My specific question is....what can I do (if anything) to protect my black metal railings from bird poop stains? I can deal with scrubbing off the poop with a strong brush and hot water with a smidgen of bleach, but am concerned the poops might leave an actual stain on the black railings.

Maybe apply some type of an oil to the railing tops to no only discourage perching there, but to help create a protective barrier for any bird poops?

Tx!