Evidence of multiple clutches for the Barn Swallow (Hirundo rustica erythrogaster, Passeriformes: Hirundinidae) in central Argentina

Abstract

The Barn Swallow (Hirundo rustica erythrogaster) is a migratory bird widely distributed in the American continent, breeding in the Northern Hemisphere and, since 1980, in the Southern Hemisphere as well. The average clutch size is between four and five eggs. In the present study we report unusual clutch sizes in nests of the species in central Argentina, we also carried out a bibliographic review of studies on reproductive biology of the species where clutch sizes are reported, and we analyzed the possible causes of those exceptional clutches. The study was carried out during the reproductive season 2016/17, near the city of Santa Rosa, La Pampa, Argentina. Our results show the first record of a clutches of 10 and 9 eggs for the species in South America and the second worldwide. Although breeding on the nest was not intensively monitored both indicated that they were multiple clutches.