mixing 11 week old chicks with established flock

[lcronkr]

My flock has a huge outdoor "Pasture" (It is 60 by 40 feet long) with many places to hide.
While the big girls are outside in the run all day, the chicks come out from the corner, but still don't dare go outside where the hens are.

 

[lcronkr]

We have decided to build a separate pen for a few more weeks and git rid of half of the big flock and then we will try again. Thanks for help!