The cliff swallow, 5 to 6 inches (13 to 15 cm) in length, is the only square-tailed swallow in most of North America. It is recognized by a pale, orange-brown rump, white forehead, dark, rust-colored throat, and steel-blue crown and back. The cave swallow is similar in appearance, but has a rust-colored forehead and pale throat; it is restricted to southeast New Mexico and central, south, and west Texas.
The barn swallow, 5 3/4 to 7 3/4 inches (15 to 20 cm) in length, is the only swallow in the United States with a long, deeply forked tail. Barn swallows have steel-blue plumage on the crown, wings, back, and tail. The forehead, throat, breast, and abdomen are rust colored. Females are usually duller colored than the males.
Cliff and barn swallows are found throughout most of North America. Breeding occurs northward to Alaska and the Yukon, across Canada, throughout the western United States, and south into Mexico. Barn swallows are common nesters in most of the southern United States, except Florida. Until recently, cliff swallows did not breed in the southern United States east of central Texas and south of west-central Tennessee or western Kentucky. Reports of new colonies in eastern Tennessee, Louisiana, Alabama, Arkansas, Mississippi, and Florida suggest a range expansion into the southern Atlantic seaboard and Gulf Coast states. Barn swallows are also found in Europe, North Africa, and Asia.
Barn and cliff swallows regularly build mud nests attached to buildings and other structures, a habit that sometimes puts them into conflict with humans. This is particularly true of the cliff swallow, which nests in large colonies of up to several hundred pairs. Barn swallows tend to nest as single pairs or occasionally in loose colonies of a few pairs. Some homeowners consider barn swallows to be at most a minor nuisance.
Swallows have a tendency to nest in previous nesting sites.
Cliff swallows will prematurely desert their nests en masse, leaving their young to starve, when swallow bug populations become too great.
Cliff swallow nests are gourd-shaped, enclosed structures with an entrance tunnel that opens downward. A typical cliff swallow nest contains 900 to 1400 pellets, each representing one trip to and from the nest.
Barn swallow nests are cup-shaped rather than gourd-shaped, and the mud pellets contain coarse organic matter such as grass stems, horse hairs, and feathers.
Cliff swallows nest in colonies and often live in close association with humans. 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. 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.
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.
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.
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.
Netting or wire mesh. Strip doors.
Substrate modification: slick surfaces discourage nesting.
Architectural design: some designs discourage nesting.
Avoid overhanging eaves.
Not effective for barn or cliff swallows.
None are registered.
Wash nests down with a water hose or knock down with a pole.
The above information was adapted from PREVENTION AND CONTROL OF WILDLIFE DAMAGE with permission of the editors, Scott E. Hygnstrom, Robert M. Timm, and Gary E. Larson (Cooperative Extension Division, Institute of Agriculture and Natural Resources University of Nebraska-Lincoln, United States Department of Agriculture Animal and Plant Health Inspection Service, Animal Damage Control, Great Plains Agricultural Council Wildlife Committee).