chukars are nearly impossible to differentiate gender and ringnecks take about 3ish months before can definitively determine gender (exception being melanistic mutants) while quail mature and can be sexed at 3-8 weeks. As far as integrating, you can put the chicks in with quail as soon as they no longer need accessory heat. my aviary is approximately 700 sq ft with several hiding places. while quail only require 1sq ft per bird, the chukar and pheasant will require more space as adults. other issue to consider with your set-up is that pheasant and chukar can be very flighty and if they escape, it is rare that they can be retrieved. you don’t list your location....does your state require a permit for the birds you are planning to get?
