In you attic it could be Flying Squirrels, usualy the size of chipmunks.
They are common in USA but you rarely see them as they are nocturnal, If
you hear them at night and hear chewing on wood it could be them. They
can enter any little hole in your eaves, overhang, facia,. I have them.
I threw up moth balls they do not like them, yesterday I found a hole ,
because mothballs were on the ground. Those critters are REMOVING them
one by one, problem is they only go out at night so if I seal a hole in
daytime I seal them in and they will just chew open another hole. So im
just throwing in more Mothballs today, Ive been fighting them for years,
remember it is their house, they want in.