sentences:  In flight, it looks paler underneath than barn swallow.Six subspecies of barn swallow are generally recognised.In eastern Asia, a number of additional or alternative forms have been proposed, including "saturata" by Robert Ridgway in 1883, "kamtschatica" by Benedykt Dybowski in 1883, "ambigua" by Erwin Stresemann and "mandschurica" by Wilhelm Meise in 1934.