Chicks learned they could Fly to get Out!!!!

We were working on the chicks sleeping quarter this morining.. We got the outside nesting box finished and were puting the roost together and screwing it in.. I went past where where we have the chicks for the day ( old doors and hardware cloth fixed up for them to run in during the day..

I look down and all three of them are runing around on the wrong side.. I check for a space don't see any.. catch them and put the back in.. I hadn't even turned my back and on flew to the top of the door and sat there.. LOL.. Will keep them in their coop since it's all finished except for the finishing touches.. Bring them in at night for couple more weeks.. they are weeks old today...

When I can I offer them grit.. they were finding a little bit of bugs while in the grassy enclosed area.. plus I let them roam a little in the evening.. supervised.. they ate a slice of tomato yesterday.. and gobbled down 4 stink bugs I found. have discovered worms are good.. LOL.. and devour meal worms now..
what other treats are the old enough for.. I have them on chick starter/grower. purina