I've had luck with it with two smaller bucks and a herd of cows. I called two bucks 300 yards across the field directly to my stand. Both were young bucks. I've also had about 30 head of cattle come to my stand mooing their asses off and searching for this imaginary baby cow. In Field and Stream this past month, a whitetail 'expert' said in his 30 plus years of hunting he has never heard an estrous bleat. What he believes is the reason this call can be successful is because a buck is mistaking the estrous bleat for a fawn bleat. The buck might believe that if the fawn is bleating then the mother might be around too.