Pigeons May Have Been Factor in Bridge Collapse

I know these flying rats would eventually cause grief for mankind.

Pigeon droppings contain ammonia and acids, said chemist Neal
Langerman, an officer with the health and safety division of the American
Chemical Society. If the dung isn't washed away, it dries out and turns into a
concentrated salt. When water gets in and combines with the salt and ammonia, it creates small electrochemical reactions that rust the steel underneath.

"Every time you get a little bit of moisture there, you wind up
having a little bit of electrochemistry occurring and you wind up with
corrosion," said Langerman. "Over a long term, it might in fact cause structural
weaknesses."

They needed to put those little spikes on the bridge so that these little vermin don't land on the bridge and rust the supports with their crap. It would be a sad deal to die because of pigeon poop.