Bird nests on the balconies are a sanitary nuisance
Keep an eye on the balcony so that no birds build nests there. The birds litter and are a sanitary nuisance to you and your neighbors around you. In addition to littering, birds can carry diseases.
If you have had a bird's nest before, there is a great risk that the same pair of birds will return year after year. The droppings can corrode the facade and balcony floor.