I have two adolescent roosters vying for alpha status. They often have crowing contests, but yesterday I heard a different sound. Two pullets were tussling, and as they chased each other around, the two roosters started calling Buk-buk-buk-ACK repeatedly. What does this mean? I've heard this call several times before, but this was the first time I heard the two competing roosters use it as they called back and forth.