Tachycineta thalassina

This species was originally named Hirundo thalassinus. Three subspecies are recognized: Tachycineta thalassina lepida breeds from Alaska and southwest Alberta to central Baja California and southern New Mexico, T. t. thalassina breeds on the Mexican plateau from southern Chihuahua to Oaxaca and Veracruz (but not on the east coast) and T. t. brachyptera breeds in Baja California and the coastal plain of southern Sonora (Brown et al. 1992). The distinction between lepida and thalassina is questionable (Brown et al. 1992). See Sheldon and Winkler (1993) for information on intergeneric phylogenetic relationships of Hirundinidae based on DNA.

Large breeding range in North America; large and relatively stable population size; no major threats.

Breeding range extends from the Yukon River valley in Alaska and central Yukon Territory and southwestern Alberta south through southern Alaska, British Columbia, southwestern Saskatchewan, Montana, southwestern South Dakota, and northwestern Nebraska to southern Baja California and the northern mainland of Mexico, and through Colorado and western Texas (Bent 1942, Brown et al. 1992, Sinclair et al. 2003). Recent range extensions have been reported in the northeastern part of range (e.g., Saskatchewan, Canada; Wright 1992, Houston 1999). During the nonbreeding season, the range extends from central coastal and southern California and Mexico south regularly to Honduras, casually or accidentally to western Panama and Costa Rica (Terres 1980, AOU 1983, Stiles and Skutch 1989, Brown et al. 1992).

This species is represented by a large number of occurrences (subpopulations).

On a range-wide scale, no major threats are known. Locally, threats may include introduced nest-site competitors, nesting habitat loss, and extreme weather conditions. Introduced secondary cavity nesters, including the house sparrow and European starling, threaten nesting success by competing for suitable nesting cavities; these species often begin nesting prior to the violet-green swallow, so they have an advantage in site selection (Bent 1942, Erskine 1979, Brown et al. 1992). Removal of snags may have a strong negative impact on the species. In northern Arizona's ponderosa pine forests, this species was exclusively reliant on snags for nest-site locations (Cunningham et al. 1980, Brawn and Balda 1988). Clearing of forest for settlement and agriculture removes natural nest sites, as do forest harvest strategies that remove snags (Erskine 1979, Brawn and Balda 1988). This species is sensitive to extremely cold weather and accompanying low insect activity; large numbers of individuals have been found dead in emaciated condition after spring storms along migration routes (Bent 1942).