what if litter (a plastic shopping bag) were to randomly blow onto the head of a statue? Did mother earth "deface" that statue?

There is alot of commercial litter on the streets in public parks etc. Is litter vandalism? I saw a paper napkin with a dunkin donuts logo on it blowing onto the sign of an MT bank. Isnt that vandslism? I know it blocked the m & t from sight. Empty bank wasnt a great message anyway. Was it vandalism or improvement?