Male plumage mimicry by adult females of sexually dimorphic hummingbird species provides an intriguing system for understanding social and ecological selection mechanisms. However, our understanding of female male-mimicry is limited by a lack of behavioral observations of wild hummingbirds with male plumage, such as in giving parental care. Using photos and 2.5 min of video taken at close proximity, we documented a Veraguan mango (Anthracothorax veraguensis) with male plumage both incubating eggs and later feeding young in the town of Palmar Norte in southern Costa Rica. Based on plumage characteristics and range, we ruled out the similar green-breasted mango (A. prevostii) that occurs in close geographic proximity. Using Google Earth imagery, we characterized the landscape surrounding the nest as a heterogeneous mix of urban, residential, and agricultural land. We speculated on potential mechanisms that may maintain female-limited polymorphisms in the Veraguan mango and related species, including the interaction of social and ecological selection pressures. This observation provides the first empirical evidence of male-mimicry polymorphism in the Veraguan mango, contributing valuable information to the species’ natural history and to the broader understanding of male-plumaged females in hummingbirds.