my 4 week old pullets don't seem to know how to go up and down any type of ramp. I have one that comes out of their baby coop, but also a ramp in the chicken tractor (I've only put them in this a couple of times for 1/2 hr at a time) they just sit at the top. once in a while they will "fly" down, but don't seem to know how to get down. I've tried sprinkling their food down the ramp, but nothing helps. Is this a learned behavior that they will figure out once they get older?