Buy three or four Habanero chilis. Throw them in a blender with three or four cups of water and blend the hell out it. Filter out the particles with a coffee filter and put it into a spray bottle. Spray affected vegetation every couple of days.
BTW, wear gloves and safety glasses throughout the whole process and avoid windy days when spraying.
Used on a lawn, it was a great way to combat the irresponsible owners who allowed their dogs to use the front lawn as a toilet. And also took care of the rats the use to come around the bird feeders. Birds, IIRC, are not affected.
I’m afraid I agree with Dufus. The pack rats and mice were there first. Your bonsai trees, be they never so precious to you, are an unnatural, and tasty, introduction into the environment. And the poison is a deadly introduction, not just to the rats and mice. The really responsible thing to do is to concentrate your gardening energies into native plants that the local fauna doesn’t find appetizing.
Sorry, but the OP has taken more steps than the average person to be environmentally responsible. He has a desert landscape garden and he tried live trapping out of concern for the rats (how many people would do that?). If that’s not good enough for environmentalists, and rats, well, too bad. He has a right to live his life, too, and if that includes an appreciation for bonsais, in which I assume he’s invested a fair amount of time and money, I think he has every right to protect them considering the environmental steps he’s already taken.
Nothing a .30-30 can’t fix, though if you’re from the Klondike I don’t suppose you own anything that light. Be sure to get the internal temperature up to about 500F, just to be safe.
Or, the OP could get a cat of their own… even if you get a ‘lazy’ one that doesn’t chase rats/mice apparently the presence of a cat is enough to scare them off.
I don’t have a rat problem, so I couldn’t swear to it.
I can go one better, how about a bait tray laid on a piece of aluminum foil then laid on a cardboard box and when checking in the morning the tray and aluminum foil was gone never to be found. In a house no less! (The house we live in is aging and designed for the Carribean basically full of vent bricks but still.)
Don’t underestimate what a large rodent can carry.