Guilty questions and satisfying answers
Guilty questions of this nature plagued me as I drove back home from POS today, somehow noticing more Keskidees than usual along my route.
So ... I just looked up 'what to feed a baby bird' (for future reference) and came across the below extract. It makes me feel better about the decision I made in the end.
If the bird is uninjured you should ask yourself, "Is it really an orphan?" Nine times out of ten the answer is no! Look for nests in nearby trees and shrubs. They are usually well hidden and hard to get to. If you can find the nest, simply put the bird back in it. It's a myth that the parents will not care for young birds that have been touched by humans. In fact, birds have a poor sense of smell. Great horned owls kill and eat skunks without even noticing their overpowering stench.
If you can't find the nest, put the baby bird in a shrub or tree - somewhere up off the ground. You can even provide a substitute nest by tying a berry basket (with drainage) up in a tree. Most often this is all the help a baby bird needs. As soon as you leave, the parents, who were probably watching you the whole time, will return and continue to feed the fledgling. If you want to be sure the parents are still around, observe the baby bird from a distance, preferably with binoculars. If the parents don't return to an undisturbed nestling in two hours, something may be wrong. The parents may have been killed by predators or hit by a car. Don't worry if you only see one parent. A single parent can raise the young alone.
This site (where the above extract is from) has info on what and how to feed baby birds.