I built a perch inside their coop. Our new BB Red rooster, Black Cochin Bantams, and our Baby (sort of baby) Aracaunas. I've seen them all get up their (besides one of the Aracaunas and one of the Black Cochin Bantams (the rooster out of the Black Cochin doesn't even get up there?....)). But not one of the two White Silky Bantams has gotten up on the perch. Why is this?