This is a neat little list, Thanks!
I had no idea about spinach and avocado being unsafe for ducks. My ducks (and turkeys) absolutely LOVE spinach, it's by far their favorite treat! They have been getting it about 3 days a week on average, never very much though, just the scraps from my salad fixings. Cilantro is a very close second place in their favorites, too, so that can be added to your list. They haven't touched avocado when I've given it to them in the past, though, so they must know about it.
***One thing I'm not so sure about, though - I think it's a TERRIBLE idea to feed any non-mammal ANY milk product!!! Especially pasteurized dairy, which is what I'm sure is in all your 'fridges. Pasteurized dairy is not even good for human consumption, since it's had almost all of the beneficial ingredients cooked out of it, including the enzymes necessary for properly digesting it. So the idea of feeding it to a non-mammal is something I find unbelievably foolish. Yes, it may have calcium and protein, but it's in the most foreign and indigestible form possible when in pasteurized dairy! Also, do you really want your birds to ingest bovine growth hormones, even in small doses? There are dozens of other foods to feed to ensure proper protein and calcium is in their diet. ***Please, please, please reconsider the idea of feeding dairy products to birds!!!
