An Unsolved Mystery - Ducks Wait to Molt

Goose parents molt their flight feathers with their young, but ducks don’t.

Geese retain their flight feathers until their young are half grown then parent drop all their flight feathers. Yes, flightless kids and parents walk everywhere.

In the top picture you see a parent with primaries extending over the tail.

In the middle picture there are 4 much older goslings and 2 adults that clearly lack any flight feathers. The adults, like the kids, are growing new feathers, but nobody will be able to fly for another 25 days. The kids first fly at 65-70 days of age for our local big geese.

The bottom photo shows a hen BWT (left) with 2 of her 9 young. Note she has primaries and can still fly. Why not molt with the kids like geese? I’m stumped.

Frank