Perhaps this is a silly question ... but isn't it rather obvious that the baby bird inside the egg will be the exact same species of bird as the mother bird sitting on the egg?? Did I miss something? If the mother is a robin, the baby will be a robin, and so on and so forth. So instead of describing the egg, why not describe the mother bird?

As far as attempting to hatch the egg or a wild bird and raise the baby yourself, honestly, it is HIGHLY unlikely to happen. Every species has different requirements, and unless you are or happen to know an expert in the field of hand-raising hatchling starlings, blue jays, whatever ... you have no way to know what they are. In addition, possessing almost any wild bird without a lisense is illegal. You must be a lisensed wildlife rehabilitator to have them in your possession.

I've attempted to raise dozens upon dozens of baby birds while affiliated with the humane society here. I managed to raise to adulthood exactly two house sparrows, one grackle, two starlings and two pigeons. So seven success stories out of probably fifty attempts over the course of a decade. Not good odds ... and I did a LOT of research.

I understand your desire to help. We are all here because we love and want to help animals. But it IS probably best to just leave the situation alone and let nature run it's course, harsh as it seems.