If you have crows, it probably is them!! They seem to love messing in my semp beds, and they sit and watch me working in it, and I know they're waiting for me to leave (I don't live there, so I really do have to leave at some point) and then next time I go there - sure enough several semps moved around...mostly they seem to mess with the same couple of semps so I just think its "cute"
I love when I'm visiting somewhere and the person decides they need to get rid of a NOID and everyone else around is either not interested or too shy to speak up!! Sorry ladies - I'm not shy when it comes to semps!