Binki
Songster
Your setup description sounds ideal! I love it, different textures, levels, breaking lines of sight and creating extra places like keeping things a few inches from the wall so they can run behind it 
It really helps to keep them busy and content, I used the same principle in my aquariums and was able to keep puffer fish and betta (Siamese fighting fish) together plus a whole bunch of other species with no damage because it was all natural, wood, stone, various plants, cover, places to investigate and hide, foraging for food, etc.
I find that when there is animal "aggression" in fish or quail (and other animals), it's more "I'm the boss! Get out of here!" than "I'm gonna kill you!!" and so when they're being charged at, if they have a place to run away to/hide, then they're truly submitting and the problem goes away once the dominant bird can establish that by seeing them disappear out of sight.
When it's just an open cage or aquarium and the animal has nowhere to hide, the aggressor can perceive this as not submitting and that's when the damage occurs.
Regarding the shelves, mine love different levels and it creates a space underneath
you can do a ramp or they can jump up and down hehe - particularly good for when a female wants to get away from a male - he hasn't figured it out but all the girls have! 

It really helps to keep them busy and content, I used the same principle in my aquariums and was able to keep puffer fish and betta (Siamese fighting fish) together plus a whole bunch of other species with no damage because it was all natural, wood, stone, various plants, cover, places to investigate and hide, foraging for food, etc.
I find that when there is animal "aggression" in fish or quail (and other animals), it's more "I'm the boss! Get out of here!" than "I'm gonna kill you!!" and so when they're being charged at, if they have a place to run away to/hide, then they're truly submitting and the problem goes away once the dominant bird can establish that by seeing them disappear out of sight.
When it's just an open cage or aquarium and the animal has nowhere to hide, the aggressor can perceive this as not submitting and that's when the damage occurs.
Regarding the shelves, mine love different levels and it creates a space underneath

