I found that squirrels are pretty smart too. I bought the big rat traps to get some that were in my mom's attic at one point. Baited them with peanut butter and set them. Next day we went and checked. The traps were sprung and peanut butter eaten. One trap was completely missing with no body evident. There was nothing to show how they did it. Buggers are smart. For mice, I like the battery operated traps best. I used them in the barn and zapped many mice. I even had one with two bodies in it one time. You would think they would know if they have to crawl over a dead friend that bad news is coming but nope. Second mouse crawled over dead buddy and stepped on the plate. ZAP! no more mousie.