The 3 older chicks are 5.5 weeks and mostly fully feathered. I have a tiny 4 and 2 week old with only wing and tail feathers. I put the older 3 in a extra large plastic dog crate and kept the little ones in the extra large wire dog crate. The 5 week olds are getting too warm with the wire crate 1/2 covered for the two younger ones. It didn't work. Poor Maple, the 4 week old freaked out! I never heard a little bird in such distress being separated. So, back they went. I put the heat lamp as far in the corner as possible and only covered the corner of the wire crate. The 3 older ones don't care where they go, but little Maple is much happier. Hubby okay'd for me to buy one more chick, so I'm going to pick the new one up Friday when the shipment gets in. I'm looking to add a Millr Fleur D'Uccle to the flock. Or maybe a frizzle. I heard d'Uccles are very sweet friendly birds though. Maybe I will try and move the 4 and keep the 2 smallest together. Hopefully the coop will be finished this weekend. It would be nice to move the 4 oldest ones out there instead of the dog crate. If it wasn't for the chicken math, they would all be the same age.