Many of us have probably seen barn swallows starting to build their nests close to structures, but some of us may not appreciate their presence. Originally swallows were cave breeders, but now most build nest on human-made structures.
Barn swallows typically nest multiple times throughout the summer and have a 14 day gestation period before the eggs hatch. Then 2 to 3 weeks later the birds will fly the nest. The birds feed on flying insects and nest under overhangs. Barn Swallow parents sometimes get help from other birds to feed their young. These “helpers at the nest” are usually older siblings from previous clutches, but unrelated juveniles may help as well.
The nests are like an open cup of mud and grass and need to be protected from moisture since there isn’t any way to shed moisture or water. This is why nests are found very close to the ceilings. It prevents moisture from blowing in, and keeps predators out.
There are no easy means to controlling barn swallows. It is hard to frighten the birds, and there are no chemical repellents or sounds that work to discourage nest building either. Toxicants are not allowed and neither is shooting. In the United States, all swallows are classified as migratory insectivorous birds under the Migratory Bird Treaty Act of 1918. Swallows are also protected by state regulations. However, generally the Fish and Wildlife Service allows removal of nests prior to eggs being present without requiring a depredation permit.
Many of us may appreciate the insect control these birds provide but don’t necessarily care for the dropping these birds leave behind. However, nest removal is allowed before eggs are present. The best way to prevent barn swallows on your structures is to change the structure itself so that the nests won’t stick. Another option is to put up netting where you don’t want them. Plastic net or poultry wire can provide a physical barrier between swallows and a nest site. Mesh size should be about 3/4 inch (1.9 cm); however, 1-inch (2.5-cm) mesh has been used successfully. If plastic net is used, it should be taut to reduce flapping in the wind, which looks unsightly and results in tangles or breakage at mounting points. Do not use mist net or any other thin, flexible net with loose pockets or wrinkles that could trap or entangle swallows. For best results, install net or poultry wire before the swallows arrive. It may be left up permanently or removed after the nesting season. Barn swallows frequently enter buildings through doors or other open entryways and nest inside among the rafters. In some instances, simply closing the entrance or blocking it with net or wire is practical and effective.
Keep in mind that swallows are a very important part of our ecological system, and may be doing more good by consuming flying insects, than the harm of droppings.
