mysterious elf

I seem to have an elf living in my house. I can tell because he likes to leave piles of my tree decorations lying around. He puts piles of the stars on the couch and leaves some behind the tree as well. Sometimes he strikes four times a day. I have yet to catch him in the act. He is very sneaky. It's ok though, whenever I start putting them back on the tree Gabe is right by my side to help.