in. Left it like that for a couple of minutes, then I put the caught ones somewhere else then reinstalled the trap. The next 3 nor the mother came anywhere near the trap. Not even after moving it to a different location, nor with different types of food inside, nor with a different trap with a somewhat different shape.