I present the first published record of a foraging association between Nearctic-neotropical migrant bird species during the austral summer in South America. I observed Barn Swallows (Hirundo rustica) and Cliff Swallows (Petrochelidon pyrrhonota) in February 2005 repeatedly foraging on aerial insects flushed by flocks of Bobolinks (Dolichonyx oryzivorous) settling onto soybean plants (Glycine max). Additional observations would be needed to distinguish this behavior between an opportunistic association and a commensal relationship.