Spring migrants arrive 15-25 April and peak abundance occurs 25 April to 5 May. Fall migration begins in late July with gathering of family groups. Peak abundance occurs between 25 July and 10 August and departure by 1 September. Breeding Bird Survey data suggest that this species is the least common of the swallows nesting in the Valley. This exceptionally high density results from the numerous exposed limestone cliffs along that river, which provide abundant nesting sites. Particularly important are limestone cliffs along fast-moving streams and rivers in the Western Upland.
Occasional use is made of artificial earthen banks and bridges over small streams.
Regular migrant and nesting species. Peak fall abundance occurs 25 August to 10 September and departure by 10-15 October. Common nesting species in the Western Upland and Central Plain, uncommon and local in the Northern Highland. Most nests are found under bridges or on buildings. Regular migrant and nesting species.