Some birds, like pigeons, have corrosive acids in their droppings that can eat away at concrete. This can cause damage to buildings and walkways, and deface statues--quite literally.
All birds have the potential to carry disease in their excrement, but common pest birds like the sparrow, starling, and pigeon, which eat from dirty dumpsters and trash heaps, are more of a vector for illness. This makes pest birds especially dangerous to employees who have to clean infested areas that are in enclosed spaces. Make sure all maintenance personnel wear masks, protective clothing and take all appropriate precautions when dealing with these issues.
When birds leave their droppings on walkways, they can be a slipping hazard for employees and customers alike. This can lead to workman's compensation claims and lawsuits.
Cleaning the feces that birds leave behind also has an economic impact on businesses in terms of water, electricity, and manpower costs.
Air conditioning units and outside machinery can be extensively damaged when birds accidentally fly into moving parts.
Some birds prefer to nest in electrical boxes. This has the potential to cause a fire.
Birds resting on wires can lead to power outages.
When birds get into man-made structures they can damage rooflines.
Feral chickens can be quite a nuisance to a business with their constant clucking and crowing.
When birds get into wall voids their thumping and scraping can be quite a distraction
When birds get into air ducts, the harmful bacteria and disease from their droppings can become airborne inside a business.
When birds move from trash and sewers to areas where fish or livestock are being culled, this can lead to health risks.