Hi all. I have four new chicks. They're about 6 weeks old. Two of them hop up on the roosts and hang out there, but two don't even attempt it. My last round of chicks were all on the roosts from about a month old on. Do you think these two will get around to it? Or are they just ground chickens? I'm hoping they learn to sleep on roosts before I put them in with the Big Girls. Any ideas? Thanks in advance.