On a related note, brown rats make excellent pets, just so long as you don't let them breed and have your own population problems. I guess it's no surprise they're as prolific as they are, when they're probably the smartest small mammal out there and incredibly resilient to just about everything at that. My own rats answer to names and can perform simple tricks, sort of miles ahead intellectually than any other animal their size. They're also very loving animals, once they get to know you.