Right now, here in North America, we have, generally speaking, a maximum number of young, inexperienced wild animals around. And, there is, all being equal, a maximum amount of naturally occurring food for them. But, we are entering the fall: a prelude to a sharp decline in food availability for most of them. That's how it works. But, soon, winter will arrive.
Too many myths and conflicting values exist to be covered here, regarding the question of whether or not we should feed wildlife, but the subject is worth a bit of consideration. (And read my Q&A; about feeding birds here.)
Let's start with ducks. Feeding bread to ducks is a bad idea. Some argue that it causes "angel wing," which is not entirely so. Angel wing is a poorly understood condition whereby the wing of the bird (usually, but not always, a duck or goose) twists outward from the "wrist" joint. It's thought to be caused, at least in part, by bad nutrition. Bread provides inadequate nutrition and thus may be a contributing factor - but angel wing has been found in birds who either don't eat bread, or were known to not have ever fed on it. On the other hand, angel wing seems to appear more where birds are fed highly processed food, such as bread and popcorn. It is highly advised that, if you do feed local waterfowl, you give them good quality natural grains. Avoid anything moldy.