Hi! If I had no access to 'chick starter', I would offer new ducklings a mix of cooked oatmeal, chopped hardboiled eggs, chopped greens.
Good luck!
Lisa
Mealworms would also be great to feed the ducklings! If I had no access to starter crumbles I'd try to mimic what ducklings would get in the wild with their momma: greens and insects.
They do need niacin. Try googling "feed store". There has to be something even NYC has livestock feed available. Even if you have to drive a bit, I think it would be worth it. I considered mixing my own feed but in order to have a "balanced" feed there are alot of components.
Just a question, where did you get your ducklings if you are not in an area with feed stores?