Yes ferrets are more or less domesticated polecats although they are sometimes not that domesticated LOL Not many kites here, loads of Buzzards, Sparrowhawks, a few Goshawks and quite a few pairs of peregrines, they are amazing birds to see.
Sometimes motors can give off a whine or whistle when doing nothing, I think it may depend on the drives. I know mine whistled constantly with the drives I had at first but they dont with the geckos. Have you tried messing with the accel and velocity on the motor tuning pages?
Hood