Not just birds
One engineering firm I worked for was located in 'spare' farm buildings. This 'farm' was a major agribusiness and had massive grain stores, under which there was a complex network of pipes to blast air up through the floor to dry the grain. The dryer system itself was located in a specially built blockhouse with all sorts of safety features built in, including a large wire cage over the air intake - something like a 2M cube. When the system started up it sounded like a plane taking off. First auxiliary fans were started up on a standard star-delta time switch, then once the pressure reached a certain level the main fans were started by a massive contactor block - none of this was enclosed, after all nobody could be there on powerup. Only, one day there was a hell of a racket, then everything went quiet. Panicked farmers came running over to us for help. Our most experienced guy happened to be in the office so he went over to investigate. Apparently the main fan motor was still smoking (but amazingly survived) and the contactor block had one pole completely burned away. There were mouse droppings all over the place, and the guess was that some had dropped between the contacts of that pole causing it to arc.
Oh, and those farmers were not exactly poor. They paid for a new contactor block to be sent over from Germany by courier within 24 hours.
Biting the hand that feeds IT
