I have noticed on two separate occasions that when it was windy I have heard scratching outside one of our upstairs rooms. I assumed it was a bush that needed to be trimmed that was scratching up against the outside wall. When I went out I realized that there are no trees or bushes by this wall. We have vinyl siding, could the wind be causing the siding to make a scratching sound? Or do I need to be concerned about a critter in my wall?
Yep, vinyl's horrible stuff. It's very common for it to creak, rustle and pop with weather and Sun exposure. However, you may have some screws (suggested) or nails (loosen frequently) that are a little too-loose that should be easily re-done.
The siding can be quickly and easily zippered apart and the screws or nails reset or re-installed. The fasteners should only hold the siding snugly to the wall, but still allow the siding to slide side to side so it doesn't buckle or bow with temperature and Sun exposure changes.