NEVER!!! why?:
#1. disease! Coryza is the most common disease transferred from chickens, ducks or turkeys to game birds. The chicken may never exhibit any illness, but can
easily pass it on to your quail. Unfortunately, as the quail have little-no immunity to this, it'll spread like wildfire killing most if not all of your flock (defiantly your pair). It passes usually through the droppings so always make sure to handle your game birds before your chickens.
#2 Pecking. Your chickens can peck at your quail and give them nasty wounds, possibly leading to infections.
Some people have gotten away with this, but they eventually get the disease and that's just a risk that many are not going to take.
Edited to add: Not that this affects the relative question but, what type of quail is this pair (button, coturnix, bob white, valley, blue scale, mountain,gambel)? cause if it's coturnix or bob white (usually most common) then you really should have 4 females to 1 male to avoid injuries, please correct me if I'm wrong
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