Hi----We are raising chickens and they are now to the point of wanting to roost. However, when we go out to the coop, all the chickens are up on the roosts except our Silky and our Frizzle. My kids have pointed out that neither one of these chickens fly much at all. We have roosts of varying heights but they still don't seem to go up there. We always find those two chickens huddled together on the floor of the coop. Is this something I should worry about? Thanks!