Parasitismo de puesta facultativo por un zorzal Turdus migratorius en el nido del maullador Dumetella carolinensis

Avian brood parasites can be classified as either obligate or facultative. Obligate brood parasites, such as Brown-headed Cowbirds (Molothrus ater), must lay their eggs in the nests of other species because they exhibit no parental care. Although facultative brood parasitism, when species that would normally lay eggs in their own nests dump eggs in the nest of another individual, may occur frequently among conspecifics, facultative interspecific brood parasitism is relatively rare. Here I report on observations made during the breeding season of 2018 of an example of facultative brood parasitism by an American Robin (Turdus migratorius) in the nest of a Gray Catbird (Dumetella carolinensis). Two robin eggs were laid in the nest of the catbird and were successfully raised by the catbird to fledging age. Although the young of obligate brood parasitic cowbirds are rarely raised successfully by catbirds, this is the first documented example, of which I am aware, of a Gray Catbird successfully raising the young of a facultative brood parasite.