Birds might be nice, if not for the mess they leave. When they roost in an area, they leave behind feathers and nesting material, fleas and mites, and of course, most of all, they leave a lot of droppings. These droppings are not only unsightly, they're caustic and they're also unsanitary. The droppings of these problem makers are high in nitrogen, and can grow fungus. People can inhale the fungal spores and contract the lung disease histoplasmosis. When birds live in attics or ductwork, the problem is more likely to occur. Birds can quickly become a real nuisance. They produce filthy feces, waste and stink; in addition to what the nuisance birds are doing to the cosmetic appearance of your home or building.