Watch Nature Season 26 Episode 9 Online

In the animal world females often call the shots. But their decisions may be surprising. In an effort to understand the mating game, NATURE follows biologist Chadden Hunter, PhD, through the Simien Mountains of northern Ethiopia, as he observes a troop of geladas, close cousins of baboons. He found that in gelada society females make all the decisions about mating, even though males are twice their size. The males are evaluated on everything from body heat to baby sitting skills. And once selected, no male gelada can ever rest on his laurels. Another male is always auditioning for his job. You’ll also see female barn swallows that choose a male by the color of his chest and encounter a robotic sage grouse that is helping researchers learn about this species’ elaborate courtship displays.