A:
according to "The deer Dr." from field & stream.... A short bleat is the estrus call from a doe. If you let the bleat go long for the full drop of the can it actually is an alarm bleat to other deer.
Hence... driving them away. Not sure if this is true... but the method of a quick short bleat , about half the drop of the can.. worked for me, actually turning the buck around as it walked away ,and brought him right back to me.