Elephants in the roof

Over the last couple of days, I've become aware that there is something living inside my roof. At first I thought it was a mouse, then I decided it sounded more like a bird. At five in the morning, though, it sounds more like a large cat. And it seems to get louder (and thus sounds larger) every night.

I'm going to put rattex or something up there, but I have to work up the courage first - I'm afraid that if I open the trapdoor a baby elephant might jump out at me.