Sounds like the rattle scared them more than the cage itself, since woodpeckers use the noise to check for danger.

Burned my own hand the same way last year, except mine had a chip in the rim that I kept ignoring because it was my lucky mug. Turns out lucky mugs are not a real thing, or at least mine was not. I walked around the rest of that day smelling like a diner floor. Now I do the tap test too, just flick the rim with a fingernail and listen for a dull thud instead of a ring. Takes two seconds and saves a lot of grief.

Watched a guy on a bridge job in Pittsburgh lose a whole meatball sub to a red tailed hawk. Thing came down like a missile, grabbed it right off the rail where he set it down. He tried to chase it and almost walked off the edge. Crew still gives him hell about it ten years later.