Birds are always looking for the safest place for them and their flock to nest. In colder climates, this can mean that non-migratory birds will nest indoors.
This can mean nesting in warehouse department stores, food facilities, home attics, barns, wherever! Birds are looking for comfort and many times that means in warm cozy spaces inside.
Pest birds that congregate in indoor locations can cause damage to property with nesting, pecking, and droppings, disease spread, and are just frustrating to have around!