Two of my robins died (I don't think I introduced fruits soon enough.. after a certain point, robins need fruit.. they aren't meant to eat bugs all the time) and I released one.
The first one I had (Rest in peace, Badger) became far too attatched to me to release, even though we tried very hard not to let that happen. I kept her until she passed away. I will dig up pictures of her.
I require pictures of your son.