They will have a joyous time with it. And you might find eviscerated mice under your couch one day. But my two dumbass fur balls just thought they were awesome toys.
Never figured out quite when they stopped coming in. The only really humane way to kill em is snap traps. I probably went through a couple dozen of them before they stopped showing up.
I was against using poisoned food traps because the last thing I wanted was my cat consuming a poisoned mouse. But, since our whole neighborhood had a problem with the mice, I wouldn't be too surprised if a neighbor did it.
We actually discovered something that worked far better than peanut butter - Reese's peanut butter cups. You break off a little piece, squish it into a ball, and place it on the bait lever. Not a single trap misfired once we switched to that.
I feel like depends on the cat. I found mine as a list kitten that we assumed got outside and then was starving and almost dead. He's always been N indoor cat. Had never seen a mouse in the 8 years he was alive. I go out of town for a day and night and come back to a decapitated mouse in the apt. Fool took care of shit without even knowing. Then years later, we move into a house and a mouse gets in some how. My cat finds the mouse, kills it, walks around with it, then drops it in the hallway for us to clean up. If he had been taught how to catch mice when he was a kitten, I he wouldn't have been starving to death. But when a mouse showed up, he knew exactly what to do.
Mice and some other pests have evolved an instinctual aversion to the smell of cats, it triggers their fear response. Just having the cats around might have been good enough.
You are lucky, in my previous flat there were hoarders-alcoholics that lived on the next floor, one day they brought mice with whatever shit they decided to take. At first they were contained on their floor, but after a while they were everywhere. Cat played with them at first >_< and then got bored. After 10 or so that traps killed (in a month) I moved out.
Your experience reminded me of "Tom," the farm cat who lived in the corn silo on my great aunt's farm. He avoided/hated children but tolerated the adults who worked there. Depending on the season, he killed multiple mice a day, ate only their livers (leaving behind a trail of bodies), and used crippled mice to track down the hidden others. Tom was a true professional—and honestly, quite terrifying.
Edit: My aunt "paid" him with leftover spaghetti, ground meat, and eggs, as well as a warm spot by the oven in the winter (if he chose to stay there). He was "semi-feral"—never going near the house during the summer months.
We had an indoor/outdoor cat growing up that liked to hunt squirrels. He was so good at it that the squirrels had a special cry for him. Anyways, he liked to leave nothing but their heads (with spine and tail still attached) on our front door step. I miss the little serial killer