Because barn swallow nests can be unsightly and can create cleanliness and health issues for humans, they are sometimes removed as a nuisance.
Some humans feel that barn swallow nests are a nuisance, and are unsightly when they are attached to buildings and other man-made structures. Large colonies in urban areas can also create detrimental cleanliness and health issues for humans. Finally, salmonella can be transmitted through barn swallow feces, posing a threat to livestock that live in close proximity to barn swallow colonies.
As such, barn swallow nests are sometimes removed as a nuisance.