Barn swallows are socially monogamous, but genetically polygamous, as extra-pair copulations are common.
Like all swallows, barn swallows are socially monogamous. However, extra-pair copulations are common, making this species genetically polygamous.
The barn swallow’s breeding season is usually from May to August, but this varies greatly with location. Breeding pairs form each spring after arrival on the breeding grounds. Pairs re-form each spring, though pairs that have nested together successfully may mate together for several years.
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• Sources | (BirdLife International, 2016; Bolzern, Moller, & Saino, 1997; Brown & Brown, 1999; De Lope & Moller, 1993; McWilliams, 2000; Moller, June 1994, July 1994, 1995; Perrins, 1989; Roth, 2002; Terres, 1991)