It's mostly common sense.  You have to think of what rogue squirrels really are - intruders, criminals and disease carrying vermin.  As I try and project on my squirrel pages, you can think of these interlopers as "criminals of the squirrel sect."  Instead of 'doing what comes naturally,' they have invaded our personal domain.  And in addition to not paying any rent, they can do any one or all of the following: compromise our health and security by carrying diseases, soil our attics, walls or crawlspaces, and chew electric or alarm wiring. I put it this way.  Would you catch an obvious and confirmed criminal in one town, and then just go and release him in another?  I think not.  (Or at least we TRY not to do this in our society.)  It's just as bad (maybe worse) that we do this with rogue squirrels.   Understandably, this is not all the fault of the squirrel....  Man, by the careless way we store and manage our trash, agricultural and food stores, merely INVITES the squirrel to dinner.  Sometimes it's actually dinner!  Many well-intentioned people actually FEED the squirrels, which only acclimates them to humans, bringing them in close proximity to your house.  As opposed to when you're in the woods, hunting squirrels in a wooded and non-residential area, squirrels HIDE from you, by cleverly staying out of both sight and range.  You can go through a setting like that without seeing a squirrel within a hundred yards.  Yet, they are as populous as they are around you.  Maybe even more so.  Definitely a challenging hunting target.  I know, I've done it. The population of squirrels, increasing as they have, has forced them into places they normally would not go.  Couple this with the way houses "age," it creates a multitude of places the squirrels can use that are better than the hollow tree they get in the wild. They may look cute, but they can be as bad or worse than rats. Since they are the ultimate scavenger, the so-called wolf in sheep's clothing, and are able to ‘leap tall buildings in a single bound,' they will cover virtually every square inch of the outdoor environment.  Those squirrels will investigate and discover any flaws that allow them to inspect the inside of your house.  And just as they do on the ground, in the attic they'll stay conveniently out of reach and they'll also stick around.  After that, the either oblivious and/or co-operating homeowners allow these invaders to breed inside, sending forth a regular bevy of naturally-made rogue squirrels into the neighborhood.  I've seen it happen hundreds of times. If everyone left them alone, never fed them, (nor any wild animal) our squirrel problems would be minimal.  Naturally, there would still be invasions - this is the consummate suburban ‘predator' to our suburban home. So while I understand the ‘compassion' that people feel for animals, and even the common habit of even ‘putting out the spiders' without killing them, we have to watch out that we don't turn our own innate human altruism into the assumption that animals have actual ‘human' qualities.  And certainly not these squirrels or the other animals that prefer to invade our buildings.