"Pigeon Droppings are damaging to our structures because they are acidic and have other compounds that can dissolve especially things like concrete," said Patricia Martinek, the agency's environmental research manager.

With its large quantities of bacteria and highly corrosive uric acid, pigeon excrement is partly responsible for disasters such as this bridge collapse, as well as the damage of concrete and countless historical stone structures.

According to Venice's department of fine arts and historic monuments, pigeons cause the most damage "to plaster and stucco used on the exterior of buildings and the mortar used in restoration work".