Black-headed duck


The black-headed duck is a South American duck allied to the stiff-tailed ducks in the tribe Oxyurini of the family Anatidae. It is the only member of the genus Heteronetta.

Description

This is the most basal living member of its subfamily, and it lacks the stiff tail and swollen bill of its relatives. Overall much resembling a fairly typical diving duck, its plumage and other peculiarities indicate it is not a very close relative of these, but rather the product of convergent evolution in the ancestors of the stiff-tailed ducks. 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.

Distribution and habitat

They live in swamps, lakes and marshes in central Chile, Paraguay, Uruguay, northern Argentina and southern Brazil, feeding by dabbling on water plants and insects.

Breeding

The black-headed duck is an obligate brood parasite, meaning the female does not build a nest. It lays its eggs in the nests of other birds, instead, earning it the nickname cuckoo duck. The hosts are particularly rosy-billed pochard, other ducks, coots, and occasionally even gulls and birds of prey. Unlike some cuckoos, neither the chicks nor adults destroy the eggs or kill the chicks of the host. Instead, after a 21-day incubation, the ducklings fledge and after a few hours are completely independent, leaving their broodmates and fending for themselves. In contrast with the brood parasitic passerines, whose young are altricial, black-headed duck ducklings are precocial.
The black-headed duck is not considered threatened by the IUCN.