I'm guessing the stranded chicks were under the impression the people were their family? I always found it interesting when a baby animal is raised by a different species from a very young age. I wonder at what point they start to wonder why they can't communicate effectively etc. For example, if an orphaned donkey was raised in a herd of cows. A point for ducks. I wonder if you got lucky with the ducks, I've read many aren't all too friendly.
The chicks (one a feral game chicken mix of some sort, the other a Seabright mix) definitely thought we were their family. One didn't last past adolescence as my dad put him with some massive chicks he'd gotten in his very brief attempt at raising meat chickens thinking my JJ would be a good surrogate for the little monsters. They smothered him while attempting to crowd under him to sleep one night. Sooo much anger.

Both of these chickens were anomalies for their breeds. Both come from flighty, high-strung, wildish stock. Being handled extensively and kept from other birds until they were bigger resulted in very human-friendly birds. The same would likely be true of ducks. The down side would be potential aggression towards or from their own species.
The ducks were Pekings or a mix. Like chickens, duck friendliness depends a lot on breed and upbringing. Pekings are friendly enough already but being hand raised from day one, like my chicks, resulted in animals who didn't give a hoot what others of their species were doing, the humans were more interesting. They were spoiled rotten for it.
Needs were always met so communication wasn't really an issue. But like you, I wonder how a donkey raised by cows would feel as he got older!