Maybe Rickair, but the text accompanying the pictures mentions that the aircraft had been used on a fishing trip and then taken hunting. Guessing the salmon smell is what drew the bear(s) in for a look. I don't know if there was fish inside the plane or if it was residual smell that was so attractive. Betting that if there had been fish inside the damage would have been worse.
Plenty of tales of bears down around Yellowstone prying car doors open to get at camping food, don't know the accuracy of those but betting it's quite possible.
Find the pictures interesting because I'd heard of things like this happening with fabric covered airplanes but had never seen the results. Have been super careful with my Cub to minimize smelly stuff inside- to the point where I've carried salmon and deer meat in a double wrapping of garbage bags. One time when some fish slime leaked a bit I made a point of hosing the cub out with water when a sunny day rolled around.