Interspecific nest parasitism, or nest dumping, is when one species lays an egg in another’s nest. This occasionally occurs between Hooded Mergansers and Wood Ducks which share nesting habitat. When this happens, the foster mother will raise the duckling as her own. Studies have shown that in this unique situation, the affected duckling has an equal chance of survival as if it had been raised by its own species.
I had been sitting in a blind when a mixed family of five (four pictured) climbed up onto a log, an adult and three young Wood Ducks along with a single Hooded Merganser duckling. While I watched, the hen brooded each of the chicks as her own, not acknowledging any difference. Note also that the female has only one eye closed. Many birds are able to control their brain so that one side sleeps while the other is awake and alert. Ducks are low on the food chain and must always be on the lookout for predators. June 6, 2015