Record of the parasitism of Coryphospingus pileatus by Molothrus bonariensis (Aves, Passeriformes)

Molothrus bonariensis stands out as a generalist parasite with more than 200 recorded host birds. In the genus Coryphospingus, only C. cucullatus has been reported to be parasitized by shiny cowbird. This study sought to describe the behavior of C. pileatus in a nest observed in a residential area with a record of parasitism by M. bonariensis. The nest contained two eggs of C. pileatus and one egg of M. bonariensis. The Chopin chick was expelled from the nest on the second day, while the native chicks developed normally and left the nest seven days after our observations began. The study provides a new record of parasitism by M. bonariensis in the genus Coryphospingus, and the absence of antiparasitic measures suggests that C. pileatus is an accidental host of M. bonariensis and of low quality for parasitism.