Last summer I recounted my tale of caring for two fledgling Robins until they could fly. I was helped by the birds' parents, who came often to feed the babies (I fed them too). In less than a week they were strong enough to fly away.
This morning, as I was sitting at the table underneath my canvas patio cover, I heard a "Plop" and looked to my right to see a young sparrow on the patio, looking stunned. He seems to have just fallen out of the sky, or perhaps from a nest on my roof, invisible to me. I immediately fetched him and put him in my bird cage to protect him. Then I read about the feed and caring of fledgling Sparrows via a Google search.
I learned that fledgling Sparrows have a high mortality rate when in held captivity. Some informed wild life rehabilitators stated that the fledglings are best left on the ground, because their parents will continue feeding them until they can fly. So I freed the baby bird. He immediately took refuge under a big bush in the corner of my yard. In about fifteen minutes, an adult sparrow showed up and began feeding him.
I think the bird will be okay, absent any predators (like cats). In any case, I think I did the right thing.