Black-headed Duck

The Black-headed Duck (Heteronetta atricapilla) is a South American duck allied to the stiff-tailed ducks in the subfamily Oxyurinae of the family Anatidae.

It is a small dark duck, the male with a black head and mantle and a paler flank and belly and the female pale brown overall. They live in swamps lakes and marshes in North Chile, Paraguay, and North Argentina, feeding by dabbling on water plants and insects.

The Black-headed Duck is of interest as an obligate brood parasite, laying its eggs in the nests of other ducks, particularly the Rosybill (Netta peposaca), and also in coot (Fulica species) and even gull nests. Unlike cuckoos and some other brood parasites neither the chicks nor adults destroy the eggs or kill the chicks of the host. Instead, after incubating for 21 days, they fledge after a few hours and are completely independent immediately.