Laying in bed last night, and we heard these strange fluttering/scratching noises over head, tried to ignore it but it caried on, so at around 2am me and Mrs wife were there, both naked in the loft with a torch. Dont those rungs on a ladder hurt your feet when you have no shoes on? 
Never found anything, no droppings, no....well, no anything. Any sugestions?
My suggestion is.........

put something on feet before climbing a ladder cos yes it does hurt (a lot)
Hope this helps