“ Rats laugh at bucket traps, here in Pa. They can swim better than mice, too”
You didn’t leave them in there long enough.
I’m a serial buyer of distressed properties. A lot of them have rats and I’ve learned you need a pretty tall “bucket” to trap a rat and drown it. Also they tend not to go into such traps, but one thing that seems to fool them is perlite on the surface of the water — it looks like a solid surface so they might jump down to it if the bait is appealing. So a typical outdoor trash can with at least a foot of water in it, a layer of perlite, some leaves, and bait — will sometimes yield a dead rat.
But pretty soon the rest of the rats catch on, and eventually you need a screen to separate the perlite from the water, and a sewer to dump the water...it does get stinky.
Mice are small and comparatively stupid. Most any method will get you dead mice.
It’s also helpful to provide the rats with a lot of free lunches. No water under the perlite for a while. When they regularly frequent a site for the grapes and nuts you leave for them, they’re not only comfortable with the setting, they trust the bait and maybe they let their guard down. Maybe. :(