The best time to feed wildbirds is after a fire, such as the wildfires in the California forests and desert hills, or in the winter when natural supplies are low. Hold back on feeding when the bugs start returning and flowers are blooming to help birds resort to their natural nutrients. One way to attract birds like hummingbirds and song birds is to plant the flowers or foliage they naturally feed upon. You can also supply feeders in the areas when the flowers will bloom so the birds find your area.
Never feed wild ducks processed breads, it seems like fun for the grandkids...but there is no nutrient value in bread for wild fowl and they will rely on this "junkfood" and not search for bugs and natural nutrients they need to survive.