Moose are one of a number of species where males fight for the right to mate with their preferred female. As such, you might think female moose don't have much say in the matter. That's where you'd be wrong.
Moose societies are polygynous, which means that males mate with lots of different females but females only have one partner. This means that a big, aggressive male has an excellent chance of securing lots of partners, whereas a smaller male runs the risk of being shut out entirely. The autumn rut is when the reproductive pairings are sorted out, and often that involves a whole lot of fierce fighting between males.
So what role do females play in all this? Well, until now, all we really knew was that they would sometimes let out what's known as "protest moans" when a male approached them. These moans would bring other males, which would then often lead to a full-on moose battle. Researchers hadn't really paid attention to the protest moans, assuming courtship was really being determined in the fights.
But Idaho State researcher Terry Bowyer says it's more complicated than that. As it turns out, the females are using some pretty crafty strategy when it comes to their protest moans:
"Female moose gave protest moans more often in response to courtship by small males, even though the large males engaged in more courtship. This behaviour by females helped them avoid harassment by smaller males, but also provoked fights between large males. Male aggression was more common when females gave protest moans than when they did not, indicating that this vocalisation incited male-male aggression."
So, with a few well-chosen moans, the female moose can make the males fight for their love. Dr. Bowyer explains:
"Protest moans allow females to exert some choice in a mating system where males restrict [that] choice through male-male combat. We believe that female choice is a more critical component of mating systems in polygynous mammals than previously thought."