The grumbling sound is pouting that she has to be caged for the night, just like a youngster complaining its time for bed...LOL
Actually, your questions would fair better with Susan, I have never became very close to any Pigeons the way I have while handfeeding them for adoption.
Most of my rescues are either Feral or Racers, none are hand tamed as the ones I have adopted out, and I ship them out as babies, so the adoptors see and endure different things that I don't deal with...
Susan trained Gem to free fly by placing him down on a fence then backing up, she mentioned Gem would fly to her at 5 feet then 10 feet, but I believe she started with placing Gem on her shoulder and just sitting outside on a chair to allow Gem to learn his surroundings, and as Gem became more gutsy he would fly further away each time, I remember the day Gem flew up on the roof, Susan was very scared, she posted this picture...
Now I will tell you the same thing...Heather...Mia will never leave you...not intentionally, She will always be loyal to you and always return to you...always....
You have 2 major concerns...Preditors, Sweethearts...
Basically the same worries with your human children.
Sooooo, place Mia on your shoulder and go sit on your front steps for awhile, allow your bird to learn her surroundings....take things slow...for both of you...
When I free fly my birds, none are hand tamed...they come and go as they please....
Best you get together with Susan concerning this issue as both your birds are hand Tamed.
Kate doesn't free fly.
Camilles situation is unique also, Mira free flies along side of her other Pigeon Mollie, Camille lives in town and Mira lives on the farm with Camilles father, but when Camille goes to the farm to visit, Mira is as loyal as can be to her...
Sooooo, touch base with Susan, and or look over Susans threads here in the forum and see what she has posted, the same with Camille and Mira...
Mia will never leave you Heather....never.....
Arty