Birds such as pigeons, starlings, sparrows carry bugs and deadly diseases such as bird mites, blastoplasmosis and histoplasmosis. Bird droppings have a high content of nitrogen which is highly corrosive and creates stains on walls and floors that are very costly to remove. Humans can contract respiratory problems from breathing infectious dust transmitted through ventilation systems, such as air conditioners, created from birds.
Birds produce millions of dollar in crop and property damage each year. When birds get into grain bins, warehouses and grocery stores the can contaminate food and cause an unsightly mess from nesting material and bird waste left behind. Birds do not make holes in buildings, but they will enter a structure if they can find a hole. Once in they can build large nest that over time can collect moisture that will lead to wood rot and structural failure or even cause a fire.