Roughly 400 Sq Ft, In Community Housing Like That I Recommend At Least 2 Sq Ft Per Bird For Bobs As A Minimum (bobs Now, Not Coturnix-- Big Difference) So Roughly 200 Birds. But If You Push Maximum Density Like That You'll Need To Definately Thin Them Down As Soon As Possible Upon Maturing. They're Mean Lil Suckers And Will Beat The Snot Out Of Each Other Quite Visciously In A Contained Environment Like This. So As Soon As They Get To Be Teenagers, Say 18 Wks Of Age Or So You Will Likely Start To Experience Agression Problems (if Not Sooner) So Keep A Close Eye On Them As They Grow, Or Get Good At Using No Peck Bits. Also Plan Your Pen Accordingly... These Guys Are Like Taco Bell To Predators And The Predators Will Come From Miles Around To Get Them, So Make The Pen Quite Bomb Proof.