I don't know if I found this here, it has been here before, but I think it is a great video to help with cadence and varying your calling to sound like a hen.
http://www.youtube.com/watch?v=KGTwoWu1D2s
Nice hen talk but would have been a lot better if the cameraman would have left the controls alone! In, out, in , out, to the right, to the left, up, down...:angry9: