We review the extralimital occurrence of Cave Swallows (Petrochelidon fulva) in the United States and Canada since the 1960s. Nineteen (29%) of 65 occurrences not associated with an incursion in late autumn 1999 have been verified with photographs or specimens. Spring specimens of the West Indian subspecies P. fulva fulva are from Alabama and Nova Scotia; the subspecies of a Cave Swallow salvaged in Mississippi in spring is uncertain. Autumn specimens of the southwestern subspecies P. fulva pallida are from North and South Carolina. Cave Swallows measured and photographed at Cliff Swallow (P. pyrrhonota) breeding colonies in Arizona and Nebraska were P. f. pallida, as well as one bird photographed at a Cliff and Barn Swallow (Hirundo rustica) colony in Louisiana along the Mississippi line. Photographs of Cave Swallows in spring at California and in late autumn at New York were P. f. pallida. Subspecies could not be determined for six other records verified by photographs. Most of 46 sight observations of Cave Swallows have been reported at similar locations, seasons, and times as the verified records. Extralimital Cave Swallows in the United States and Canada have occurred along the Atlantic and Gulf coasts and in the interior, especially during spring and late autumn, and extralimital occurrences in the 1999 incursion matched the pattern in other years. The majority of birds on the Gulf coast occurred before the 1990s, mainly in spring, and on the Atlantic coast and in the interior during the 1990s, mainly in late autumn. The pattern of extralimital occurrence is consistent with changes in the breeding and winter status of the two subspecies. In Texas, breeding and overwintering populations of P. f. pallida have rapidly increased since the mid 1980s, in contrast to the slight increase of breeding populations of P. f. fulva in southeastern Florida.
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Vol. 72 • No. 4