Mixing chicks, size or age?

[southernsibe]

When it comes to mixing chicks, is it more important to pay attention to size or age? I have 7week old bantem cochins, and 3 week old cuckoo marans. These guys are nearly all the same size, in fact, some of the cochins are smaller then the marans. Can they safely be put together? Is it behaviors with age, or size?

Thanks
Rachel

 

[Chick_in_Indiana]

I have always gone by size and had no problems.