I'm sorry to report that baby bird didn't make it.
Although the parents were still diligently bringing it food, and it was peppy and happy and eating, last night I found baby bird had once again plummeted out of the nest near the back door again. This time its landing must have injured it, because it was showing definite signs of something seriously wrong.
I knew when I first saved it that its chances were slim to none. All of its brothers and sisters were HUGE fledglings, and baby bird was tiny. It looked as though it was a good week behind its siblings, and whether that was because it was a late hatcher, or because of some medical issue, it didn't really matter, it really didn't stand a chance.
I was torn between trying to hand raise it (and I would have if I thought it had a chance), or letting nature takes its sometimes cruel course, and opted for nature. I put baby bird back in the nest, where I was sure it would at least be comforted with its natural surroundings during its final time.
This morning I climbed the ladder and found what I expected. I removed baby bird, nest and all, said a few words for it, and disposed of it properly.
I hope its happily swooping around across the Rainbow Bridge.