We describe a photodocumented field observation in Sinaloa, Mexico, of a head-down (or “preening invitation”) display performed by a male Bronzed Cowbird (Molothrus aeneus), which elicited both grooming and pecking responses from a female Great-tailed Grackle (Quiscalus mexicanus). Previously, such displays by parasitic cowbirds and responses by conspecific or various heterospecific bird species have been documented mainly under aviary conditions; most field observations have involved Brown-headed (M. ater) and Shiny (M. bonariensis) cowbirds. The function and evolutionary significance of such interspecific interactions remain elusive, but continued documentation of such occurrences may help elucidate their biological significance.