If you touch a baby bird will its mother reject it?

No, children are usually told that by parents, so they don't touch the bird, then causing the bird to become hurt, or be taken home by the child. That is the one thing you shouldn't do with a baby bird, take it home. The bird needs its mother to survive. If the mother of the bird notices that an egg is moved, then it may abandon the nest, but that behavior is very rare. That would because of sight, and not smell. So even though they probably wouldn't abandon their young be sure not to handle an egg of a bird, or a baby bird. - John Baskin