If you shoot a Mandarin in N. America you are shooting someones escaped pet. Nothing wrong with that - they are beautiful birds!
Correction. If you shoot one in the US you are shooting the offspring of someone's pet.
Private reserves have been releasing them for years for "executive" hunters. Enough have gotten away that they have started to establish themselves.
I hunted at one with a gun manufacturer in Minnesota a few years ago. They turned loose about 100 that day. Most were shot but several flew away. The manager said they lose several just about every time they have a shoot.