I use patio netting and a retractable clothesline to keep mine apart. But Miss Jewel scales that net like it's nothing. Which is okay and necessary because she has two boyfriends. And Zephyr sneaks under the bottom sometimes. But usually they tell on each other. If one of the boys sees another boy getting ready to be naughty, a bunch of head fluffing and angry garbles start going. They entire flock will start this angry chattering. Or maybe they're saying..."fight, fight, fight!"... They know where they are not supposed to go. I will be changing most of it to solid wood and stainless mesh panels.
And on Happy and Chya's end, I put a net up just to keep others from getting spooked and flying into their area. Chya can fly around the net to get to me.
Honestly, do not trust littles around bigs ever...if he escaped his cage when you weren't home, he (if like mine) would go straight to the big birds cage. I have missed closing a door in the past and had bloody toes when I got home.
