Damage

Cliff swallow (Hirundo pyrrhonota) with nests on a building.

Cliff swallows nest in colonies and often live in close association with humans. Many swallow colonies on buildings and other structures are innocuous. In some situations, however, they can become a major nuisance, primarily because of the droppings they deposit. In such instances they may create aesthetic problems, foul machinery, and cause health hazards by contaminating foodstuffs. Their mud nests eventually fall to the ground and can cause similar problems. Parasites found in swallow nests, including swallow bugs, fleas, ticks, and mites, may bite humans and domestic animals, although these are not the usual hosts. In addition, cliff swallow nests are often used by house sparrows, introducing another avian pest and its attendant damage problems and potential health hazards. Barn swallows nesting singly or in small groups on a structure can cause similar problems but of a lesser magnitude due to the smaller numbers present.

Legal Status

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. It is illegal for any person to take, possess, transport, sell, or purchase swallows or their parts, such as feathers, nests, or eggs, without a permit. As a result, certain activities affecting swallows are subject to legal restrictions.

Permit Requirements

A depredation permit issued by the US Fish and Wildlife Service may be required to remove swallow nests. Three of seven administrative regions of the US Fish and Wildlife Service in the continental United States require a permit regardless of the time of year. This includes nests under construction, completed but empty nests, nests with eggs or young, or nests abandoned after the breeding season. Four of the seven regions do not require a permit if eggs or young birds are not present in the nest.

If eggs or nestlings are present, a permit authorizing nest removal or the use of exclusion techniques is required in every region and will be issued only if very compelling reasons exist. An example might be the safety hazard of a nesting colony located at an airport where aircraft safety is in question and where other methods of control are not applicable. In most cases (for example, swallows nesting on a residence or other building), a permit allowing lethal control will not be issued.

For permit requirements in your area, contact the closest US Fish and Wildlife regional office or USDA-APHIS-Wildlife Services district office. At the first sign of nest building, contact the appropriate authorities, since swallows can build their nests and lay eggs in a short time. Timing is critical in those regions that require a permit. If a swallow problem has been experienced in the past at a site and is expected to reoccur, then apply for a permit in advance of the birds’ return. A fee is charged for a permit.

Economics of Damage and Control

Costs of damage are difficult to quantify and vary with the particular site and the method of control employed. The cost of actual or potential damage can range from the cleanup of droppings on and around a structure, to thousands of dollars from swallows contaminating foodstuffs at a processing center or posing a danger to aircraft at an airport. Similarly, control costs vary greatly. When hosing is used, costs are primarily labor-related. Net is relatively inexpensive (from about $9 to $33 per 1,000 square feet depending on quantity purchased, 1992 prices) and is reported to be effective for 4 to 5 years before replacement is necessary. Labor and other equipment costs to install netting, however, can be quite high. For example, mounting net on a concrete versus a wooden structure, or 100 feet (30 m) versus 10 feet (3 m) above the ground can drastically increase costs. Costs for each site must be judged on an individual basis.