It was alone when we found it. Yes, we went digging for worms. Also, it appears to have lost its tail feathers (1 left) by a fight or something else. Any suggestions on where to put it to rehabilitate (no not the backyard)? Currently the bird is in a box with a little paper. Also, how many worms?
It doesn't actually need its tail to remain flighted. If it's an adult, and has lost it's tail feathers, it should still be able to fly just fine without its tail. If it's lost them through trauma and cannot fly, it likely has more dire injuries than you've detected.
If it's a recently-fledged youngster (you can tell by the spots it'll have around its breast), it cannot fly well because that's how they start out. They leap from the nest, but don't fly far. They call a lot, and mom and pop answer them, and bring them food. Within a few days they'll strengthen to the point where they can get around just fine. If you remove them from the parents attention, it's very unlikely that the parents will re-adopt them. They cannot count, so probably won't really notice it's gone anyway. If the parents happened to see a large predator (you) in the vicinity of one of its now-missing young, well...
If it's any comfort, probably in the neighborhood of 80% of those little guys don't make it through their first year anyway. Many are the victims of predators at fledging-time (like has happened here), even though it's accidental). Many also die in early "accidents" while acquiring the flight-skills they'll need to survive. It's a rough world.
If it's an adult, you may not succeed in getting it to eat quick enough to nurse it back to health. If it's a youngster, you may... If you can get it to eat, worms, crickets, flies, mealworms, waxworms, maggots, etc, will all work. How much? Whatever it will eat... They can eat 20% of their body-weight per day... You won't be able to over-feed it, because it'll just stop eating... If that works, it's best chance of survival is going to be being released ASAP, if not sooner. Give it a good meal, and let it go (in the morning). If it isn't allowed to fly at this very stage, it won't continue to develop properly, and will be doomed regardless of how healthy and flighted it appears later. Keeping it 3-4 days is too much.
At this stage of the game, the other aerial predators also have young that are right now learning to hunt by hunting these recently-fledged birds. A few days head-start for it's competitors (while they're learning, and the guy you have in a box is not) will mean death to the lil' fella. That's how it works...
It's a federal crime for you to have that lil' guy, or any feathers, etc, for that matter, although it's not likely to be enforced.
