To understand elk behaviour during the secondary breeding cycle, you have to consider what’s already happened. During the pre-rut, bulls bugle to attract cows and build their harems. Then during the peak rut, they only think about two things: mating and fighting. That means they’re bugling to either to round up cows or challenge other bulls.
Herd bulls focus on breeding as many cows as possible while keeping other bulls away. Meanwhile, satellite bulls—those mature sub-dominant elk lurking near a herd—try to steal away as many cows as they can, without getting whipped in the process. This month of gathering, chasing, fighting and breeding takes a harsh toll on elk, so once it’s over, they’ll rest up until the secondary breeding beings.
By the second estrus, herd bulls are too worn out to fight, but they’re still thinking about cows. But the satellite bulls, which didn’t have to defend a harem, have more energy. Combined with a month of elevated testosterone, that gives them a little more courage to go after cows, and the result can be fairly chaotic.
Think of it this way: During the peak rut, the bulls are like senior elementary school students picking two teams to play at recess; everyone knows who the best players are and who they want on their team, so the picks are straightforward. During the secondary breeding, on the other hand, elk resemble a kindergarten class trying to line up for the first time—nobody has a clue where to go, and they can’t make up their minds. It’s a free-for-all process with no predictable outcome.
As a result, the amount of bugling can be mind blowing during secondary breeding, with mature bulls constantly sounding off at the slightest hint of a cow in heat. With the large harems mostly broken up, even the younger two- and three-year-old bulls bugle frequently as they find small groups of cows entering estrus. Bugles at this time are associated with bulls following cows that are nearing estrus, but are not quite there yet, as well as bulls trying to attract cows.