This sort of thing absolutely happens without food rewards. I’ve been around keas, and they are - as @euansmith noted above - the goats of the air. They chew anything; worse than husky pups. Bike tires, car plastic fittings, window trim, you name it. Smart, curious, and with strong beaks is a bad combination in a nearby bird if you don’t want your stuff broken.
They’re also a protected species, and have less fear of humans than cats.
