Bilingual vocalization in a Neotropical warbler

Abstract

Most birds, including songbirds, produce distinct, species-specific songs and calls. Here, I report on an individual bird of the Neotropical warbler genus Myiothlypis that produced vocalizations typical of two congeneric species. The “bilingual” bird, observed in the Serra dos Cocais region of Sao Paulo state, Brazil, appeared visually to be a White-browed Warbler (Myiothlypis leucoblephara) but was documented emitting songs and calls of that species and of Flavescent Warbler (Myiothlypis flaveola). Two possible explanations, not mutually exclusive, are raised and discussed, i.e., (i) hybridization between the two species, previously undocumented, and (ii) vocal imitation of both species assimilated into its vocal repertoire.