The process of laying eggs in a host's nest to be incubated and after hatching to be raised is called parasitism. Fulvous Whistling-Ducks dump eggs occasionally, since they can also build nests and raise their ducklings. That is why this parasitism is known as facultative. Facultative parasitism is mostly found in anatids, where the process only requires incubation of the eggs since ducklings feed on their own.
At Costanera we have seen many Fulvous Whistling-Duck families grow. We do not know if they have been parasitized intraspecifically. But up to now (2016) we have had two cases of interspecific parasitism, being the host a Rosy-billed Pochard in the two cases.
© Roberto Ares