In August these immature wood ducks (Aix sponsa) were swimming on Baum Lake (Shasta County CA). I wondered if they were all related or not.
Two or more broods may combine. Additionally, intraspecific brood parasitism, or egg dumping, is common among wood ducks. Female wood ducks often lay eggs in the nest cavities of other wood ducks and leave the brooding and raising of the chicks to the other female. Usually a clutch contains 10 or 11 eggs. However, because of brood parasitism nests can contain 30 or more eggs.
Chicks have a full coat of down upon hatching. Wood duck chicks leave the nest the morning after they hatch. The female tends the young for 5 to 6 weeks after they leave the nest. In 8 or 9 weeks the immature wood ducks are ready to fly.
These young ducks have about a month before beginning their first migration in late September.
The pictured wood ducks may all be full brothers and sisters. Or, because of intraspecific brood parasitism and/or immature ducks joining together in a group, they may not all be related. It is fun to speculate.