This has been an ongoing problem, and I've stumbled upon a technique that appears to be working consistently for my location in western PA. Rodents in other locations can be more of a threat, carrying the hanta (?) virus. I've read and heard a multitude of methods at trapping and preventing these fancy rats from invading shop and home space. These particular ones are the flying type, gliders actually. Yeah, they're cute, but nature belongs outdoors or not where I am. The NG alt.home.repair used to have lots of posts about rodents, friends have related their own mostly unsuccessful experiences, and have seen the Backyard Bandits shows the BBC made years ago. They're very agile and can be extremely clever.. it's said that they have map/memory intelligence to remember how to retrace their route to stored food.
Mice are fairly easy by comparison.. place a trap on their trail, and you'll get 'em, sometimes sideways as they attempt to run over the mouse trap. It seems like they're too busy playing tag or grabass and aren't the least bit cautious about where they run.
I won't consider poisons as an acceptable solution. The only thing worse than a filthy destructive rodent is smelling (and trying to locate) a stinkin' carcass.
The pyrotechnic technique shared here in RCM about a year ago seems a little (?) risky, although the video would probably make it worthwhile.
Preventing them from entering or quick death are the better solutions, I figure. It seems that it's possible that some of them have a preference for this structure, located on the wooded edge of a small town. Deer often visit for the crab apples (and maybe the chestnuts), and ground hogs are present near the back edge of the property. Large oaks are nearby, knot that I'm all that familiar with the trees of North America, but I've found caches of acorns in the shop.
A couple of seasons ago I got a couple of the large Victor traps and figured it wouldn't be very difficult to diminish the population to a point where there wouldn't be any left that had a preference for this building. I got a roll of hardware cloth to experiment with putting large amounts of aromatic bait inside a cage with the trap at the entrance (haven't tried that yet).
I dunno if litters have been born in this building, but they seem to be very familiar with the structure. I figured these bastards have great night vision, so I got some artist's charcoal sticks to blacken the big white board that the traps are built on. Stealth traps, black on top, sides and ends. Big tasty morsels that can't be removed.. sounds like a good plan.
I've witnessed them moving around while I was in the shop (located in the basement), and they use a ledge on top of the formed walls for a trail. The ledge is wide enough to hold the traps, and when the trap goes off, the traps fall off the ledge, so I tie a cord in the loop at the back of the trap (the staple that the arming lever is mounted with) and attach the cord nearby. This serves 2 purposes.. the trap won't fall behind something, and it removes the trap from that trail temporarily (which might limit their ability to remember a specific spot where a sibling died). This may sound weird, but there is one spot where I've gotten numerous kills (same trap, same nut).
After seeing that peanut butter, cheese and bacon weren't going to be effective (to my astonishment), I tried corn chips, Fritos.. aromatic and tasty, but no luck. I was still having a hard time believing that peanut butter wasn't effective. Early in the learning process, I nailed one with a piece of non-garlic ring balogna that had been on the trap so long that it was really stale and moldy. My usual mounting method was to wrap any bait with a heavy cotton thread to insure that some tugging and biting would be required.
Among the acorns I've found, there were a couple of larger white-shelled nuts, that a friend identified as hickory nuts. I cracked a couple of 'em open so that they might release more aroma, and noticed a white nut with red skin. I drilled a few holes thru the nuts and wired them to the trap triggers by threading the wire thru the holes and passing around the bottom of the triggers. The acorns mount well on mouse traps, same method.. crack 'em open, drill and wire to attach. It's said that the early bird gets the worm, but the second mouse gets the cheese. When the traps fall off the ledge, hanging in air, it's gonna get a little difficult for them.
The wired-on hickory nuts have been completely successful. No bother with reloading more bait.
WB