- Birds may roost or nest in buildings, often gaining access through broken tiles and damaged ridge capping. This is usually a seasonal occurrence when birds are about to lay eggs, Pigeons, starlings and Indian myna birds are frequent offenders. Some birds nest in situations such as guttering and down piping which then causes water overflow and moisture problems in walls. Their faeces also reduces the normal flow of water in guttering, causing corrosion some types of metal guttering. The main offenders here are starlings and pigeons.
- A food poisoning bacterium (salmonella) can be contracted by humans from bird droppings. Several birds can be offenders in this regard.