The smaller bull does the pop n grunt as a last ditch effort to hook a cow. kind of like me after I get busted and they quit listening to all other calls, I stop them with a pop and grunt. The big bull screams at the satellite just like he did before whipping his first competitor. He seems slow in the water against the current heading up river towards his harem. Like an old guy that doesn't move very fast but when he gets to you hes gonna whip ya. The cows know who daddy is and go running when that beta bull shows up. No need for the big bull to say nothing to the cows.